THE FRACTURE CONTROLLED MINERALOGY WITHIN THE OXIDE ZONE OF
THE FLORENCE PORPHYRY COPPER DEPOSIT, PINAL COUNTY, ARIZONA
by
John R. Davis
A Thesis Submitted to the Faculty of the
DEPARTMENT OF GEOSCIENCES
In Partial Fulfillment of the Requirements
For the Degree of
MASTER OF SCIENCES
In the Graduate College
THE UNIVERSITY OF ARIZONA
1997
2
STATEMENT BY AUTHOR
This thesis has been submitted in partial fulfillment of requirements for an
advanced degree at The University of Arizona and is deposited in the University Library to
be made available to borrowers under rules of the Library.
Brief quotations from this thesis are allowable without special permission, provided
that accurate acknowledgment of source is made. Requests for permission for extended
quotation from or reproduction of this manuscript in whole or in part may be granted by
the head of the major department or the Dean of the Graduate College when in his or her
judgment the proposed use of the material is in the interests of scholarship. In all other
instances, however, permission must be obtained from t1vthor.~
SIGNED:
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APPROV AL BY THESIS DIRECTOR
This thesis has been approved on the date shown below:
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Professor of Geosciences
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ACKNOWLEDGEMENTS
The financial support for this project was graciously provided by the Growth and
Technology group of BHP Copper Inc. I would like to thank the Florence Project Senior
Geologists Jacqueline Seguin and Corolla (Cori) Hoag for their many suggestions,
assistance, and endless flexibility with my internship scheduling. This work could not
have been completed without the aid of the entire Florence Project staff, in particular, Jeff
Shaw and Michael Brewer who provided me with numerous reference materials and vital
critiques during the step-by-step progression of this project.
My deepest appreciation goes out to Dr. Spencer R. Titley and BHP Senior
Geologist Richard K. Preece for their faith in my ability to undertake and complete this
study. I thank you both for the numerous discussions and suggestions during the course
ofthis project.
I would like to give a special thanks to Jennifer Brick and Jonathan Rudders for
always standing by me, friends like you are a rare find.
Finally, I would like to express my gratitude to my undergraduate mentor, Dr.
Kevin C. Cole; thank you for always having faith in me and for giving me the push to go
further.
4
TABLE OF CONTENTS
LIST OF FIGURES ........................ .. ..................................................................... ........ .... 7
LIST OF TABLES ............................................................................................................. 9
ABSTRACT ...................................................................................................................... 10
INTRODUCTION .............. ... ................................................ ................................. .......... 12
PROPERTY HISTORY .................... ......... ... .. ... ............ ...................... .... ...... ....... ... 12
ORE DEPOSIT GEOLOGy ........................................................................................... 15
STRUCTURE ........................................................................................................... 18
ALTERATION ......................................................................................................... 19
MINERALIZATION ................................................................................................ 20
IN SITU MINING .......................................................................................................... .. 22
SCOPE OF RESEARCH .......................................... ............ ......................... .. ......... ...... 25
RELATED WORK .................... ......................................................................... ...... 25
SAMPLE COLLECTION ....................................................................................... .25
FRACTURE DATA ......................................................................................................... 29
METHODS OF STUDY .......................... .. ....... ............................................................ ... 32
VISUAL INSPECTION .. ......... ..................... ..................... ...................................... 32
X-RAY POWDER DIFFRACTION ..................... .... ........... .......... .... .... ........ ...... .... 36
Sample Preparation ........ ... ... .. ...................... .................... ............................... 36
Identification Procedure ............................... ...... .. ... .. ............ .. ..... .... .... ... ........ 37
5
TABLE OF CONTENTS - Continued
RESULTS - XRD .... .... ... ... ............. ................ ..... .... ... ... .......... ...................... ..... .... ..41
Distribution By Mineralogy ........... .... ... .... ..... ......... .. ..... .... .... .... ... .. .. .... ... .. .. ...45
SCANNING ELECTRON MICROSCOPY ... .... ...... ..... ....... ... .......... ................ ... ...48
Sample Selection ............................................................................................ 49
Sample Preparation - Unleached ...... ...... ... ... ..... ..... ... ...... ........... .................... .49
Sample Preparation - Leached ... ............ ................................. .. ..... ......... ........ 50
RESULTS - SEM ........... ... ...... ... .. .... .. ..... ... ..... ......... ...................................... ........ ..51
Image Recognition And Identification ................ ...... ..................................... 51
EDS - Unleached Results .................................................. ................. ............. 57
EDS - Leached Results ..... ...... .. ..... .................. ..... .. ... ...... ............. ... ..... ....... ...62
Leach Solution ...... ... ... ..... ............... ....... ............. ................................... 67
ASSAY DATA ........................ .... .... .. ... .. ..... ......... ...................... .. .... ..... .... .................. .... .. 69
MINERALOGY DISCUSSION ...... ... ... .... ....... ........ .............. ......................................... 71
MONTMORILLONITE ............................................................ ... .... ....... ....... ... ..... .. 71
HALLOYSITE .. .... .... .. .. ... .. ...... ......... ....... .. .... .. ..... ... ... ... .... ..... ........... .... ........... ....... 72
KAOLINITE ............. ..... ... .... ................................................................................... 72
ILLITE GROUP .......... ..... ...... .......... ... .... ..... ... ................ ......................................... 73
SEPIOLITE ... .. ...... ......... ... ... ..... ........... .. ...... ..... .... ... ... ... ............ ....... ... ... .......... ...... .73
CHRYSOCOLLA AND NEOTOCITE ............... ........ .......... ........ ..... .......... .... .. .... .73
6
TABLE OF CONTENTS - Continued
GOETHITE, HEMATITE, AND JAROSITE ................... .............. ... ............. ......... 74
GYPSUM, CALCITE, ANHYDRITE, AND CHLORITE GROUP .. ............. .. ...... 75
CONCLUSIONS .................. ............... ..... ..... ....... .... .......... .... .......... ...... .......................... 76
APPENDIX A ................................................................ ....... .. ........................................ 78
APPENDIX B ...... ................. .. ...... ...... ..... ....... ............................ ........ ........ ........... .... .... .84
REFERENCES .......................... .................................................................. .. ...................87
7
LIST OF FIGURES
FIGURE 1.
State map of Arizona showing the location of the Florence Deposit.. ... .... 14
FIGURE 2.
Generalized geologic cross-section through the Florence ore body ... ....... 17
FIGURE 3.
Schematic cross-section of an in situ mining system ...................... ........... 24
FIGURE 4.
Diagrammatic representation of the fifty-foot sample site spacing .. ......... 28
FIGURE 5.
Fracture densities plotted versus drill hole depth for each of the three
core holes sampled ....... ......... ..... ............................................. .............. ..... 30
FIGURE 6.
The number of occurrences for each of the general groups as noted
during sample collection .... ....... .............. ......... ................... ...... ..... .... ... .... .34
FIGURE 7.
Schematic representation of the observations made while collecting
samples as a function of drill hole depth ... ..... ........ ... .... .. ..... ..................... 35
FIGURE 8.
Schematic representation of all the phases identified by xrd for all
the mineralized fractures as a function of drill hole depth ........ ....... .... ..... .44
FIGURE 9.
Generalized cross-section showing the distribution of the dominant
fracture controlled phases ... .. ................................ ....... .. .......................... ..4 7
FIGURE 10.
SEM images of montmorillonite ...... ... ............ ......... ....... ........ ............ ....... 53
FIGURE 11.
SEM images of illite-montmorillonite transition and kaolinite ......... ... ..... 54
FIGURE 12.
SEM image of typical chrysocolla sample .. ... ..... ... .... .................. ........ .... ..55
FIGURE 13.
SEM images of chrysocolla .............. .... ........................ .. ..... .... .... ... ........... 56
FIGURE 14.
Ternary plot of the EDS data gathered on all unleached samples ... ........... 61
FIGURE 15.
SEM images of montmorillonite after leaching with pH = 1.51
raffinate ................................................ .... ........... .......... .... .... ... ... ............... 63
FIGURE 16.
SEM images ofchrysocolla and kaolinite after leaching with
pH = 1.51 raffinate ........... ................ ........ ......... .... .. .......................... ......... 64
8
LIST OF FIGURES - Continued
FIGURE 17.
Ternary plot of the EDS data gathered prior to and during leaching
experiments ................................................... .. ............... ..... .... .. ................. 66
FIGURE 18.
The molarity of the major dissolved components and the pH for
the initial and final raffinate leach solutions .... ............. .... ............. ............ 68
9
LIST OF TABLES
TABLE 1.
Average fracture densities for each drill hole ...... ........... .. .................. ....... 29
TABLE 2.
Diffractometer settings and constants used for all x-ray runs .. ............. .....36
TABLE 3.
The d-spacing window used to compare measured peaks with
published peaks ... ..... ......................... ....................... ... .. ... ..... ............... ... ... 39
TABLE 4.
Level of confidence in determining whether a mineral phase
was present ..... ... ..... ... ................................... ............. ....... .. .. ...................... 40
TABLE 5.
Minerals found as fracture coatings and level of confidence .... .... ... .... ..... .41
TABLE 6.
Decreasing order of abundance for the ten clay minerals identified
by xrd .......... ............. .. ................................................................................ 45
TABLE 7.
Machine specifications for the FESEM and EDX Microanalyzer .......... ...48
TABLE 8.
Mineral phases identified using SEM .... ... ....... .......... ..... ......... ... ............... 51
TABLE 9.
Elemental analyses of all unleached samples ... ..... ........................... ........ .58
TABLE 10.
Elemental analyses of all leached samples ............ ..... .... .. ..... ... .. ............... 65
TABLE 11.
The acid soluble copper assay percentage corresponding to intervals
of dominant clay-type mineralization ...................... ... .......................... ..... 70
10
ABSTRACT
A systematic sampling program was conducted on the Florence porphyry copper
system to determine the fracture controlled mineralogy within the oxide zone of the ore
body. The Florence ore body is owned by BHP Copper Inc., and will be mined using in
situ mining techniques. Understanding the fracture controlled mineralogy is critical to
predicting the effects of leaching during the mine development process.
The deposit is buried under 100 meters of Tertiary and Quaternary sediments.
The Oracle granite is the host rock to the causative Laramide age granodiorite porphyry
intrusions. Oxidation ofthe deposit occurred post-tilting and pre-faulting. The central
portion of mineralization is bound by two NW-trending normal faults.
Forty-five samples were taken from a cross-section through three diamond drill
holes. Each hole was sampled throughout the oxide zone every fifty feet with a subinterval of two feet. Both X-ray Powder Diffraction (XRD) and Scanning Electron
Microscopy (SEM) were employed in this study to aid in the identification process and to
determine the distribution of the fracture controlled mineralization and copper-bearing
phases. Of the 19 secondary mineral phases identified using XRD, 82% of all
mineralization came from the following phases: Montmorillonite (29% with the 15 A
variety accounting for 13%), goethite and hematite (29%), halloysite (9%), kaolinite
(9%), and chrysocolla + 'Cu-wad' (6%). The remaining 18% of phases identified were
other montmorillonite members (i.e. at various hydration states or transitional phases),
•
1" ,
11
minerals. As many as five different mineral phases were identified over a single two foot
sample interval. Nine of the nineteen phases were confirmed using SEM. Samples were
identified visually based on morphology and chemically by energy-dispersive x-ray
spectrometry (EDS) data. The SEM data were used to confirm XRD identification and to
determine the location of the copper with respect to the clay phases. EDS analyses were
also done on selected samples that were leached with sulfuric acid to simulate the in situ
process. Results indicate that chrysocolla readily gives up copper in a low pH
environment. The SEM images and data show that, 1) Morphologically, there are no
intergrowths of chrysocolla within the clays; and 2) The copper in the clays resides within
the octahedral site.
The fracture controlled mineralogy of the Florence ore body shows no spatial
variability within the cross-section studied and there is a uniform distribution of clays,
chrysocolla, and iron-oxides. The fracture mineralization is dominated by iron-oxides
(goethite ± hematite). The abundance of all fracture mineralization decreases with depth.
Copper is distributed ubiquitously in the clays, in particular with 15 A montmorillonite.
12
INTRODUCTION
The field area for this project is the Florence (Poston Butte) porphyry copper
deposit. The property is located in Pinal County, 2.5 miles northwest of Florence,
Arizona (Figure 1) and is owned and operated by BHP Copper, Inc. The Florence ore
body is in the Southwestern North America porphyry copper province that has been the
focus of several theses, dissertations and publications spanning the past few decades. The
interested reader is referred to the volumes edited by Titley and Hicks (1966), Titley
(1982), and Pierce and Bolm (1995) for collations of papers on the porphyry systems of
Southwestern North America; also recommended are the papers by Titley and Beane
(1981) and Beane and Titley (1981) for detailed information on the characteristics of
porphyry copper systems. Florence, together with the Silver Bell, Santa Cruz, Sacaton,
and Lakeshore deposits, all part of the Basin and Range Province, form the western flank
ofthe southwestern porphyry copper province (Cook, 1994).
PROPERTY HISTORY
Since discovery of the Florence porphyry deposit in 1969 by Conoco geologists, a
vast amount of data has been collected on the property. From 1970 to 1975, Conoco
drilled 659 rotary drill holes and 396 diamond drill holes, as well as developed a single
level, underground, pilot mine resulting in over a mile of drifts and cross-cuts (Nason et
aI. , 1982). Conoco decided in 1975 not to develop the deposit presumably due to low
copper prices and the relatively large capital investment needed (Magma, 1994). The
13
property sat dormant until 1992 when it was acquired by Magma Copper Company.
Magma began a pre-feasibility study in 1993 on the Florence deposit to determine the
most efficient method of mining the ore body (Hoag, 1996). This progressed into a
feasibility study which began under Magma in 1995 and continues to the present under
the new property owner, BHP Copper, Inc.
14
-
--- - ---- - -- - --_.,
~
FLORENCE DEPOSIT
•
Phoenix
•
Tucson
100 km
Figure 1. State map of Arizona showing the location of the Florence Deposit.
15
ORE DEPOSIT GEOLOGY
The geology of the Florence deposit has been described by Anderson et al. (1971),
Conoco (1973), Nason et al. (1982), and summarized by Hoag (1996). Therefore, the
geology will only be summarized here in order to provide some background information
on the area. The lithologic unit descriptions, as well as the alteration and mineralization
assemblages described are based on this author's observations while logging
approximately 5,000 feet of drill core. See Figure 2 for a geologic cross-section of the
deposit.
The dominant lithologic unit is a Precambrian quartz monzonite (correlative with
the Oracle Granite). This unit is known to have intruded the Precambrian Pinal Schist as
evidenced from drill core data. The monzonite is felsic and phaneritic, but may appear
porphyritic locally. Large (1-2 cm) subhedral, perthitic orthoclase feldspar phenocrysts
are set in a hypidiomorphic to xenomorphic matrix of quartz with lesser amounts of
biotite lenses, plagioclase feldspar laths, and trace amounts of magnetite, sphene, apatite,
and rutile. The monzonite has been intruded by a series of Precambrian diabase dikes.
These dikes range in thickness from a few centimeters to several meters. In general, they
have a dark grey to black aphanitic matrix with localized small (1-2 mm) plagioclase
feldspar laths yielding a faint ophitic texture.
A series of Laramide intrusions are also known to cross cut the Precambrian
quartz monzonite and diabase dikes. The Laramide is dominantly represented by several
phases of granodiorite porphyry (62 ± 1 m.y.) and, to a lesser extent, younger (55-60
16
m.y.) Tertiary andesite and quartz latite dikes (age data from Conoco as reported in
Nason et ai., 1982). The granodiorite porphyry's aphanitic matrix ranges in color from
light to dark grey, indicating a variable mafic content. The porphyritic texture is shown
by small (2-3 mm) phenocrysts ofeuhedral to subhedral plagioclase feldspar, 1-3 mm
biotite lenses, and less common 2-4 mm quartz eyes. The andesite's aphanitic matrix is
generally various shades of medium grey and locally contains small plagioclase feldspar
laths and remnant zeolite-filled vugs. In local cases, mafic minerals show flow banding.
Overlying the bedrock units are Tertiary and Quaternary age basin-fill sediments
approximately 100 meters thick. The basin-fill is characterized by unconsolidated,
moderately sized gravel, sand, silt, and clay lenses.
17
CROSS SECTION LOOKING NORTHWEST
LEGEND
D
, .,
_~::_>
II
D
D
Overburden
Tertiary Andesite
Tertiary Granodiorite Porphyry
Precambrian Diabase
Precambrian Quartz Monzonite
", Faults
Figure 2. Generalized geologic cross-section through the Florence ore body. The section
is oriented N300E looking northwest. The thin vertical black lines represent diamond
drill holes used by the author to construct the section. The three labeled holes in the
center are those from which the samples for this project were collected. The geology is
described in the text. No vertical exaggeration.
18
STRUCTURE
The structures in the Florence deposit have been interpreted from extensive drill
core data and mapping that was done on the underground workings. Drill core
observations have been supported by data from an Acoustic Borehole Televiewer
(BHTV); an oriented geophysical tool that digitally records changes in competency (i.e.
fractures and faults). The deposit is within a complex, northward trending horst block
resulting from Basin and Range faulting. Two main features associated with this event
are the Party Line and Sidewinder faults. The Party Line fault strikes N35°W and dips
45-55°SW and bounds the eastern edge of the mineable portion of the ore body. The
Sidewinder fault has a similar strike and dip orientation (NO-lOoW, 45-55°SW) and
bounds the western edge of the mineable deposit. The Sidewinder fault is also the
footwall to a zone of en echelon, normal, north-striking faults that dip 45°W and
vertically displace the deposit as much as 400 meters. The proposed Ray Lineament,
striking N700E and dipping steeply either NW or SE, runs through the Florence Deposit
(Anderson et aI., 1971). This older structure has been offset by the younger Basin and
Range faulting. Wilkins and Heidrick (1995) place the Florence deposit among those
which have undergone Tertiary rotation in excess of 80°; however, detailed structural
interpretation at the mine sight has failed to present evidence supporting this idea. The
drill core data suggest that if rotation occurred, it is probably less than 30°. In addition to
the permeability created by the tectonic activity, the Precambrian quartz monzonite has
been intensely fractured due to numerous intrusions and the influx of hydrothermal
19
fluids; thus adding to the permeability necessary to mine the ore body using in situ leach
techniques.
ALTERATION
The primary hydrothermal alteration of the oxide zone is characterized by
hypogene orthoclase-biotite (potassic), quartz flooding, and to a lesser extent quartzsericite (phyllic), alteration assemblages. Secondary orthoclase generally exhibits
different alteration styles for the two major rock types. In the Precambrian quartz
monzonite, secondary orthoclase replaces primary orthoclase and is seen as orthoclase
rims; however, in the Tertiary granodiorite porphyry, it appears as veinlet alteration with
selective replacement occurring only locally. Silica-rich intervals of ore occur as veinlet
controlled ± pervasive replacement of the host rock by quartz. Sericite is primarily found
as selectively replacing plagioclase feldspar, and occasionally in veinlets; however, in
neither case is the presence abundant. Primary interstitial biotite lenses can be seen
selectively altered to chlorite. These early hypogene alteration phases are masked by
younger supergene clays which replace the original plagioclase phenocrysts (altered
earlier to sericite) and dominate as fracture coatings with iron- and copper-oxides. Ironoxides (primarily hematite) are commonly found as boxworks after pyrite. Goethite,
hematite, and limonite are found replacing sulfide disseminations and in veinlets as well
as fracture coverings (transported stains and coatings). The fracture coatings are
commonly mixtures of clay and iron-oxides.
20
The underlying sulfide zone is dominated by both hypogene orthoclase-biotite and
quartz-sericite-pyrite assemblages. The Precambrian quartz monzonite hosts both
selective (orthoclase and chlorite) and pervasive styles (quartz flooding) while the
Tertiary granodiorite porphyry primarily shows veinlet controlled secondary orthoclase
and quartz as well as selective replacement of plagioclase with sericite. The mafic units,
Precambrian diabase and Tertiary andesite, show strong chloritization from weathering.
Calcite is present as a powdery fracture coating and in some cases as small rhombohedral
crystals. Gypsum is also present as a clear fracture coating and in small veins up to 4 mm
thick.
MINERALIZATION
Oxide zone minerals present include chrysocolla ((Cu,A1)2H2Si20sCOH)4 . nH20),
tenorite, neotocite, cuprite/chalcotrichite, native copper, copper-bearing clays, and trace
amounts of brochantite. The copper oxides, chrysocolla and tenorite, are present as veins
and fracture coatings. The copper-bearing clays occupy plagioclase feldspar sites as well
as coat fractures. The iron oxides present include goethite, hematite, and minor jarosite.
Locally, some of the hematite and goethite have been found to be copper-bearing. Iron
oxides are present as fracture coatings, gouge stains, and as stockwork veinlets. The
thickness of the oxide zone ranges from 30 to 400 meters with an average of 135 meters.
Sulfide zone minerals include hypogene chalcopyrite, pyrite, molybdenite, as well
as minor supergene chalcocite, covellite, and bornite. The pyrite: chalcopyrite ratio
21
averages 1 : 2. Sulfide minerals occur in several styles: grains disseminated throughout
rock matrix, in quartz veins and veinlets, smeared out as fracture coatings (usually with
chlorite). Occasionally, disseminated grains can be seen embedded in (replacing?)
biotite. Molybdenite is a late-stage minor constituent that often occurs as finely
disseminated grains within the selvages of quartz veins or associated with quartz-pyrite /
chalcopyrite veins.
The transition zone between the copper-oxides / silicates and sulfide
mineralization is highly irregular, ranging from less than 1 meter up to 20 meters in
thickness. Chalcocite in this interval is represented by a very thin and discontinuous
supergene blanket.
22
IN-SITU MINING
In situ leaching is a mining technique that has been studied for shallow copper
bodies since the early-1970's (USBM, 1989) and commercially practiced since the mid1970's as a method to produce uranium from a porous media (Millenacker, 1989). A
brief introduction to the mining technique and its advantages will be given here so that
the reader can fully understand the scope of this research project and the importance of its
results to the successful leaching of the oxide-ore from the Florence deposit. There are
numerous sources including Ahlness and Millenacker (1989), Dahl (1989), Marozas
(1989), Millenacker (1989), Millenacker (1989b), Paulson and Kuhlman (1989), USBM
(1989), Brink et ai. (1991), Gomer et ai. (1992), Nelson and Johnson (1994), Beane and
Ramey (1995), Ramey and Beane (1995); from which the reader can obtain more detailed
information about in situ mining.
In situ leach mining is an alternative approach for extracting metals from ore
deposits which may otherwise be unfeasible to mine with conventional techniques
(Gomer et aI. , 1992). The method, as it applies to the Florence deposit, is sometimes
referred to as "true" in situ mining (USBM, 1989) and involves the injection of sulfuric
acid through a series of injection wells. The acidic solution (raffinate) travels through the
ore body via mineralized fractures, dissolving and transporting copper along the way.
The copper-bearing solution (pregnant leach solution or PLS) is then pumped to the
surface by a set of recovery wells and piped to a solvent extraction electro-winning (SXEW) plant for processing. See Figure 3 for a schematic representation of the leaching
23
process. The advantages of in situ leach mining over conventional techniques (open pit
and underground) for copper recovery include less hazardous working conditions for
miners, lower environmental impact, and the ability to recover deep or low-grade ore that
would otherwise be economically unfeasible (Brink et aI., 1991).
Oxidized copper deposits are potential targets for in situ mining because of the
ease at which copper is leached with acidic solutions (Gomer et aI. , 1992). There are
several criteria which make the Florence deposit a favorable in situ target, including; 1)
Low acid-consuming host rock (Oracle Granite), 2) Rock is highly fractured
(~0.3
cm- I ) ,
3) The abundance of acid soluble chrysocolla and copper-bearing clays along the
fractures, and 4) The deposit is relatively low-grade (360 million tons of 0.24% AsCu)
and buried under approximately 100 meters of overburden. The percentage of acid
soluble copper (AsCu) refers to the grade of copper, as determined by BHP Copper's San
Manuel Method, which is readily leachable by dilute sulfuric acid.
24
Injection
Well
Recovery
Well
Processing Plant
Overburden
Ore Body
Figure 3. Schematic cross-section of an in situ mining system in which the ore is
removed by the injection of rafinate which selectively leaches copper from the
mineralized fractures, the PLS is then removed from the system through a series of
recovery wells and piped directly to a SX-EW plant for processing. See text for further
explanation. Figure is redrawn from USBM, 1989.
25
SCOPE OF RESEARCH
The Florence deposit is scheduled to be mined using state-of-the-art in situ mining
techniques. Therefore, this paper focuses on the geology of the Florence Deposit as
related to this mining process. With this in mind, two objectives were identified (1)
Determine the fracture controlled mineralogical configuration of the oxide zone in the
Florence porphyry copper deposit, (2) Determine the location and abundance of copper
mineralization as relevant to in situ mining techniques. The later objective involves both
the pre- and post-leach distribution of copper. Ore mineral chemistry is an important
consideration since the efficiency of metal recovery can be highly dependent on mineral
composition. Better estimates of copper recovery and, therefore, ore reserves can also be
achieved with sufficient knowledge of mineral chemistry (Brink et aI., 1991).
RELATED WORK
Preliminary results on the types of secondary mineralization present in the
Florence ore body are given in three separate reports, Eastoe (1996), Brewer and
LeAnderson (1996), and Davis (1996), and can be found in the geologic files at the
Florence office.
SAMPLE COLLECTION
Samples for this study were collected from three diamond drill holes 68-mf, 108mf, and 124-mf(Figure 2), that were mapped by the author. These three drill holes are
26
along a NE - SW cross-section of the first mine block and were chosen because they run
perpendicular to the main NW - SE trending Party Line Fault and associated structures.
This orientation was chosen because it provides the highest probability of revealing any
spatial variations of the fracture controlled mineralogy.
A systematic sampling protocol was designed to insure that any sample bias
would be avoided so that a true spatial distribution could be determined. Samples were
collected at 50 foot intervals from the top of the bedrock to 50 feet within the sulfide
zone. A 2 foot interval was chosen as the actual sample site (Figure 4) in which all
fractures were sampled for their representative mineralization. In the event of missing or
highly broken core at a pre-selected location, the sample site was moved downhole until
competent representative core was available. This sample program resulted in the
collection of 45 bulk samples from 45 sample sites.
Prior to removing any material from the fracture surfaces, observations were made
which include; lithology, number of fractures, percentage of phases present (based on
color) and habit, type of dominant fracture coating as a fraction, and number of fractures
bearing copper (based on color and/or presence of copper-oxides). The dominant fracture
coatings were assigned to one of five categories; chrysocolla, iron-oxide, clay, gypsum,
or none. These original sample descriptions can be found in Appendix A. Once all notes
were taken, the fractures were "scraped" or "picked" to remove the mineralization
present. Care was taken to avoid sample contamination by the inclusion of wall-rock
27
fragments. The samples resulting from this collection procedure consisted of powdery
mineral grains which were placed into 1 dram glass vials.
28
Overburden
68-mf
I08-mf
4
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4
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655
605
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4 .~
505
.
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455
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705
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••
••
._--_.__..
955
1-..__.._----_.._-_.._855
--
..
4 .~
4
Sulfide
.....__..
4
4
1005
__.-._-_ __ _.4 .~
4 .~
4
~
Oxide
...
-_._.
4 ~.
4
.
••
••
••
1055
4 .~
4 .~
......
.~
••
••
Bench Level
.~
4 ~.
_._-------- f-.-
..••
..
.
.
..••
. ••
. ••
. ••
.
.. ••
..••
. ••
Bedrock
124-mf
405
355
__._-_._--
.
305
....,,-_._-
255
205
'--
Sample Site (represents 2 vertical feet)
Figure 4. Diagramatic representation of the fifty-foot sample site spacing. Also
illustrated are the composite bench levels (in feet above sea-level) and the approximate
oxide-sulfide boundary. Note: Not drawn to scale.
29
FRACTURE DATA
The study of the fracture controlled mineralogy or the consideration of utilizing in
situ mining techniques cannot be justified without first understanding the fracturing of the
deposit. Fracture densities were calculated from the three core holes mapped for this
study using both the two-dimensional method described by Haynes (1984) and the more
common one-dimensional method. Fracture densities determined for every five-foot
interval are plotted in Figure 5. The dashed line and closed circles represent values
obtained by counting the number of fractures per foot of core and averaging the value
over a five foot interval. These values are then assigned a code based on the following
system: 1 = 0-5 fractures per foot, 2 = 6-10 fractures per foot, 3 = 11-15 fractures per
foot, 4 = greater than 15 fractures per foot, and 5 = fault gouge or breccia. The solid line
and closed squares represent values obtained using the two-dimensional method
described by Haynes (1984), which incorporates fracture orientations. Each data point
represents the average often 5-foot intervals (units were kept consistent with logging
convention). The average fracture densities are given in Table 1 for each of the core
holes studied.
Table 1. Average fracture densities for each drill hole.
Method
I-dimensional
n (5 feet)-l
2-dimensional
n (cm)-l
6S-mf
IOS-mf
124-mf
Average
>3
>4
>3
>3
.25
.29
.36
.30
30
68-mf
";"
E
~
c
:: 1
0.2
-
___ --- - - -e/
,,,I' ... --- --- ---
......... -- -- ...... -.
-I!;e
........ - --- ______
- 3 CII
2.f!
_1
0 ~______~________~______~________~__~O c
300
500
700
900
11 00
Depth in Drill Core (feet)
108-mf
Depth in Drill Core (feet)
124-mf
i :~ Tt--.~r-",--",-"--""---",,---------,,,,,=-~---------,'----''-----'-l! ~
300
500
700
900
1100
Depth in Drill Core (feet)
EXPLANATION
---. -- Data points for one dimensional method (right axis)
1 = 0-5 ft-,; 2 = 6-10 ft-,; 3 = 11-15 ft·,; 4 = > 15 ft-,; 5
= breccia or fault gouge
____ Data points for two dimensional method (left axis)
Each data p oint represents the average of ten values (50 feet of core)
Figure 5. Fracture densities plotted versus drill hole depth for each of the three core
holes sampled. The data gathered include both the one- and two-dimensional methods
(see text for explanation).
31
The average fracture density for the oxidized portion of the Florence porphyry
system is .30 cm- I or greater than 11 (5feet)-I , over the interval studied. The general
trends in fracture density are consistent with either method used. However, as Haynes
(1984) indicates, the quantitative two-dimensional method provides a more accurate
account of the actual fracture density over the more qualitative one-dimensional counting
method because the fracture orientation is considered in the calculation. This can be
justified by considering steep (vertical or near-vertical) fractures; a set of steep fractures
which parallel the drill core would lead to a lower density then would a set of nearly
horizontal fractures in drill core by the one-dimensional counting method.
Data from more than 12,000 digitized fractures collected from the BHTV in nine
drill holes indicate that the most prevalent fracture orientations are 230° - 320°, dipping
39.5° ± 10.2° W (Brewer, 1996). Further investigation shows the preferred orientation of
copper-bearing fractures to be 350° - 10°, dipping 40° to 20° W (Seguin, 1997).
32
METHODS OF STUDY
Two primary analytical techniques were employed in this study to aid in the
identification and determine the distribution of the fracture controlled mineralization, as
well as the distribution of the copper-bearing phases. The two methods used were X-ray
Powder Diffraction (XRD) and Scanning Electron Microscopy (SEM). In addition to the
aforementioned analytical techniques, detailed field observations were made when
mapping and sampling the drill core used in this study. The results of this project are
presented first individually by method and then later as a succinct compilation.
VISUAL INSPECTION
A total of 490 open fractures were described and sampled from the three drillholes that transect the Florence deposit. The fracture coatings were described based on
color and physical characteristics (Appendix A). Each fracture was then assigned to a
group based on its dominant coating (mineralization) type. The result ofthis grouping by
visual inspection indicate that the iron-oxides are the dominant fracture coating (45%),
followed by bare fractures (25%), clays (24%), gypsum ± calcite (4%), and chrysocolla
(2%). The fractures that were described as copper-bearing account for 19 percent of the
490 fractures described (Figure 6). The iron-oxide category includes goethite, hematite,
and jarosite. Bare fractures are those that lack megascopically significant secondary
minerals. The clay group includes all clays, whether they are copper-bearing or not. The
gypsum ± calcite and chrysocolla categories are those fractures which contain the
33
appropriate mineralization. The final category, combined copper, includes fractures that
contain chrysocolla, "eu-wad", and/or copper-bearing clay. The term "eu-wad" is used
to refer to phases which contain eu, Fe, and Mn in varying amounts and which do not
exhibit a distinguishable physical structure.
For the purpose of correlating across the drill hole profiles, all sample intervals
were converted to elevation above sea level (ASL) and then assigned to the appropriate
50 foot bench level (Figure 4). A schematic representation of the relative abundance's for
the dominant fracture coatings based on visual inspection, as a function of depth, are
given in Figure 7. Visual inspection indicates that the iron-oxides are consistently the
dominant fracture coating throughout the oxide zone of the deposit. Furthermore, where
the abundance of iron-oxides decrease, the clay contents increase accordingly. The
presence of chrysocolla is coincident with intervals of high clay content.
34
Number of Fractures Dominated by General Types
219
490 fractures were sampled
Ul
Q)
(,)
c:
~
...
::::I
(,)
(,)
0
0
...
Q)
.c
E
22
::::I
10
Z
x
0
Q)
LL
(ij
Q)
c
0
c
~
Q;
:o§:
:i:
Q)
5~
E o ( / ) ro
o u
a. 0
o
>-
Fracture coatings by general type
Figure 6. The number of occurrences for each of the general groups as noted during
sample collection. The categories represent only the dominant phase present over the
interval. Each category is explained in the text. See Appendix A for the original sample
descriptions.
35
...
Q)
Q.
0
u
.!!!
'0
0
(.)
0
...III
Q)
co
Oxide/Sulfide
Boundary
I/)
><
0
III
LL
U
Q)
>.
I/)
~
-'=
U
c
::s
I/)
Q.
>.
(!)
Q)
c
.c
E
0
U
,
Figure 7. Schematic representation of the observations made while collecting samples
(visual inspection) for all open fractures as a function of drill hole depth. The combined
copper category represents all the occurrences of chrysocolla and copper-bearing clays.
In general, calcite was usually present with the occurrence of gypsum. See text for
further explanation. The bar thickness is proportional to the general groups abundance.
The sample results from all three core holes were combined into bench levels as indicated
in Figure 4.
36
X-RAY POWDER DIFFRACTION
All of the samples were run by the author in the X-ray Diffraction Laboratory,
Geosciences Department, University of Arizona. The equipment used was a Siemen's D500 X-Ray Diffractometer equipped with a Siemen's Kompensograph X-T Paper Chart
Recorder. In order to maintain consistency, all ofthe samples were run with the machine
settings as given in Table 2.
Table 2. Diffractometer settings and constants used for all x-ray runs.
rnA: 30
kV: 40
Scan: 28 2°/min
Chart Speed: 2 em/min
Scale: Linear
Time Constant: 1 sec
Counter Tube: 964 v
Filter: Graphite Monochrometer
Diffractometer Beam Slit: 1°
Detector Slit: 0.15°
Measuring Range: 2x10 2 imp/sec
Target: Cu
Measuring Window: 3° 28 ---+ 70° 28
Sample Preparation
Each of the 45 bulk samples were examined under a binocular microscope and
again observations were made regarding mineral phases that may be present. Any
mineral fragments that were contaminants from the wall rock (i.e. quartz, feldspar,
biotite) were removed; if needed, the remaining portion was separated based on color. A
portion of each sample was then ground with an alumina mortar and pestle until it passed
37
through a 250 copper mesh sieve. The powder was then adhered to a 2 x 2 inch pyrex
slide with isopropyl alcohol and placed in the diffractometer.
A few representative samples thought to be "pure" clay were placed in a small
beaker with distilled water and submerged in an ultra sonic bath for approximately 15
minutes. The top portion of supernatant was removed with a pipette and placed onto a
2x2 inch pyrex slide and dried in an 40°C oven. This procedure was repeated until a
sufficient layer was present and then placed in the diffractometer. The settled portion was
also placed onto a slide and analyzed in the diffractometer.
A total of 65 samples (separated and non-separated) were analyzed and identified
by x-ray diffraction.
Identification Procedure
The positive identification of a mineral phase present in a heterogeneous sample is
extremely difficult, particularly for clay minerals. This is due, in most part, to the
overlapping of principal peaks with one another, as well as with other common minerals
such as quartz and the feldspar group. Another common problem with the XRD
identification of clay minerals is the tendency of a sample to become preferentially
oriented versus a randomly oriented sample. The effect of this is enhanced peak
intensities for the preferred planes (Brindley and Brown, 1980).
All of the diffractograms generated in this study were identified by hand by the
author using d-spacing data given in: ASTM (1967), Brindley and Brown (1980), Chen
38
(1977), and JCPDS (1974). The identification procedure for each diffractogram was
carried out as follows (1) The 28 angles were recorded on the chart paper, (2) The chart
was placed on top of diffractograms run for standards of the commonly occurring phases
(quartz, feldspars, goethite, hematite, and jarosite), these peaks if present were subtracted
out, (3) The remaining peaks (and the principal quartz peak) were entered into a
spreadsheet, (4) The spreadsheet corrected the 28 angle for the average machine error of 0.24 0 (by comparing the principal quartz peak of the standard to the position of the same
peak on the diffractogram), (5) The spreadsheet then converted the corrected 28 value to
d-spacing using the Bragg relationship: d = A/(2 sin 8), where A = 1.5418.
A final worksheet for each sample was printed bearing a table which lists all of
the unknown 28 angles (raw and corrected), the corresponding d-spacing, relative
intensity, and a blank column for identification notes. In addition, the sheet contained a
listing of the known peaks and the machine error correction factor. This worksheet was
then used to identify the sample by comparing the measured d-spacings with the dspacings published in the aforementioned references. The actual diffractogram was only
further utilized when it became necessary to confirm or deny the presence of a minor
peak.
It was known from previous work, Brewer and LeAnderson (1996), Eastoe
(1996), and Davis (1996) and observation made during the collecting procedure that the
majority of the fracture controlled mineralogy would be clay minerals, iron-oxides, and
copper-oxides; with this in mind certain identification criteria needed to be established.
39
Since it is not uncommon for clay minerals to be affected by humidity and occur in
various hydration states (Deer et aI., 1992) it was decided that a 28 window of ± 0.5 0
would be used to aid in identifying the measured XRD peaks. A list was compiled (Table
3) that gives the range of the d-spacing window used corresponding to a 28 window of ±
Table 3. The d-spacing window used to compare measured peaks with published peaks.
d-spacing (A)
1.5
1.75
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
7.0
10.0
15.0
20.0
d-spacing window (A)
± .011
±.016
±.021
± .034
± .049
±.068
±.089
± .113
± .140
± .170
± .203
± .276
±.567
± 1.28
±2.29
40
Owing to the heterogeneous nature of the samples and the inherent problem of
overlapping peaks among various mineral phases, it was necessary to establish a set of
criteria in order to consistently identify the unknown peaks. The determination of
whether a mineral phase was present or absent was established as given below in Table 4.
Table 4. Level of confidence in determining whether a mineral phase was present.
Identification
Present (P)
Probably Present (PP)
Maybe Present (MP)
Number of Principle
Peaks (from JCPDS)
3 0f3
20f 3
1 of3
Percentage of Remaining
Secondary Peaks Present
2 50
2 50
2 50
41
RESULTS-XRD
The mineral phases identified by x-ray diffraction are listed with their level of
confidence in Table 5. This list contains only the minerals present as actual secondary
fracture coatings, the occurrence of phases from wall-rock contamination have been
omitted (i.e. quartz, feldspars, biotite). The quantitative abundance of the various clay
,
minerals in a sample is difficult to determine and can be only 'at best' estimated by the
relative peak intensities and number of principle peaks present. The coding of "Present",
"Probably Present", and "Maybe Present" can also be used as an abundance qualifier.
Table 5. Minerals found as fracture coatings and level of confidence.
Occurrence*
Mineral Phase
14 A Montmorillonite
P-3, PP-4, MP-O
15 A Montmorillonite
P-14, PP-17, MP-6
P-5, PP-8, MP-3
18 A Montmorillonite
21 A Montmorillonite
P-5, PP-ll, MP-2
P-l, PP-3, MP-O
Mica-Montmorillonite
Illite-Montmorilloni te
P-4, PP-9, MP-2
P-3, PP-O, MP-O
Illite Group
P-14, PP-9, MP-3
Halloysite
Sepiolite
P-3, PP-4, MP-5
P-15, PP-7, MP-5
Kaolinite
P-4, PP-8, MP-O
Chrysocolla
P-2, PP-l, MP-O
Neotocite
Goethite
P-34, PP-O, MP-O
Hematite
P-24, PP-O, MP-O
P-14, PP-O, MP-O
Jarosite
Gypsum
P-6, PP-2, MP-2
Anhydrite
P-2, PP-l, MP-O
Calcite
P-4, PP-3, MP-l
Chlorite Group
P-l, PP-3, MP-l
*P=Present, PP=Probably Present, MP=Maybe Present
42
The x-ray diffraction identification of the 65 fracture-controlled sample separates
collected for this project indicate that there are 19 confirmed different mineral phases
present as fracture coatings. Refer to Appendix B for a listing of mineral phases
identified by drill hole. The distribution and relative abundance' s for all of the mineral
phases identified are illustrated in Figure 8. These results support the visual inspection
categories by confirming the dominance of the iron-bearing phases (goethite, hematite,
and jarosite), followed by the clays 15
A montmorillonite, halloysite, and kaolinite.
Table 6 lists the order of dominance for the clay minerals when considering only those
which are "Present" or "Probably Present". The phases identified by XRD are consistent
with those identified within an oxidized porphyry copper deposit in Santa Cruz, Pinal
County, Arizona by Brink et aI. , (1991).
The clay mineralogy is particularly important in an in situ leach mine because of
the potential for metal loss due to the exchange of cations between the acidic leach
solution and the ore-bearing clays (Gomer- et aI., 1992). Montmorillonite yields the
greatest potential for copper exchange (copper exchange capacity (CuEC)
~
47.0 meq per
100 g clay), whereas kaolinite poses the least threat of exchange in the leach environment
(CuEC
~
0.41 meq per 100 g clay) (Gomer et aI. , 1992).
Another concern during leaching is the encapsulation of a copper-bearing mineral
by a newly precipitated phase as the result of the leach solution reacting with the gangue
minerals in the deposit. In addition, the deposition of newly precipitated phases can
produce fracture-filling (Ramey and Beane, 1995) and greatly impede the flow of
43
raffinate through the system. These problems can occur when Ca+2 is removed from
montmorillonite and then reacts with the S04·2 in the leach solution to form gypsum.
44
Q)
~
c..
s:::
~
.2
.;::
0
....Es:::
0
:!:
Top of
Bedrock
Q)
~
s:::
0
ca
~
Q)
~
I/)
>-
.2
iU
::I:
.!!!
c..
~
...
0
C)
Q)
~
=
Q)
~
:2c..
Q)
"0
u
0
I/)
~
J:
Q)
~
u
Q)
~
.... ....
0
0
Q)
en u z
I
J:
Q)
0
C)
I
I
....
Q)
:;:;
Q)
~
I/)
Q)
..,
ca
E
::I:
...0
ca
E
~
I/)
c..
>-
C)
...0
C)
....
.;::
Q)
Q)
~
~
.2
U
u
ca
J:
I
•
I
Oxide/Sulfide
Boundary
I I I
Figure 8. Schematic representation of all the phases identified by x-ray diffraction for all
the mineralized fractures as a function of drill hole depth. The bar thickness is
proportional to the minerals abundance. The sample results from all three core holes
were combined into bench levels as indicated in Figure 4.
45
Table 6. Decreasing order of abundance (with number of occurrences)
for the ten different clay minerals identified by XRD.
15 A montmorillonite (31)
Halloysite (23)
Kaolinite (22)
21 A montmorillonite (16)
18 A montmorillonite (13)
Illite-Montmorillonite (13)
Chrysocolla (12)
14 A montmorillonite (7)
Sepiolite (7)
Mica-Montmorillonite (4)
Illite Group (3)
Distribution By Mineralogy
The XRD data obtained in this investigation indicate that in every sample interval
more than one clay mineral phase is present with, locally, as many as five different clays
appearing in one sample. The distribution of the dominant and most important phases
present are illustrated in the cross-section seen in Figure 9. This cross-section is the
same as the geology section in Figure 2, only now, the fracture controlled mineralogy has
been schematically represented as a series of overlays. The map indicates that there is no
apparent relationship between fracture mineralogy and rock type; due, in most part, to the
mineralogical similarity between the rock types. The mineralogical zoning is the result of
supergene leaching of the ore body. This can be seen by the horizontal nature of the
zones. The relative age of oxidation and subsequent secondary mineralization of the
deposit can be inferred from the map as well. Oxidation has occurred post-tilting
(oxide/sulfide line mimics topography) and pre-faulting (the majority of copper-oxide
46
mineralization is cut off by the Party Line Fault) of the deposit. Although not readily
depicted in the map, the fault zones are characteristically marked by zones of transported
goethite ± hematite stain on clay gouge.
47
LEGEND
II
II
II
!:' I
D
Montmorillonite
Chrysocolla
Kaolinite
Calcite ± Gypsum
Goethite ± Hematite
Figure 9. Generalized cross-section showing the distribution of the dominant fracture
controlled phases. Same section as in Figure 2 with mineralogy overlaying the geology.
The mineralization is depicted as a series of overlays, no timing or cross-cutting
relationships are implied by the illustration. Only the dominant phases identified in the
labeled diamond drill holes are considered. Except for small local intervals,
montmorillonite is ubiquitous. See text for further discussion. No vertical exaggeration.
48
SCANNING ELECTRON MICROSCOPY
Scanning electron microscopy was used on the fracture samples to see if there are
any physical relationships among the phases and electron-dispersive spectrometry was
used to determine the bulk chemical composition and relative weight percents of the
dominant elements present. Another point of interest was to determine how and where
the copper is distributed in the clays.
The samples were run by Gary Chandler, in the author' s presence, at the
Department of Materials Science and Engineering, University of Arizona. The
equipment used was a Hitachi S-4500 Field Emission Scanning Electron Microscope
equipped with a Noran Voyager EDX Microanalyzer. The machine specifications are
given in Table 7.
Table 7. Machine specifications for the FESEM and EDX Microanalyzer.
Electron Gun: Cold field emission electron source
Image Resolution: 1.5 nm or better at 15 ke V
4.0 nm or better at 1 keY
Magnification: 20 to 500,000 x
Acceleration Voltage: 0.5 to 30 kV (0.1 kV/step)
EDX Detector: Detects light elements, Z
~
5
Digital x-ray mapping capabilities
Interest in the fracture samples was divided into two areas: 1) The pre-leach bulk
chemistry and morphology, and 2) The post-leach bulk chemistry and morphology. The
49
first set of results deals only with those samples which were not treated with sulfuric acid
(pre-leach), followed by a section covering the results of the post-leach samples.
Sample Selection
Samples were selected for SEM examination which met the following criteria; 1)
Color representative of a "pure" end-member, 2) Morphology (size and shape) suitable
for mounting, and 3) Previously identified by XRD. A total of 5 samples from the drill
hole cross-section were examined and analyzed for elemental abundance under the SEM.
Two of the samples were representative of "pure" copper-bearing clay (shades of light
green and blue), one sample was "pure" chrysocolla (bright blue), one sample "pure"
iron-oxide (red-brown), and one sample represented a more common mixture of the
above.
Sample Preparation - Unleached
The samples were prepared by first selecting three grains or particles under a
binocular microscope which met the purity, size, and morphology requirements. The
ideal grains were 1-2 mm in diameter and "smooth". The grains were then mounted to an
SEM 'stub' (1 cm in diameter aluminum disc with a spigot for stage attachment) with
double-sided sticky tape. The sample 'stub' was then placed in a diode type sputter
coater where a coating (~150
A thick) of gold-palladium alloy was applied. This
50
conductive coating is applied to prevent charging under electron bombardment (Reed,
1996) and to enhance SEM imaging resolution (Purvis, 1991).
Sample Preparation - Leached
The samples were prepared by first weighing out 1 gram of material which was
checked under a binocular scope for homogeneity. The samples were then placed into
individual funnels lined with filter paper that were resting in Erlenmeyer flasks. Using a
solution : clay ratio of 40 ml : 1 gram (Gomer et aI., 1992), the samples were rinsed
initially with a pH = 3.21 raffinate. The rinse was completed three times in order to allow
the sample and solution to come to equilibrium, approximately 1 hour (Gomer et aI.,
1992). At the end of the one hour leaching cycle, a small portion of the sample was
removed from the funnel and placed onto an SEM mounting stub as described in the
previous section. The process was then repeated using a pH = 1.51 raffinate. A total of
four sample were treated in this process. Analysis were done on the raffinate prior to
leaching as well as on the PLS after leaching. The mineral samples were analyzed using
SEM.
51
RESULTS - SEM
Scanning electron microscopy of the 5 representative samples provided a detailed
look at the physical habits of the mineral phases present and their relationship with one
another. In addition, elemental analysis and mapping were done to provide a qualitative
relationship among the major elements associated with this environment. The minerals
identified using imaging and elemental data from scanning electron microscopy are listed
in table 8.
Table 8. Mineral phases identified using SEM.
Montmorillonite
Halloysite
Illite Group
Kaolinite
Chrysocolla
Hematite
Goethite
Apatite
Quartz
Image Recognition And Identification
The recognition and identification of the SEM images was possible with the aid of
elemental data and reference to the following resources; Bohor and Hughes (1971),
Henning and Storr (1986), Keller et al. (1986), and Robertson and Eggleton (1991). In
addition, insight from Gary Chandler and Richard Preece proved to be quite beneficial.
Inspection of the images shown in Figures 10 - 13 present evidence that the
minerals coating fractures are separate phases and can be readily distinguished from one
52
another at the scale of SEM examination. Any mixing of phases is slight enough so as to
not disturb the predicted morphology. There was very little evidence seen in this SEM
work that would suggest that separate phases are intergrown with one another.
53
Figure 10. SEM image of montmorillonite. A) This sample exhibits the typical 'comflake' habit and is characteristic of the majority of montmorillonite in the Florence
deposit. B) Montmorillonite with either halloysite or chrysocolla bound to the surface.
The 'stick-like' habit ofhalloysite can be difficult to distinguish from the porous
chrysocolla. Note scale and magnification. Scale length shown in lower right comer of all
SEM images.
54
Figure 11 .
occurrence IS highly
localized. B) Kaolinite with hematite on its surface. This blocky nature of kaolinite is
characteristic of the samples in the deposit. Hematite always occurs as drusy balls and is
attached to the surface of a clay. Note scale and magnification.
55
Figure 12. SEM image of a typical chrysocolla sample. The chrysocolla in the deposit
does show some variability as seen between this and figure 13a. In general, the samples
are all highly porous regardless of their chemical make-up. Note scale and magnification.
56
Figure 13. SEM images of chrysocolla. A) Shows the variation in porosity when
compared to figure 12. 8) An exploded view of image (A). Note scale
magnification.
57
EDS - Unleached Results
The SEM was equipped with an energy-dispersive (ED) x-ray spectrometer which
was used to gather data on the distribution of the major elements present in the
representative fracture-controlled mineral samples. The samples were divided into three
categories; 1) clay dominant, 2) chrysocolla dominant, and 3) hematite dominant. Table
9 lists the breakdown ofthe major elements for 19 analyses. The weight percent values
are automatically normalized to 100 percent by the spectrometer. The stoichiometries are
determined by varying the number of oxygens, depending on the main mineralization
type previously mentioned; with the assumption that all dominant phases have been
identified. The elemental abundance's produced by the ED spectrometer should only be
considered as semi-quantitative data. These numbers are based on a standardless analysis
and have all been 'normalized' to equal 100%. It is also recognized that the numbers can
be falsely intensified by 'reflections' from the surrounding area. This is particularly true
when the analyzed spot was not in topographic relief. Furthermore, the spectrometer only
identifies the elements requested, therefore, it is possible that other elements do occur in
measurable quantities.
58
Table 9. Elemental analyses of all unleached samples. Data are organized according to
their "dominant" category, based on visual inspection.
AnalysIs Numbe r "
EOS-I
Element
Si
0
K
Na
Mg
Ca
Cu
Fe
AI
EOS-l
EOS-J
Si
0
K
Na
Mg
Ca
Cu
Fe
AI
p
J<,U~-l
<
EOS-9
27.38
44.28
0.34
0.00
1.18
0.82
0.00
8.67
17.32
0.00
100.00
34.58
40.69
1.7 4
0 .00
0 .92
2.07
5.88
2.07
11.77
0.29
100 .00
33 .6 1
42.33
1.86
0 .00
0 .5 1
1.83
4 .25
3.18
12.42
0 .00
100 .00
33.28
42 .54
2.09
0 .00
1.50
1.43
4 .7 8
2.50
11.88
0.00
100 .00
27.51
49.9 1
3.83
0 .66
1.19
0.66
2.97
2.62
10.66
0.00
100 .00
32.02
38.3 1
0.49
0 .10
1.06
1.45
4 .5 1
9 .8 5
12 .22
0.00
100 .00
Stoic hiomet ry based on 10 oxygens
3.951
4 .071
4 .071
3.523
4 .841
10 .000 10 .000 10 .000 10 .000 10 .000
0 .05 1
0 .000
0 .000
0 .032
0 .174
0 .000
0 .000
0.000
0 .000
0.000
0. 176
0 .2 16
0 .262
0.262
0.148
0 .105
0. 112
0 .112
0.074
0 .203
0.389
0 .146
0.146
0.000
0 .364
0.561
0.146
1.388
0.103
1.388
2.320
1.716
1.925
1.557
1.925
0 .000
0.000
0.000
0 .037
sam p)Ies
4 .522
10 .000
0 .180
0.000
0 .079
0 .173
0.253
0.216
1.741
0.000
4.456
10 .000
0 .201
0.000
0 .23 2
0 .134
0.283
0.168
1.657
0.000
3.139
10 .000
0.3 14
0.091
0.158
0.052
0.150
0.150
1.267
0.000
4.427
10 .000
0.098
0.015
. 0.185
0 .138
0 .278
0 .575
1.874
0.005
100 .00
100.00
100.00
4 .7 56
10 .000
0.011
0.092
0.223
0.165
0.251
0 .38 5
1.818
6 .111
10 .000
0 .080
0 .000
0 .136
0 .158
0 .3 24
2.180
2.625
4 .829
10 .000
0.076
0 .000
0.170
0 .167
0 .555
0.091
2 .052
4 .856
10 .000
0 .055
0.000
0 .165
0.201
0.473
0.120
1.891
-
EOS-8
26.98
37.75
0 .00
0.00
1.50
1.05
2 .18
18 .29
12.25
0.00
100 .00
100.00
-
J<,U~-1.':
34 .24
40. 17
0.53
0.00
1.00
2.02
7.54
1.68
12.81
-
-
are
cia y aomlDant
31.27
45.10
0 .56
0 .00
1.48
1.19
6.9 6
1.61
11.84
100.00
Ana lysis Nu mber"
Element
Si
0
K
Na
Mg
Ca
Cu
Fe
AI
p
23.46
27 .6 3
0.00
0.00
0.83
1.76
43.37
0 .00
2.9 5
Total
Wt. %
Si
0
K
Na
Mg
Ca
Cu
Fe
AI
P
EOS-IJ
EOS-14
EOS-IS
25.35
13. 10
0 .20
0.00
0 .73
1.94
55.55
0 .10
3.02
-
100 .00
100 .00
1.451
3.000
0.000
0.000
0.059
0 .076
1.186
0 .000
0 .190
3 .308
3 .000
0.019
0 .000
0 .110
0 .178
3 .203
0 .007
0.411
-
-
• J',US-I, - J',US-Ib are
26 .21
37.16
0 .20
0.00
0.05
1.52
29.95
0.24
4.65
0.00
100 .00
3 oxygens
1.205
3.000
0.007
0000
0 .002
0 .049
0 .609
0 .006
0 .223
0 .000
EOS-II
EOS-7
38 .19
30.43
1.05
0 .26
0 .3 4
2.05
2 .94
19 .99
4.75
0.00
100.00
30 .79
28.70
0 .56
0 .00
0 .59
1.13
3.69
2 1.83
12.70
33 .48
39.50
0 .7 3
0 .00
1.02
1.65
8.70
1.25
13 .67
EOS-5
EOS-6
33.H5
40 .55
0 .11
0 .53
1.37
1.67
4.04
5.44
12.43
P
Total
Wt.%
EOS-4
EDS-16
Mean
24.41
20.37
0. 10
0.00
0.78
1.85
49.46
0 .05
2.99
EOS-17
24 .98
32.12
0.00
0.00
0.00
1.32
35.99
0.67
4.48
0.45
100 .00
100 .00
20.46
34 .9 5
1.04
0.89
0 .54
1.09
3.00
30 .8 3
6.49
0 .72
100 .00
1.330
3.000
0 .0 00
0 .000
0 .000
0.049
0 .847
0.018
0 .248
0.022
1.823
3.000
0.006
0 .000
0 .043
0.088
1.461
0.008
0 .2 68
0 .0 11
1.000
3.000
0.037
0 .053
0.030
0.038
0 .065
0 .7 58
0.3 30
0 .032
-
chrysocolla dommant
EDS-I7 - EDS-I9 "hematite dominant" samp le
samp le s
EOS- 18
EOS-1 9
5.28
27.06
0.17
4.4 7
0.33
0.16
1.29
60.25
1.0 I
Mean
100 .00
17.72
33. 10
1.05
1.86
0.34
0.88
1.7 5
38 .28
4 .66
0.56
100 .00
3 oxygens
1.256
0.333
3 .000
3.000
0.064
0.008
0.012
0.345
0 .008
0.024
0 .044
0.007
0.036
0 .019
1.914
0.548
0 .309
0.066
0 .01 7
-
0 .863
3 .000
0.036
0.137
0.021
0 .030
0.040
1.073
0.235
0.024
27.43
37.30
1.93
0.2 1
0 .16
1.37
0 .96
23.75
6.49
0.40
100 .00
-
EOS-IO
EOS-12
Mean
59
The SEM results support the identification conclusions from the XRD data.
Figure 14 is a ternary plot of the 19 analyses done on the unleached samples. The
stoichiometric end-member phase was plotted as a reference to the groups that appear in
the plot. The position of the chrysocolla end-member varies according to the formula
chosen from the literature. Both the montmorillonite and kaolinite samples appear to be
slightly deficient in silicon; whereas the chrysocolla analyses all fall between the two
end-member formulas. The most abundant clay examined by SEM is Camontmorillonite, followed by kaolinite and chrysocolla. Iron-oxides are abundant as
goethite or hematite. There do not appear to be any intergrowths of chrysocolla with
clay, and the 'green' color associated with the clays is associated copper occurring in the
structure of montmorillonite and kaolinite. Petit et aI., (1995) found strong evidence that
suggests a divalent copper cation can substitute for a trivalent aluminum cation in the
octahedral site of kaolinite. Based on stoichiometry and charge balance, it appears that
copper is located in the octahedral site within montmorillonites and not the exchangeable
site. Based on the Petit et ai. (1995) work on kaolinites, it appears that copper occurs in
the structure of the Florence kaolinites. Chrysocolla is common as a 'pure' phase, but
may also be present mixed with clay. It is possible that a transitional phase between
haUoysite and chrysocolla (Brindley and Brown, 1980) is present and yielding the' lightmoderate blue' clays.
60
Elemental mapping of the distribution of copper was done using the ED
spectrometer. The results showed the copper to be ubiquitous at every point in every
sample. These results support the conclusion that copper is located in the clay structure
and is not present as a physical mixture of clay and chrysocolla.
61
Si
•
*
Montmorillonite
(Na,Ca)O.3(Al,Mg)2Si40 I O(OH)2 . nH20
Kaolinite
AI,Si,Os(OH).
..•....
~ (;'~\./~
.':
e.\
From this study
End-member phase
Chrysocolla
(Cu,Al)2H2Si20S(OH)4 . nH20
...- ......•-.....
CuSi03 . 2H20
:'.
e·'···, .....-'.
Al+Fe
Cu+Mg+Ca
Figure 14. Ternary plot ofthe EDS data, as weight percents, gathered on all unleached
samples (19 analyses). The general groups outlined support the results obtained by x-ray
diffraction, which show montmorillonite phases as the dominant clay present followed by
kaolinite and chrysocolla. Note: The chrysocolla end-member point varies as indicated
by the formula used.
62
EDS - Leached Results
F our of the samples from the unleached group were selected to study the effects of
leaching with sulfuric acid. Figures 15 - 16 are SEM images of each sample after the
leach experiment. Changes in mineral morphology appear minimal, with only a
"smoothing" taking place. These 'mini' experiments were designed to mimic the
leaching process without introducing any effects from wall rock interaction. The results
of the analyses are given in table 10. The analyses are again grouped by dominant
mineralogy with the stoichiometry calculated accordingly. The unleached EDS results
are again tabulated for reference. The tabulated results are plotted on a stacked ternary
diagram (Figure 17). The figure shows: a) Analyses of a copper-bearing montmorillonite
sample and b) analyses of a "mixed" sample. The sample appears heterogeneous in hand
sample, but analyses indicate it is montmorillonite. Both samples (a) and (b) appear to
have leached stoichiometrically as indicated by the grouping of data points. The next
triangle (c) shows the analyses of a hematite-coated kaolinite sample. The leaching
nature of kaolinite is more sporadic and generally indeterminable by these data. Analyses
of a chrysocolla sample is given in (d). The chrysocolla analyzed in this experiment
represents the two common types seen, one is bright blue and densely crystalline and the
other is light-moderate blue and soft. The softer variety gives up its copper easily, as
indicated by the two data points off to the left. The other variety is more resistant to
leaching. Additional EDS data were obtained on this sample to verify the lack of leached
copper.
63
Figure 15. SEM images of montmorillonite after leaching with pH = 1.51 raffinate. A)
Sample originally described as "mixed" . B) Copper-bearing montmorillonite sample.
The flakes appear more rounded and smooth after leaching (compare with figure 10).
Note scale and magnification.
64
Figure 16. SEM images after leaching with pH = 1.51 raffinate. A) Chrysocolla shows
very little change in morphology (compare with figure 12). The web-like appearance
and porous texture remains. B) Hematite-coated kaolinite sample lacks the typical
blocky form and shows indications of breaking down (compare with figure 11 b). The
hematite appears unaltered. Note scale and magnification.
65
Table 10. Elemental analyses of all leached samples. Data are organized according to
their "dominant" category based on visual inspection.
Element
EDS-9
EDS-9.3
EDS-9.1
JWS-IO
Analysis Number·
EDS-10.3 EDS-I O.I EDS-II
EDS-11.3
33.61
0
44 .37
1.59
41.12
3.66
42 .33
K
40.69
1.74
1.86
1.5 7
2.01
2.09
1.94
5.55
3.83
2.65
2.91
Na
0.00
0.31
0.00
0.00
0.58
0.00
0.00
0.02
0.00
0.66
0.7 1
0.00
Mg
0.92
2.07
1.10
1.48
0.90
0.51
0.89
0.92
0.00
0.52
0. 19
1.50
1.43
5.88
7. 10
7.17
1.83
4.25
2.07
11.77
0.29
2.62
9.87
5.17
10.76
0.00
100.00
3. 18
12.42
0.00
6.78
2.91
11.06
0.22
5.25
2.40
11.04
0.57
100.00
100.00
100.00
1.553
4.522
4.230
3.559
3.998
3. 139
3.435
3.663
10.000
10.000
10.000
4.456
10.000
3.773
10.000
10.000
10.000
10.000
10.000
10.000
Ca
Cu
Fe
AI
P
Tolal
Wt.
100.00
0.26
100.00
42.54
45.62
EDS-I2.1
31.22
31.28
44.56
27 .5 I
EDS-I2.3
31.30
29 .84
47 .77
30.2 I
EDS-12
34.58
32 . 15
43 .3 1
33.28
EDS-II.I
Si
49.91
29 .18
48.39
30.38
47 .24
1.55
0.99
1.19
1.40
1.09
1.06
2.34
0.66
2.97
0.72
2.16
0.70
4.78
0.84
3.93
2.50
I 1.88
0.00
100.00
4.27
11 .56
0.04
100.00
3.71
10.25
0.25
100.00
2.62
10.66
000
100.00
2.94
11.55
0.32
100.00
2.53
3.78
11.09
0.28
100 .00
%
Sioichiomelry based on 10 oxygens
Si
4.84 1
4018
0
10.000
10.000
K
0.174
0.146
0.365
0. 180
0. 148
0. 172
0.201
0. 174
0.509
0.314
0.224
0.252
Na
0.000
0.047
0.000
0.000
0.094
0.000
0.000
0.004
0.000
0 .091
0. 102
0.000
0.079
0.173
0. 136
0. 172
0.016
0.277
0.232
0.134
0.144
1.371
0.062
Mg
0. 148
0.163
0.144
Ca
Cu
0.203
0.364
0.13 3
0.403
0.000
0.439
0.253
0.048
0.394
Fe
AI
P
0.146
0.170
0.361
0.216
0. 193
1.716
0.037
1.6 17
0.03 I
1.553
0.000
1.741
0.000
1.514
0.025
0.283
0.168
1.657
0.000
0.223
0. 146
0.158
0.073
0.217
0.095
0. 132
0.052
0. 150
0.190
0.059
O. I 52
0.059
0.1 12
0.268
0.239
1.364
0.029
0.150
1.267
0.000
0.174
1.416
0.034
0.135
0.229
1.503
0.005
1.391
0.031
• EDS-X - Sample before leaching
EDS-X.3 = Sample afler leaching wilh pH 3 rafinale
EDS-X.I = Sample after leaching wilh pH 1.5 rafinale
Elemenl EDS-15
EDS-15.J
EDS-15.1
EDS-16
AnalysIs Number·
EDS-16.J EDS-16.1 EDS-17
EDS-17.3
EDS-17.1
EDS-IS
EDS-IS.3
EDS-IS.I
Si
26.21
25 .60
29.79
24.98
27 .58
28.33
20.46
22.79
21.63
27.43
2U.26
25.96
0
37. 16
38.6 1
45 .90
32.12
46.4 I
39.28
34.95
47.58
35 .33
37.30
41.61
47.56
K
0.20
0.03
0.20
1.80
Ca
Cu
28 . 12
Fe
1.52
29 .95
0.24
8.46
0.39
1.32
35.99
0.67
1.23
9.85
1.64
0.21
1.32
22 .90
0.52
0.27
0.21
0.00
0.22
0.49
1.66
1.78
3.05
0.00
0.46
0.10
1.04
0.89
0.54
1.93
0.00
0.45
0.78
4.27
0.84
1.71
0.00
0.05
0.45
075
1.16
Na
Mg
0.00
0.00
3.40
1.47
10.96
0.53
2.93
27.68
AI
P
4.65
0.00
14.69
0.00
4.48
0.45
10.27
0.00
11.91
0.02
8.83
0.57
100.00
100.00
0.89
5. 16
100.00
0.36
100 .00
0
1.205
3.000
1.131
3.000
K
Na
Mg
0.007
0.000
0.002
0.001
0.000
Ca
Cu
Fe
Al
P
0.049
0.609
0.006
Tolal
1.09
3.00
0.00
2.37
30 .83
6.49
100.00
0.48
100.00
0.72
100.00
100.00
100.00
0.16
1.37
0.96
23.75
6.49
0.40
100.00
1.25
1.30
0.00
23.73
0.00
0.74
0.99
1.61
7.88
0.54
8.93
10.99
0. 17
100.00
100.00
WI. %
30xygens
J oxygens
Si
0.223
0.000
0.023
0.D25
0.550
0.020
0.238
0.014
1.109
1.330
1.0 16
1.233
1.000
0.819
1.046
1.256
0.832
0.933
3.000
0.005
3.000
0.000
3.000
3.000
0.133
3.000
3.000
0.030
3.000
3.000
0.049
3.000
0.060
3000
0.064
0.000
0.020
0000
0.000
0.010
0.020
0.031
0.015
0.012
0.089
0.059
0.000
0.031
0.003
0.139
0.049
0.032
0.847
0.018
0.248
0.022
0. 16 1
0.030
0.394
0.000
0.007
0.569
0.000
0.0 12
0.034
0.077
0.045
0.01 I
0.040
0.440
0.000
0. 107
0.0 19
0.037
0.053
0.030
0.038
0.086
0.018
0.065
0.758
0.023
0. 198
0.330
0.032
0.446
0.00 1
0.063
0.674
0.445
0.D25
0.008
0.044
0.079
0.037
0.D25
0.019
0.548
0.000
0.490
0.026
0. 161
0.309
0.017
0.337
0.020
0.4 1 I
0.006
66
Si
•
Original sample
•
After pH 3 rinse
•
After pH 1.5 rinse
AI+Fe
Cu + Mg+Ca
Figure 17. Ternary plot ofthe EDS data gathered prior to and during leaching
experiments. The sample groups are the same as those represented in figure 14. (a)
Analyses of a copper-bearing montmorillonite sample. (b) Analyses of a "mixed"
sample. (c) Analyses of a hematite-coated kaolinite sample. (d) Analyses of a chrysocolla
sample. See text for explanation.
67
Leach Solution
The solution concentrations were measured in the raffinate prior to the leach
experiments and again in the pregnant leach solution (PLS) after the leaching simulation
in order to determine any changes in chemistry from the breakdown of the clay samples.
The concentrations were converted to molarity and then plotted on Figure 18 along with
pH.
Graph (A) is of the analysis from the chrysocolla sample. This sample showed
the greatest change in pre- and post-leach concentrations, particularly for copper. The pH
also increased by a 0.1 pH unit. The increase in copper concentration in the PLS supports
the observation of a decrease in copper for the chrysocolla sample as plotted in the
stacked ternary in the previous section. The remaining graphs (B - D) show very little
change in solution chemistry. One noticeable change is the minor increase in pH which
indicates that some dissolution reactions were taking place. Each PLS analyses shows a
slight increase in the concentrations of sulfate, sodium, and calcium. Brewer (in prep.)
obtained similar results in column test experiments, run over a period of seventy-seven
days, using recycled raffinate on mineralized fracture surfaces. This could lead to
leaching problems as precipitating gypsum from the PLS could potentially close off the
fractures and prevent solution transport.
~
0.1
~
~
~
~
Q
N
~
~
0
N
rn
~
Major Dissolved Components
U
rn
0
a.
0
U
_
U
rn
~
~
~
0
N
~
N
z
rn
~
t
N
~
M
~
~
~
0
~
Major Dissolved Components
~
a.
0
0
~
0.0001
1.5
2
0.5
:J
-~
1.511.54
0.001
0.01
~
~
_
~
~
.pH
. 610-612
o Pre-leach
c.
::I:
1.
• pH
807
o Pre-leach
Comparison of Rafinate and PLS from a Leached
Copper-Bearing Montmorillonite Sample
U
:J
0.5
~ 1
~ 1.5
- i'. i'- :'-'
~ N
z
t M~
---~~-r:.--I-. rII
~
0.0001 .ICW " · ,' · " - :' . ,' . ,' a :,
0.001
0.01
~
~
'0
E
f/J
G>
c.
~
G>
~
~
'0
E
f/J
G>
c.
~
;
- - - - - - -F-.
1.511 .53
'I--+-~
.,..
I 1 ~
,_ ._ _ _.__ _.0.5
I· 1.5
D.
0.0001
0.001
0.01
_
~
~
:J~
U
~
Q
~
~
0
~~NN
~
t
~
~
a.
0
rn~NM
z
Major Dissolved Components
rn
U
U
_
~
:J~
~
~
Q
~
~
0
~~NN
z
t
~
~
a.
0
rn~NM
Major Dissolved Components
U
rn
o
0.5
1
1.5
2
C.
::I:
o Pre-leach
o Pre-leach
• pH
.683-685
• pH
. 533-535
Comparison of Rafinate and PLS from a Leached
"mixed" Sample
0.1
B.
0.0001 ,no : I I I I : I I i i I : I I : I I i i I : I I i rw ,I I , 0
0.001
0.01
0.1
, -__________________________---.,-, 2
Comparison of Rafinate and PLS from a Leached
Hematite-Coated Kaolinte Sample
Figure 18. The molarity of the major dissolved components and the pH for the initial raffinate and the resultant pregnant leach
solution for each of the samples. A) Solution analysis from the chrysocolla sample. B) Solution analysis from the hematitecoated kaolinite sample. C) Solution analysis from the copper-bearing montmorillonite sample. D) Solution analysis from the
mixed sample. See text for explanation.
C.
'0
E
f/J
G>
c.
~
;
~
A.
'0
E
f/J
G>
c.
G>
~
~
.---~~----------------------r2
Comparison of Rafinate and PLS from a Leached
Chrysocolla Sample
00
0\
69
ASSAY DATA
Acid Soluble Copper assays were collected at 10 foot intervals on drill hole 68-mf
and S foot intervals on drill holes 108-mf and 124-mf. This data were used in
conjunction with the known fracture controlled mineralogical framework to determine if
any correlation's could be made between grade and fracture mineralization. Table 11
lists the acid soluble copper values for intervals which are dominated by the main copperbearing phases within the deposit; montmorillonite, kaolinite, and chrysocolla. The
average acid soluble copper assays are 0.30%, O.2S%, and 0.36%, respectfully. Each
category hosts grades which are above the deposit average of 0.24%.
A T-test was run between each of the groups to determine the probability that the
assays came from the same population (i.e. interval). This proved to be indeterminate as
the probability values for the sets montmorillonite - kaolinite and montmorillonite chrysocolla are approximately O.S. Thus, there is a SO% chance that the populations are
the same. The only possible distinction is between kaolinite - chrysocolla, in which the
probability value indicates that there is only a 20% chance the populations are the same.
The idea of separate populations is supported by the higher average grade for the
chrysocolla dominated intervals, which would be expected. The relatively high average
grades for these intervals may only be in part due to the fracture mineralization. There is
a great deal of copper that is associated with altered plagioclase sites, microbreccia
fillings, and in the goethite structure as determined during this study and from data
gathered from the Santa Cruz Project in Pinal County, Arizona (Brink et aI., 1991).
70
Table 11 . The acid soluble copper assay percentage corresponding to intervals of
dominant clay-type mineralization occurring within that sample interval. The results of a
students T-test are also listed at the bottom of the table and discussed in the text.
Acid Soluble Copper Assays (%)
Montmorillonite Kaolinite Chrysocolla
0.78
0.09
0.09
0.13
0.30
0.67
0.30
0.02
0.35
0.01
0.35
0.25
0.67
0.25
0.41
0.02
0.12
0.49
0.07
0.22
0.30
0.25
0.66
0.12
0.16
0.22
0.30
0.41
0.41
0.38
0.15
0.79
0.19
0.26
0.49
0.31
0.24
0.16
0.30
0.41
0.12
MEAN
0.30
0.36
0.25
VARIANCE
0.034
0.049
0.029
PROBABILITY VALVES
mont-kao
kao-chrys mont-chrys
0.194
0.494
0.512
71
MINERALOGY DISCUSSION
This section includes information on the occurrence, abundance, hand-specimen
recognition or special information on each of the phases identified in this study. The
reader is referred to Appendix B as a reference to the bench levels given in the following
paragraphs.
MONTMORILLONITE
According to Deer et al. (1992), the effective basal spacing of montmorillonite
can be continous between 10 and 21A depending on the amount ofinterlayer water and
the nature of cation; for this reason, all the phases of montmorillonite have been grouped
together for purpose of discussion. The various hydration states of montmorillonite
dominate the known clay portion of fracture controlled mineralization in the Florence
deposit. Fifteen angstrom Ca-montmorillonite is the dominant copper-bearing phase with
Cu either exchanging for Mg or Al in the octahedral site. The dominant occurrence of
montmorillonite is in benches 655-455. Hand-specimen recognition of this mineral phase
is not currently possible. It can, however, be generally distinguished from kaolinite by
touching it to your tongue and seeing if it ' sticks' (i.e. if it pulls the water from your
tongue).
72
HALLOYSITE
The halloysite structure has the capability of bearing copper, at low copper
concentrations, as Cu or Cu and H can substitute for Al (Brindley and Brown, 1980). The
extent of copper-bearing halloysite was not determined from this study. Halloysite is,
however, present as seen in SEM imaging and XRD data. Two zones of abundance do
exist, they are the 755-655 and 555-455 benches. Hand-specimen recognition ofthis
mineral phase is not currently possible.
KAOLINITE
It is likely that kaolinite contains copper within its crystal structure at Florence.
Petit et ai., (1995) have shown copper to be stable in the octahedral (AI) site within
kaolinite. Kaolinite occurs relatively uniformly throughout the depth of the interval
studied. Two points of high occurrence are present, one at bench 855-805 and one at
bench 555-505. These points correspond to an increased occurrence of the copperoxides, whose distribution pattern closely matches that of kaolinite. The occurrence of
these two matching intervals may indicate that chrysocolla favors the presence of
kaolinite or vice-versa. Hand-specimen recognition of this mineral phase is not currently
possible, except where distinguished from montmorillonite as previously described.
73
ILLITE GROUP
The illite group has an irregular distribution at Florence, but appears to favor the
upper portion of the oxide zone. Illite group minerals have also been identified by Brink
et aI., (1991) in the Santa Cruz porphyry copper system. Hand-specimen recognition of
this mineral phase is not currently possible.
SEPIOLITE
Sepiolite is the least abundant of the clay mineral fracture coatings. It too occurs
randomly throughout the depth of the oxide zone. Other than being completely absent
beneath the 455 bench (also where the copper-oxides drop out - transition zone), the
significance of its presence is unknown. Hand-specimen recognition of this mineral
phase is not currently possible.
CHRYSOCOLLA AND NEOTOCITE
The distribution of chrysocolla (neotocite was only present in 2 samples) is fairly
uniform throughout the oxide zone with the exception of the 855-805 bench, which
shows a drastic increase in occurrence. As reported above, the increased occurrence for
the combined copper-oxides correspond to an increase in the occurrence of kaolinite,
however, the significance of this relationship is unclear at this time. The chrysocolla is
present as both a "pure" crystalline phase and as a mixture with clay, based on sample
color and hardness and Brindley and Brown (1980). Chrysocolla generally occurs in one
74
of three forms; 1) CuSi0 3 . 2H20, 2) CU3Si20s(OH)4, or 3) (Cu,AI)2H2ShOs(OH)4 .
nH20. The identification of chrysocolla (and neotocite) can be confidently made in handspeCImen.
GOETHITE, HEMATITE, AND JAROSITE
The distribution of the combined iron-oxides (goethite, hematite, and including
jarosite) is generally as predicted. The iron-oxides are abundant near the upper "leached
cap" of the deposit and decrease steadily down to the oxide-sulfide boundary. The three
low occurrences at benches 955-905, 855-805, and 805-755 is manifested by the
distribution of all the known pertinent fracture coatings (Figure 8). Bench 955-905 and
bench 805-755 show a decrease in occurrence for all mineral phases present as fracture
coatings; and bench 855-805 shows a marked increase in all mineral phases, particularly
copper-oxides. The goethite samples commonly will plate copper on a steel nail after
applying dilute HCI. Copper-bearing goethites have also been recognized in the Santa
Cruz porphyry copper system (Brink et aI., 1991). The majority of the iron-oxides are not
likely to be clay minerals with iron-staining, but rather they are actual oxide minerals.
The identification of goethite, hematite, and jarosite can be made with confidence in
hand -specimen.
75
GYPSUM, CALCITE, ANHYDRITE, AND CHLORITE GROUP
The occurrence of gypsum, calcite, anhydrite, and chlorite group minerals is
generally as predicted; each of these minerals are commonly found as fracture coatings
only in the transition and sulfide zones. These minerals, in order of abundance; gypsum,
calcite, anhydrite, and chlorite group, can all be confidently identified in hand-specimen.
76
CONCLUSIONS
The fracture controlled mineralogy of the Florence porphyry copper deposit
shows no variability horizontally within the cross-section studied and only local
variations occur between drill holes. The vertical distribution appears to be controlled
initially by supergene processes and faulting. The oxide zone mineralization studied is a
direct result of an earlier supergene sulfide blanket that has undergone subsequent
leaching, leaving only oxide and silicate copper minerals behind. The clays, iron-oxides,
and chrysocolla are uniformly distributed. The dominant fracture coating present is
goethite (usually copper-bearing) and occurs down to the transition zone between the
oxide and sulfide zones. When goethite and hematite occur together, goethite is always
the dominant phase. The dominant clay is 15
A montmorillonite with copper residing in
the octahedral site. Although montmorillonite is more abundant, the majority of copper
in the Florence deposit is in the form of chrysocolla. Multiple clays can be present on
any given fracture and there appears to be no correlation between color and clay type.
The XRD data and visual descriptions allow the following identification
guidelines to be suggested for the fracture controlled mineral occurrences:
~
•
Shades of green
copper-bearing clay
•
Shades of light-moderate blue
•
Shades of bright-moderate blue
•
Shades of black ~ neotocite, or 'eu-wad'
•
Shades of brown, red-brown, orange-brown ~ goethite
~
clay + chrysocolla
~
chrysocolla
77
•
Shades of dark red ----+ hematite
•
Shades of yellow-gray ----+ jarosite ± goethite
This information provides the geologist inspecting the fracture coatings a guideline and
level of confidence when describing these phases in hand-specimen.
SEM data and images indicate that the copper-bearing clay minerals occur as
distinct phases, with no evidence of intergrowths between chrysocolla and clay. The
leaching experiments showed chrysocolla to be the only phase that efficiently leaches
copper from its structure. The montmorillonite and kaolinite samples appear to leach
stoichiometrically, if they indeed reached equilibrium.
The degree and nature (chrysocolla) of fracture mineralization, high fracture
density (.30 cm- I or greater than 11 (5feet)-I), and low acid consuming host rock (Oracle
Granite) are important components to the successful in situ leaching of copper from the
Florence porphyry system.
78
APPENDIX A: Original Bulk Sample Descriptions.
Drill hole 68-mf: Sample descriptions, based on visual inspection.
Type of Dominan Total Fractures I
Fracture Coatin oated wI Coppe
0/8 CHRYS
0/8
5/8 GOE
0/8 Clay
3/8 None
0/11 CHRYS
0/11
6/11 GOE
0/11 Clay
5/11 None
O%CHRYS
5%
30%GOE
10% Clay
60% None
40% olive gn-gy, dense platy-blocky, xtln, slip?, Cu-c1ay?
O%CHRYS
40%
40% rd-orng-brn, dense platy, xtln, slip?, GOE-Clay?
20%GOE
20% It seafoam gn, powdery mass, Cu-clay?
40% Clay
Note: # of fracs not determined - breccia zone
40% None
80% yl-gy, thin, dendritic, powdery, JAR?+I-GOE?
0/9 CHRYS
0/9
20% deep rd-maroon, powdery-slightly xtln, sparse, HEM?
5/9 GOE
0/9 Clay
Note: good sample ofyl-gy mineral
4/9 None
2/10CHRYS
2/10
40% pale rd-brn, flaky, platy coating, GOE+I-HEM?
30% pale seafoam gn-blu, thin, powdery, dissem. , Clay+I-CHRY
4/10 GOE
2110 Clay
30% orng-brn, powdery, platy, assoc. wI gn-blu min. , GOE?
2110 None
0/12CHRYS
0/12
30% firey orng, thin powdery coating-stain, GOE+I-JAR?
60% deep maroon-rd, thin powdery coating-stain, no plate, HEM
7/12 GOE
3112 Clay
10% crmy-gy-yl, thin flaky crust, sparse, Clay?
2/12 None
20% yl-brn, flaky coating (2mm), slip?, GOE+I-JAR?
O%CHRYS
50%
40%GOE
40% It seafoam gn , powdery, massive, Plag sites & fracs, Cu-cla
50% Clay
40% deep maroon-rd, thin stain, HEM?
10% None
Note: # of fracs not determined - breccia zone
0/14 CHRYS
5/14
5% brick rd-orng, thin flaky , minor qty, JAR+I-GOE+I-HEM?
4/14 GOE
50% gn-yl-gy, powdery, platy coating, Cu-c1ay?
5/14 Clay
30% yl-brn, v. thin powdery stain, dissem., JAR+I-GOE?
2114 BIO
10% rd-brn, thin stain, HEM+I-GOE?
3/14 None
5% BIO partially altered to CHL
Sorted sample of brick rd-orng mineral
Sample Numbe Lithology % Phases Present and Observations
68/383-385
Yqm
49% brn-orng (GOE color), v. thin microxtln stain, GOE?
49% deep maroon-rd , stain, HEM+I-GOE?
2% shreddy secondary BIO
Note: mineralization v. weak, present only as stains
68/433-435
Yqm
70% deep rd-maroon-brn, powdery-stain, HEM+I-GOE?
10% gy-yl, dendritic powder, JAR?
20% orng-brn, thin sparse, powdery-stain, GOE?
Note: mineralization not abnt
68/483-485
Yqm
40% It gn-gy, powder, Cu-c1ay?
60% pink-rd-crm, powdery clay, HEM+I-Clay+I-GOE?
Note: # of fracs not determined - breccia zone
68/533-535
Yqm
68/583-585
Yqm
68/633-635
Yqm
68/683-685
Yqm
68/733-735
Yqm
68/783-785a
Yqm
68/783-785
79
Drill hole 68-mf, cont.: Sample descriptions, based on visual inspection.
Type of Dominan Total Fractures I
Fracture Coatin oated w/ Coppe
0112 CHRYS
3112
7112 GOE
3/12 Clay
2112 None
0/8 CHRYS
0/8
5/8 GOE
0/8 Clay
1/8 GYPS
2/8 None
Yqm
68/933-935
5% c1r-wht, fibrous xtls, GYPS
O%CHRYS
0%
(transition)
40% orng-brn-rd, platy, flaky, layers, HEM+/-GOE+/-JAR?
28%GOE
20% gy-gn, platy, layers, CHL-clay?
70% Clay
35% crm-gy, platy, flaky , layers, Clay?
2% GYPS
0% None
100% wht, thin, scarce powdery coating, Clay?, GYPS?
O%CHRYS
68/983-985
Tgdp
0%
(sulfide)
Note: frac mineralization v. minimal , highly frac - # not determin
O%GOE
trace amount of calcite may be present
30% Clay
30% GYPS
40% None
6811033-1035 Tgdp/Yqm 100% wht, thin scarce powder coating, Clay? GYPS?
0/8 CHRYS
0/8
(sulfide)
Note: frac min. v. minor, trace amount of calcite may be present
0/8 GOE
3/8 Clay
3/8 GYPS
2/8 None
Sample Numbe Litholo2V % Phases Present and Observations
68/833-835
Yqm
5% gy-yl , powdery patches, dissem ., JAR?
10% pale blu-gn, thin, powdery, platy, Cu-c1ay?
25% orng-brn, thick powdery coating and stain, GOE+/-JAR?
60% deep maroon-brn, thin stain, HEM+/-GOE?
68/883-885
Ta
85% deep maroon-rd, v. thin but abnt stain, no plate, HEM?
5% wht-crm, blocky thick coating, GYPS
10% dk gy-gn, platy, dense, CHL-c1ay?
Note: All fracs have minor xtln calcite
80
Drill hole 108-mf: Sample descriptions, based on visual inspection.
Type of Dominan Total Fracturesl
Sample Numbe Lithology % Phases Present and Observations
Fracture Coatin oated wI Coppe
108/373-375
Yqm
60% omg-bm-yl, platy, dense, stain, GOE?
118 CHRYS
3/8
20% blk, thin stain, spotty-blotches, TEN?, NEO?
3/8 GOE
20% gn-blu-gy, thin platy, xtin, Cu (CHYRS)-bearing Clays
2/8 Clay
2/8 None
108/423-425
Yqm
70% yl-gy, thin scattered powder, JAR?
I? CHRYS
0
30% deep rd-bm, disseminated powder, vug filling, HEM?
I? GOE (60%)
Note: Zone is highly fractured - not quantifiable
I? Clay
I? None (40%)
Yqm
108/473-475
50% rd-brn, thin, powdery-dense, platy, HEM?
0/ 12 CHRYS
0/ 12
40% brn-orng, thin, platy, GOE?
7/ 12 GOE
10% yl-gy, thin, powdery, platy, JAR?+/-Clay?
2/ 12 Clay
Note: Highly fractured - difficult to sample
3112 None
108/523-525
No sample, zone is all rubble
108/543-545
Yqm
80% yl-gy, thin, powdery, sparse, JAR?+/-Clay?
0/10 CHRYS
0110
20% rd-bm, v thin stain, GOE?
3/ 10 GOE
1/ 10 Clay
6/ 10 None
108/573-575
Yqm
108/623-625
Tgdp
108/673-675
Tgdp
60% orng-brn, platy, dense, thin, GOE?
20% deep rd-bm, thin, sparse, stain, HEM?
15% yl-gy, thin, powdery, sparse, JAR?+/-Clay?
5% blu-gn, xtin, small "patches", platy, CHRYS?
85% It seafoam gn, platy-powdery, Cu-Clay?
10% deep rd-bm, thin stain, slightly powdery, HEM?
5% blk, small scattered blebs, TEN?, NEO?
85% deep bm-rd, thin stain, HEM+/-GOE? (difficult to samp
10% It seafoam gn, thick (2-3mm), platy -xtin, Cu-Clay?
5% bm, thin, platy - xtln, GOE? *Iayered with 10% gn min
108/723-725
Tgdp+Yqm 70% orng-bm, thin, powdery-stain, GOE?
20% rd-brn, thin stain, HEM?
10% It blu-gn-gy, powdery-xtln, thick but sparse, Cu-Clay?
108/773-775
Tgdp+Yqm 50% orng-bm, v thin, platy, extensive, GOE?
40% army gn-gy, platy, dense, CHL?
10% It yl -gn-gy, thin, platy, dense, powdery, Cu-Clay?
108/823-825
108/828-830
No sample
Yqm+Tgdp 50% orng-brn, thin, platy-stain, GOE?
45% It blu-gn. thin, powdery, patches, Cu-Clay?
5% It gn-blu, thin, sparse, powder-xtin, Clay+/-Chrys?
118CHRYS
4/8 GOE
1/8 Clay
2/8 None
1/9 CHRYS
2/9 GOE
5/9 Clay
119 None
0/10 CHRYS
7/ 10 GOE
1110 Clay
2110 None
0/9 CHRYS
6/9 GOE
1/9 Clay
2/9 None
0/7 CHRYS
3/7 GOE
2/7 Clay
2/7 None
1I8CHRYS
3/8 GOE
2/8 Clay
2/8 None
118
6/9
1/ 10
1/9
2/7
3/8
81
Drill hole 108-mf, cont.: Sample descriptions, based on visual inspection.
~ample Numbe
108/873-875
Lithology % Phases Present and Observations
Yqm+Tgdp 70% orng-bro, thin, platy, crust, GOE?
30% It seafoam gn, sparse, thin, powder, Cu-Clay?
108/923-925
sulfide zone
Tgdp+Yqm 80% c\r, thin plates, GYPS?
20% milky wht-gy, shiny, thin covering, SER?
108/973-975
sulfide zone
Tgdp
50% dr, thin plates, GYPS?
50% milky wht-gy, shiny, thin, powdery, smooth, SER?
Type of Dominan Total Fractures I
Fracture Coatin oated w/ Coppe
0/ 12 CHRYS
3/ 12
7/ 12 GOE
3/ 12 Clay
2/12 None
0/6 CHRYS
0/6
0/6 GOE
2/6 Clay/SER
3/6 GYPS
116 None
015 CHRYS
015
015 GOE
2/5 Clay/SER
2/5 GYPS
1/5 None
82
Drill hole 124-mf: Sample descriptions, based on visual inspection.
I
ample Numbe Lithology % Phases Present and Observations
114/36U-362
rqm I)'Yo amy mustara yl, v. thin, powaery, Jar.
5% It pI gn, v. thin, powdery, platy, Clay?
10% firey orng-rd, v. thin, powdery, Goe+lar+Hem?
40% maroon-brn, dense, stain, Hem+Goe?
40% dull brn-rd, dense, stain, Goe?
124/410-412
Yqm
55% brn, platy, xtln-powdery, Goe?
40% maroon-brn, dense, stain, Hem+Goe?
5% It blu-gn-gry, powdery, Clay?
124/460-462
124/510-512
Yqm
10% pI yl-gn, xtln-powdery, thin, Cu-cIay?
(altered) 60% brn-yl, xtln, stain, Goe?
30% deep brn-rd, sporatic, stain, Hem?
Tgdp
ype 01 uomman lmal Fracmresl
racture Coatin oated w/ Coppe
U/ L:J Lnrys
LI I )
11115 Goe
2/15 Clay
2/15 None
0/14 Chrys
11/14 Goe
1/14 Clay
2/14 None
0/12 Chrys
7/12 Goe
3/12 Clay
2/12 None
0/16 Chrys
12/16 Goe
2/16 Clay
2/16 None
2% pI seafoam gn, powdery cavity filling, Cu-cIay?
2% blk, thin discon sporatic blebs, slightly mag, Mag?
6% yl-gy, v. thin powdery coating, Jar?, Lim?
60% maroon-brn, gen xtln stain, spots powdery, Hem+
30% orng-brn, thin powdery, usually rimming above, Goe?
124/560-562
Not enough core
124/565-567
Tgdp
60% maroon-brn, thin, abnt, dense, xtln stain, Hem+Go
0/12 Chrys
38% brn-orng, thin, sporatic, powdery dense stain, Goe?
7/12 Goe
2% pI gn-blu, thin, powdery-xtln, Clay+/- Chrys?
2/12 Clay
3/12 None
124/610-612
Yqm
65% It blu, powdery, quite extensive, Cu-cIay?
3/12 Chrys
20% tour-blu, xtln, Chrys?
0/12 Goe
10% gn-gy, xtln, appears coeval w/ above, ChI-clay?
8/12 Clay
5% blk, patchy, xtln, Ten?, Neo?
1/12 None
660-662
Core too broken up
124/666-668
Tgdp
60% orng-brn, stain, looks like rust, Goe+/- Hem?
0/15 Chrys
40% maroon, stain, Hem?
8/15 Goe
0/12 Clay
Very difficult to get a good sample
7/15 None
124171 0-712 Tgdp/Yqm 39% brn, thin, powdery-dense stain, Goe?
0/18 Chrys
55% maroon-brn, dense thin coating/stain, Hem?
14/18 Goe
2% crm-gn-gy, v. fine powder, Clay+Cu?
1/18 Clay
4% It gn-blu, thin platy-powdery, Cu-cIay +/- Chrys?
3/18 None
Very difficult to get a good sample
124/760-762 YqrnlTgd 60% pI seafoam gn, thin, powdery, Cu-cIay?
0/16 Chrys
2% blk, smeared thin coating, Ten? or Neo?
4/16 Goe
8/16 Clay
19% maroon-brn, thin stain, Hem +/- Goe?
4/16 None
19% brn-orng, thin stain, Goe?
124/810-812
0/18 Chrys
Yqm
60% orng-brn, powdery-stain, Goe?
35% maroon-brn, thin stain, Hem + Goe?
11/18 Goe
2/18 Clay
5% pI blu-gn, powdery, thin, Cu-cIay?
5/18 None
Core missing and broken - but still representative
1/14
3/12
2/16
3/12
11/12
0/15
1/18
8/16
2/18
83
Drill hole 124-mf, cont.: Sample descriptions, based on visual inspection.
I
ample Numbe Lithology % Phases Present and Observations
124//l6U-/l62
1 gop
Itlu'}'o maroon-orn, tnm, oense, stam, Hem.
24% orng-brn, thin, powdery-stain, Hem+I-Goe?
2% crm-wht, thin powdery coating, Clay?
4% yl-gn, thin platy powdery coating, Clay+I-Cu?
10% It blu, platy,Clay+I-Chrys?
910-912
Core looked "out of place" - rounded, etc ...
124/912-914
Tgdp
5% rd-brn, platy coating, Hem+I-Goe?
10% maroon-brn, thin stain, Hem?
60% pi seafoam gn, powdery, platy, Cu-e1ay+I-Chrys?
18% It blu-gn, thin, powdery, Cu-e1ay?
5% tour-blu, xtln, dense, platy, Chrys?
2% firey orng, powdery stain, Goe?
124/960-962
Tgdp 60% pi gn-gy, powdery, thin, Clay?
20% e1r-wht, platy dense coating, Gyps?
20% maroon-rd-brn, thin sporatic stain, Goe+/-Hem?
124110 10-10 12
Tgdp
12411 060-1 062
Tgdp
12411110-1112
Tgdp
1160-1162
12411170-1172
(sulfide zone)
Tgdp
10% e1r, platy dense coating, Gyps?
20% maroon-brn, v. thin stain, Hem+l- Goe?
15% orng-brn, v. thin stain, Goe?
50% olive gn-gy, thick platy gouge wi slip surface,
interlayered in places wi orng-brn Clay+I-Gyps, Chl-e1a
5% apple gn, small blebs wi Gyps
10% deep rd-brn, thin powdery-stain, Hem?
50% maroon-brn, thin stain, Goe+/-Hem?
20% yl-brn (7J:3G), powdery-platy coating, Jar+I-Goe
20% e1r, dense platy coating, Gyps?
30% pi gn-gy, fine powdery coating, Clay+I-Cu?
15% rd-orng-brn, powdery-platy-stain, Goe+/-Hem?
55% brn-yl-orng, thin powdery coating-stain, Goe+/-Jar
May be mnr amnt of Gyps in all of the above
Core missing and broken
10% e1r, dense platy coating, Gyps?
30% rd-brn, thin platy stain, Goe+/-Hem?
20% crm-gy, platy, thin, Clay?
40% crm-wht, platy-powdery, coating, Clay?
12411210-1212 Tgdp/Yqrn 60% e1r, dense platy coating, v. thin, Gyps?
(sulfide zone)
30% It gn-gy, powdery coating, sparse, Clay+I-Cu?
10% orng-rd, thin stain, Goe+I-Hem?
Most fracs have v. little if any mineralization
ype 01 lJomman 10rall'racrure~1
racture Coatin oated wi Coppe
U/lj Lnrys
)/1J
5113 Goe
5/13 Clay
3/13 None
1112 Chrys
2112 Goe
7112 Clay
2112 None
8/12
0111 Chrys
3111 Goe
3111 Clay
2111 Gyps
3111 None
OliO Chyrs
4110 Goe
2110 Clay
3/10 Gyps
1110 None
3111
0/9 Chrys
419 Goe
0/9 Clay
2/9 Gyps
3/9 None
OliO Chyrs
6110 Goe
3110 Clay
OliO Gyps
1110 None
0/15 Chyrs
3115 Goe
8115 Clay
2/15 Gyps
2115 None
016 Chrys
1/6 Goe
1/6 Clay
1/6 Gyps
3/6 None
OliO
0/9
3/10
0115
1/6
84
APPENDIX B: XRD Results by Drill Hole.
Mineral phases identified by x-ray diffraction in drill hole 68-mf as a function of
downhole depth and bench level.
-a
-
c
Qj
CI.I
~
..c
u
c:
CI.I
~
..c
CI.I
"0
..c
c:
~
8
CI.I
~
>
~
MP
383-385
1105-1055
433-435
1055-1 005
PP
MP
483-485
1005-955
PP
PP
533-535
955-905
MP
583-585
905-855
MP MP
633-635
855-805
683-685
805-755
PP
MP
733-735
755-705
783-785
705-655
MP PP
833-835
655-605
MP MP
883-885
605-555
933-935
555-505
P
PP PP PP
983-985
505-455
PP PP PP
1033-1 035
455-405
See text for discussion.
PP
MP
P
P P
PP
PP
PP
P
PP
P
MP
P
PP
PP
PP
PP
MP P
MP
P
PP
P
P
PP
MP
PP
P
MP
PP
P
P
PP
P
P = Present
PP = Probably Present
MP = Maybe Present
MP
PP
MP
P
PP PP
P
P
P P
P
P
P
P
P P
P
P P
P P
P
P
P
PP PP
PP
85
Mineral phases identified by x-ray diffraction in drill hole I 08-mf as a function of
downhole depth and bench level.
~
~
:::i
- -
.c
Co
CII
C
CII
UJ
«
CII
~
Qj
>
(5
.c
CII
...J
I:
.c
(,)
8==
-~
I:
373-375
1105-1055
MP
423-425
1055-1005
PP
473-475
1005-955
MP
543-545
955-905
P
573-575
905-855
623-625
855-805
673-675
805-755
723-725
755-705
773-775
705-655
828-830
655-605
PP
873-875
605-555
P
923-925
555-505
P
973-975
505-455
P
P
P
PP
P
P
PP
P
P
P = Present
PP = Probably Present
MP = Maybe Present
See text for discussion.
P
P
P
PP
P
P
PP
PP
PP
P
P PP
P
P
P
P
P
P
PP
PP
PP
P
P
P
P
P
P
P
P
P
PP
PP
P
P
PP
P P
P P
P
PP
MP
P
P
P P
P P
P
P
PP
PP
PP
P
PP PP PP
P
MP
MP PP
P
P
P
P
P
P
P
P
P
P
P
86
Mineral phases identified by x-ray diffraction in drill hole 124-mf as a function of
downhole depth and bench level.
CII
~
Qj
>
CII
...J
.c
(,)
c:
&l
360-362
1105-1055
P
410-412
1055-1005
MP PP
460-462
1005-955
P
P
510-512
955-905
PP
565-567
905-855
P
610-612
855-805
666-668
805-755
710-712
755-705
760-762
705-655
P
810-812
655-605
PP PP
860-862
605-555
PP
P
P
PP
P
PP
P
555-505
P
P
960-962
505-455
PP
P
PP
P PP
PP
P
P
P
P
PP
PP
PP
P
PP
P
MP PP
P
P
P
P
MP
PP
P
P
P
P
PP
P
P
P
P
P
P
P
P
P
MP
P
P
PP
P
P
P
P P
PP
PP
P
PP
P
PP
912-914
P
P
P
MP
P
MP
1010-1012
455-405
PP
P
P
P
P
1060-1062
405-355
PP
PP
P
P
P
1110-1112355-305
PP
MP PP PP
1170-1172
305-255
PP
P
P
1210-1212
255-205
PP PP
P = Present
PP = Probably Present
MP = Maybe Present
See text for discussion.
PP
PP
P
P
P
MP PP
P
P
P
87
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