EPS 109 2011 Field Guide
Northeastern Pennsylvania and Northern New Jersey
April 27-29, 2011
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Table of Contents
Day 1:
Page
Regional Tectonics of the central Appalachians . . . . . . . . . . . . . . . . . . . . . 3
Stop 1.1: Marcellus Shale Gas Drilling Site, Towanda, PA . . . . . . . . . . 5
Geology of the Marcellus Shale ……………………………………………................ 5
Geophysical Well Log Data …………………………………………………………… 12
Gas drilling information for the Marcellus Shale………………………….................. 6
Stop 1.2: Lackawanna Underground Coal Mine, Scranton, PA . . . . . . 14
Geology of the Anthracite Coal Fields…………………………………………………. 14
History of Coal Mining in Northeastern PA…………………………………………… 20
History of the Lackawanna/Continental Mine………………………………………… 21
Subsurface Mining Practices…………………………………………………………… 22
Stop 1.3: Old Forge Acid Mine Drainage Site, Old Forge, PA . . . . . . . 23
Day 2:
Stop 2.1: Stockton Surface Anthracite Mine, Hazleton, PA . . . . . . . . . 25
Geology of the Stockton Mine…………………………………………………………. 25
Coal Production at the Stockton Mine…………………………………………………. 26
Stop 2.2: Franklin Zinc Mine, Franklin, NJ . . . . . . . . . . . . . . . . . . . . . . 27
Geologic Setting…………………………………………………………………………. 27
Fluorescent minerals ……………………………………….………………………….. 30
Minerals to look for at the Buckwheat Dump…………………………………………. 30
History of Mining in the Franklin Mining District………………………………………. 32
List of Minerals found in the Franklin Mining District………………………………… 33
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Geologic Map of Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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2
Regional Geology of the Central Appalachians
The Appalachian mountain belt and adjacent areas of the North American continent have
experienced a long and complex geologic history. The first major tectonic event, the
Grenville Orogeny, caused extensive regional folding, faulting, volcanism, and
metamorphism 1.35-1.03 billion years ago. This period of metamorphism produced the
metal deposits that we will visit on the last stop of the trip. These ancient rocks also
represent the crystalline basement that underlies the younger carbon-bearing rocks that we
will see on the first stops of the trip.
During the Cambrian (540-500 million years ago), the proto-North American continent rifted
apart and an ocean basin (the Iapetus Ocean) formed to the east, creating a passive
margin much like the one we have today (Figure 1, a and b). During this time, thick
sequences of carbonate rocks were deposited on top of the crystalline basement
sequence.Due to a shift in plate motions during the Ordovician (480-440 million years ago),
subduction of part of the oceanic crust underlying the Iapetus Ocean initiated, forming a
volcanic island arc called the Taconic arc (c). As the entirety of the oceanic crust
subducted, the volcanic arc collided with the North American continent (called Laurentia),
which caused a mountain-building event called the Taconic orogeny (d). This mountainbuilding event, like the others described here, caused folding and faulting of the rocks
involved, which can be seen as we travel west through upstate New York. Mountainbuilding also causes metamorphism, or alteration and transformation of the minerals, as the
rocks are buried and subject to high pressures and temperatures.
Subduction of the oceanic crust on the other side of the now accreted Taconic arc began in
the late Ordivician (d). By the middle Silurian (440-420 mya), the Iapetus ocean was
closing as the oceanic crust was subducting beneath the North American continent and
ancient microcontinent called Avalonia to the east (e). As the Iapetus ocean closed, the
Avalonian microcontinent collided with the North American plate, resulting in a second
mountain-building event called the Acadian Orogeny (f). This collision occurred from 375325 million years ago. The Avalonian microplate was then sutured onto the North
American continent, and its remnants form the crust that underlies most of eastern
Massachusetts.
Both the Taconic and Acadian mountain building events caused the formation of ocean
basins west of the mountain ranges. Sedimentary units deposited in these basins contain
both the hydrocarbon and coal bearing units that we will examine on this trip.
By about 300 million years ago, continued closure of ocean basins to the east of the North
American continent caused the collision of North America and Africa (or Gondwana) to form
the super-continent Pangaea. The continent-continent collision of the Alleghenian Orogeny
created a massive mountain belt, on par with the current Himalayans. Pangaea began to
break up around 220 million year ago. As the continent rifted apart, oceanic crust began to
form as the proto-Atlantic Ocean began to widen.
3
Figure A. a-f correlate to information presented in the text. From Suppe, 1984.
This series of tectonic events led to the arrangement of rock units seen regionally, as
illustrated in the map on page 1.
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Stop 1.1: Marcellus Shale Gas Production
Geology of the Marcellus Shale
The Marcellus shale is a black, organic-rich shale of middle Devonian age that extends
throughout portions of southern New York, Pennsylvania, eastern Ohio, West Virginia, and
small areas of western Maryland, eastern Kentucky, northeastern Tennessee, and western
Virginia. Throughout most of its extent, the Marcellus formation is nearly a mile or more
below the earth’s surface. It is between 0 and 100 feet thick through most of its extent
(Figure 1.1.1).
Figure 1.1.1a. Depth of the base of the Marcellus Shale (Milici and Sweezey, 2006).
5
Figure 1.1.1b. Thickness (right) of the Marcellus Shale (Milici and Sweezey, 2006).
Depositional Environment
During the Middle Devonian period (380-390 MYA), the Avalonian microplate collided with
North America as the intervening oceanic crust was subducted. This caused a
mountainbelt to form southeast of this area and roughly parallel to the current eastern coast
of North America in an event known as the Acadian Orogeny. The load of the thick
continental crust in the mountainbelt caused an associated downward flexure of the crust in
front of the developing mountain belt called a foreland basin (Figure 1.1.3). The Marcellus,
and other black shales in the region, were generally deposited atop unconformities during
periods of sea-level rise. These “trangressions” coincided with periods of high global
temperatures and organic productivity. For the Marcellus, the bottom and western side of
this basin were anoxic, sediment-starved environments with restricted circulation, leading to
the deposition and preservation of organic materials (Figure 1.1.4). The organic matter
consisted of marine planktonic organisms, which becomes Type II and III kerogens.
Because deposition began in the southeast and moved to the northwest over time, the
Marcellus shale is thickest in the southeast (Figure 1.1.1a). However, the rocks in the
southwest were deposited with the least clastic input from the erosion of the growing
mountainbelt to the southeast, and thus have higher total organic carbon (TOC) values (up
to 11-12% TOC, Figure 1.1.5). The best shale gas plays are located in areas where the
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TOC’s are high, and the units relatively thick. Moreover, the shale needs to be buried
sufficiently to have reached the gas window and retained the gas in the formation (Figure
1.1.6). For these reasons, the Marcellus in south-central New York and northeastern
Pennsylvania has drawn considerable interest and has been the location of the most
intense Marcellus shale gas development (Figure 1.1.8).
Figure 1.1.2. Devonian Stratigraphy of the Catskill Region of New York (from Smith and Leone).
While the Marcellus is primarily black shale, it is interbedded with minor limestone beds that
were the result of sea level variations during deposition. Additionally, the original sulfur
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content of the organic matter has led to the occurrence of pyrite throughout the unit,
especially near the base.
Figure 1.1.3. Schematic cross-section of depositional setting of Marcellus Formation (from Smith and Leone).
.
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Figure 1.1.4. Tectonic Setting of Marcellus Shale deposition, Early Devonian Period (previous page). Largescale tectonic recontstruction and stratigraphic column (top). The location of the inset on this page is marked
by the red box.
Figure 1.1.5. Net feet of organic-rich shale in the Marcellus Formation, after Piotrowski and Harper, 1979.
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Figure 1.1.6. Thermal maturity determined from vitrinite reflectance (%Ro) of the Marcellus Shale in New
York. Areas to the west of 1.1 are thermally immature, 1.1-~2 are in the oil generation window, and areas east
of 2 are in the gas generation window.
Geophysical Well Log Data for the Marcellus Shale
Because of their relatively high content of mineral fragments that host radioactive elements,
shales tend to have a characteristically high gamma ray signature (Figure 1.1.7). The
Marcellus has long been recognized in drilling as a zone of high gamma ray, or GR, values.
It is clear by examining the correlation between gamma ray, density (RHOB) and total
organic carbon (TOC) that the shale layers are distinctively radioactive, dense, and have a
high TOC. TOC percentages reach over 16% in some of the lower reaches of the log. The
upwards decreasing TOC within the Marcellus Formation likely represents the larger input
of clastic material from the east in later sequences. Finally, the calcite rich layers are
anticorrelated with the other logs, indicating the presence of limestone layers.
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Figure 1.1.7. Geophysical data from a borehole in the Marcellus Shale, showing Gamma Ray (GR), Calcite,
density (RHOB), and total organic carbon (TOC).
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Shale Gas Production and Development
Since the 1930’s, it has been recognized that the Marcellus shale contained significant
accumulations of natural gas, as drillers encountered a gas “kick” when drilling through this
unit to reach a deeper reservoir rock. However, due to the low porosity and permeability of
the shale, it was not deemed an economically-viable accumulation.
Two major recent advances in drilling technology have made exploitation of this resource
possible: hydrofracture and deviated wells. Hydrofracture, or hydrofracking, is the process
of injecting large quantities of fluids and sand into the borehole at high pressure—when the
pressures exceed the lithostatic strength of the rock, they induce fracturing. These
fractures link natural fractures and create new ones, increasing the permeability of the rock
layer, which allows subsequent flow of natural gas to the borehole. Deviated wells allow
developers to drill wells that deviate from vertical, and even run horizontally. This allows for
the drilling of a horizontal borehole that can stay within the shale unit for horizontal
distances of over 1 km; this increases the surface area of the borehole in contact with
fractures in the shale, also increasing gas production.
Gas production from the Marcellus Shale in Pennsylvania
The first modern well for Marcellus gas was drilled by Range Resources in 2003 in
southwestern PA. Recent studies (Engelder and Lash, 2008) estimate that the Marcellus
shale may contain 500 TCF of natural gas; if 10% of that was developed, it would supply
US energy needs for 2 years and be worth $1 trillion at the wellhead. The Marcellus shares
many characteristics with other shale gas plays in the US, but is distinguished by its greater
size and resource base (Table 1).
Table 1. Information on major shale gas plays in the US. Arthur et al., (2008).
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Given the promise of the accumulation of resource, the rate of production from the
Marcellus has increased dramatically in the last several years, as illustrated in Table 2
below. Many of these wells produces more than a million cubic feet of gas per day in their
first year of production, but rates are expected to decline.
2007
2008
2009
2010
27
161
785
1386
Table 2. Marcellus shale wells drilled in PA per calendar year (PA DEP).
Figure 1.1.8 Top: Producing wells in Pennsylvania, non-Marcellus in blue, Marcellus in red. Bottom: New
wells drilled in 2011 (as of 04/06/2011).
The PA DEP is responsible for reviewing and issuing drilling permits, conducting
inspections of drilling operations, and responding to water quality problems. It derives its
legal obligation to these activities from numerous state laws, including the Clean Streams
Law, Solid Waste Management Act, Water Resources Planning Act, and the Worker and
Community Right to Know Act.
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Stop 2.1: Underground Anthracite Coal Mine Tour
Figure 1.2.1. Geologic Map of the Scranton Area.
Geology of anthracite coal in NE Pennsylvania
Anthracite is present in 4 major coal
coalfields in eastern Pennsylvania,
commonly referred to as the Northern,
Eastern Middle, Western Middle, and
Southern Anthracite Fields (as seen in
Figure 2.1.2, at right). Our first stop, at
the Lackawanna Coal Mine near
Scranton, PA, is in the Northern Field.
Each of these fields consists of an
exposure of Carboniferous-age coalbearing strata in a broad synclinal
structure.
Figure 1.2.2. Anthracite Coal Fields of Eastern
Pennsylvania. Location of figure 2.1.1 in red.
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Stratigraphy
The anthracite stratigraphy in northeastern Pennsylvania consists of four main formations
that we will see at sites 1.2 and 2.1. In order from oldest to youngest, the Pocono, Mauch
Chunk, Pottsville, and Llewellyn Formations. These rocks are Carboniferous in age (359318 million years old), which makes them just slightly younger than the Devonian-aged
Marcellus Shale that we discussed at stop 1.1.
Pocono Formation
The Pocono Formation consists mainly of light to medium gray sandstone, pebbly
sandstone, and conglomerate. It is mid-Mississipian in age (345-350 MYO). It is 300-400
meters in thickness. The lower unites consist of light to medium gray sandstones and
conglomerates, with minor amounts of siltstone. The upper unit consists of more coarselygrained gray conglomerates. In various parts of the region, it is commonly mapped by its
subunits, the Spechty Kopf (lower), Beckville (middle) and Mount Carbon (upper) members.
Because the sandstones and conglomerates of the Pocono formation are very resistant to
weathering, they are commonly the ridge-formers in the valley and ridge portion of the
Appalachians.
Mauch Chunk Formation
The Mauch Chunk Formation is a red bed. It is approximately 2000 meters thick in the
south, but thins to the north and is locally not present in the North Field. The lower portion
consists of gray conglomerates interbedded with red sandstones, silstones, and shales.
The middle and upper members consist of grayish red conglomerates interbedded red
sandstones, siltsones, and shales. It is late Mississippian in age (320-345 MYO).
Pottsville Formation
The Pottsville Formation is a gray-colored, white-quartz-pebble conglomerate of early
Pennsylvanian Age (318-306 MYO). It is also composed of some gray sandstone and
siltstone layers, and is approximately 500 m thick, although it is thinner in the northern
portion of the region. The upper portion of the Pottsville formation consists of finer grained,
but more angular conglomerates, and has local, thin shale coal beds. Like the Pocono
formation, the conglomerates and sandstones of the Pottsville formation are very resistant
to weathering, and as such, this formation is a common ridge-former in the region.
Llewellyn Formation
The Llewellyn Formation is the major anthracite-bearing formation of the eastern
Pennsylvania coal fields. It is mid to late Pennsylvanian (308-300 MYO). The base of the
formation is the underclay/shale of the Buck Mountain coal bed. It is approximately 1100 m
thick. Forty beds of anthracite were identified as stratigraphically continuous and
economically important within this formation (Wood et al, 1969), varying in thickness from
0.5 meters to 15 meters (the Mammoth layer). Layers of shale, siltstone, sandstone, and
conglomeratic lenses separate the black or dark gray coal layers in regular sequences.
Over 100 species of plant fossils have been identified in the Llewellyn Formation. This rock
unit is easily eroded and forms the valleys in the region.
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Figure 1.2.3. Stratigraphy of the Pennsylvania Anthracite Fields.
Geologic setting
Throughout the Mississippian and Pennsylvanian, the continental margin of the North
American continent was approximately parallel to the current continental shoreline.
Between 375 and 325 MYA, the Acadian Orogeny occurred due to the collision of the
Avalonian microplate with North America. As a result of this mountain-building event, a belt
of mountainous highlands existed to the Southeast of this region, and elevation decreased
into the foreland basin to the northwest (at this location). As these mountains were eroded,
coarse sediments shed off of them and were carried by high-energy braided streams to be
deposited in this region as the conglomerates of the Pocono formation.
After the Acadian Orogeny ceased, subduction continued to close the ocean dividing the
North American and African Continents. This region continued to receive sediments
sourced from the highlands to the southeast, but the sediments in this region began to
represent the lower reaches of ephemeral stream channels. As these sediments were
exposed to the atmosphere in an arid environment while they were being deposited, the
iron found in them is in the oxidized state, resulting in “red beds.” These layers represent
the Mauch Chunk Formation.
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As the African continent approached the North American continent, the region began to
have renewed mountain building in what is known as the Alleghenian Orogeny, beginning
around 310 MYA. Additionally, the climate became much more temperate (less arid), and
the alluvial plain supported the growth of dense forests with incredibly high organic
productivity. Meandering stream channels and changing sea level led to the flooding of
these coastal forests, leading to the preservation of the organic material as peat, which was
subsequently buried by overlying sediments and became the precursor to the anthracite
coal.
Figure 2.1.4. Depositional setting of Carboniferous-aged rocks in Pennsylvania.
Anthracite Coal Formation
As the African Continent collided with North America 300-220 MYA, thick clastic
sedimentary units were deposited on top of the Llewellyn formation, and thrust faults
uplifted older rock layers over these units, burying them deeply in the earth. As the peat
layers were buried more deeply, they underwent thermal diagenesis.
During the process of burial and diagenesis, the much of the oxygen and hydrogen were
driven out of the coal. The anthracite coal in the region now consists of up to 94% C, 3%
O, and 3% H, and has a heating value of 13,600 Btu per pound of coal. Based on vitrinite
reflectance and metamorphic mineral assemblages in the adjacent shales, the anthracites
reached temperatures of 200C in the west, and 260-270C in the southeast. Depending
on the geothermal gradient, this correlates with a burial depth of 5-9 km. Subsequent uplift
and erosion of the overlying layers have exposed these rock layers at the surface.
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Figure 1.2.5. Anthracite Coal.
The anthracite coal of this region has the
appearance of a “bright banded” coal. Most of the
coal is very “bright,” meaning that it has a high
luster. The bright coal is >80% vitrinite, or wellpreserved woody material. Intervening dull bands
are composed of degraded woody material, and
other minerals, mostly kaolinite clay and silt-sized
mineral clasts.
Figure 1.2.6. Vitronite reflectance (Rmax) of anthracite coals in eastern Pennsylvania (from Hower et al,
1993).
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Tectonics of the Mississippian and Pennsylvanian
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History of coal mining in NE Pennsylvania
Coal production from eastern Pennsylvania helped to fuel the industrial growth and
domestic heating needs of the northeastern United States from the mid 19 th through mid
20th centuries.
Anthracite coal was first reported in Pennsylvania on a map prepared in 1752 by John
Jenkins, Sr., and was first used by the Gore Brothers in their blacksmith shop in WilkesBarre in 1769. Coal mining in the anthracite fields began in earnest in early 1800’s, and
accelerated rapidly after the Civil War. In conjunction with the bituminous coals of Western
Pennsylvania, coal mining fueled the iron, steel, chemical, glass, and metal-fabricating
industries that flourished in Pennsylvania. Production of anthracite coal in Pennsylvania
peaked in 1918 at nearly 100 Mt/yr, with nearly half of that production coming from the
North Field, where we will be spending the remainder of the day. Rates of anthracite
production have declined dramatically since their peak in the early 20th century, and the
primary method of anthracite mining switched from subsurface to surface mining and
reworking mine waste in the 1961.
Figure 1.2.7. Anthracite production from 1890-1995 in Pennsylvania.
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History and geology of the Lackawanna Mine
Mining at the
Lackawanna Mine began in
1860 and ceased in November
of 1966. This mine was part of
a series of mines owned and
operated by the DL&W Coal
Company, and later Moffatt
Coal, in the area; this shaft sat
on the site of the Continental
Colliery (which burnt down in
1919 and was never rebuilt)
and shared its name. The No.
190 slope was opened in
1959—it was actually driven
from the bottom up to the
surface, as it was becoming
too expensive to haul coal out
of this portion of the mine from
Figure 2.1.10. A portion of the Continental 190 slope prior to
the nearby Moffat shaft. The
restoration (www.undergroundminers.com)
coal that was produced from
this mine was shipped about 3 miles to the Taylor Colliery in Old Forge (near the next
stop), where it was processed.
At its largest extent, the Continental mine consisted of a 528 foot deep shaft with four levels
extending over 2 miles outward in the Lackawanna valley. The mine system intersected 6
individual coal seams within the Llewellyn Formation. At the center of the valley, the coal
seams are so thick, and nearly flat, that room-and-pillar mining was practiced (this portion
of the mine is now flooded). In 1904, the mine employed 457 miners, and produced
246,561 tons of coal; even as late as 1964, the mine produced 51,872 tons of coal.
Much of the mine was flooded when the mine was abandoned and the pumps were
shut off; of the original four levels, only the highest one remains unflooded. It reopened in
1985 as an educational and mining heritage site.
We will descend down the old Continental No. 190 slope at a 25-degree slope in a
mine car to the foot of the shaft, at 300 feet below the land surface. During our hour-long
underground tour, we will see the Clark Vein, Dunmore #1, and Dunmore #2 veins of the
Llewellyn Formation. We will also learn about the logistics and challenges of underground
mining, including transportation, ventilation, timbering and structural support, fires, and
working conditions.
Mining in the anthracite regions was an exceptionally hazardous occupation; for
example, in the year 1885, there were 72 fatalities (one of which was at the Continental
Mine) in the anthracite mining districts of PA. More than 62% of the deaths were due to
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falling of roof rocks and coal-related. The next leading cause of death was explosions of
powder and blasts, at 11%, although this hazard represented the single largest source of
multiple-fatality accidents in coal mines historically in the Anthracite region.
Subsurface Anthracite mining practices
Because the rock units in eastern Pennsylvania have been folded and faulted during the
Alleghenian mountainbuilding event (figure, below), they are folded and faulted at a
regional scale. As these layers are dipping, sometimes very steeply, due to this tectonic
activity, traditional room-and-pillar subsurface mining processes are most often ineffective,
so other methods were used.
Generally, subsurface anthracite coal mining was done by the breast-and-pillar method,
which consists of the following steps (figure, on the next page):
1. Miners enter by a tunnel, slope, or shaft,
2. Two horizontal headings are driven parallel to the strike of the coal bed from the
shaft,
3. The upper heading, or “monkey” provides access to drill and blast upward in the
coal bed dip for distances of 2-300 feet (“breast” development),
4. Coal falls by gravity into coal cars in the lower heading, or “gangway,”
5. Coal is hauled out through the gangway. (from Eggleston et al 1999, and
illustrated in the figure on the next page)
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Stop 2.3: Old Forge Borehole Site
History of the Old Forge Borehole
Acid mine drainage affects more than 2400 miles of streams and rivers in the state of
Pennsylvania, primarily as a result of historical and abandoned coal mining practices. A
USGS study of the largest AMD discharges in the anthracite region indicates that the
discharge water from many mines a pH below 6.0, and i elevated concentrations of
aluminum, calcium, cobalt, iron, lithium, magnesium, manganese, nickel, strontium, zinc,
and sulfates.
The Old Forge borehole was drilled by the Army Corps of Engineers in 1961 to alleviate the
flow of the water into the basements of the homes in low-lying areas throughout the
Lackawanna Valley. The borehole is over 400 feet deep and 3.5 feet in diameter, and
drains from 8 to 10 million gallons of AMD per day. The outflow drains directly into the
Lackawanna River, which subsequently flows into the Susquehanna River 3 miles
downstream. It is the largest single source of AMD in the Chesapeake basin drainage area.
Water geochemistry over time
When subsurface coal mines are in operation, they must be actively pumped to depress the
water table to below the level of the mine. Now exposed to oxidizing conditions, the pyrite
(FeS2)-bearing coal seams are oxidized to create weathering products (Equation 1). When
the mine is abandoned, the pumps no longer function to keep the mine dry, and the water
able rebounds. The H+ ions produced by this process serve to lower the pH of the waters
23
in the mine; as a result, Iron and other metals are soluble in the water, which flows out of
the mine into the ground and surface water systems.
When the low pH waters come into contact with more neutral pH surface waters, yellowboy,
or Fe(OH)3 is precipitated into streams (Equation 2). We will see extensive deposits of
yellowboy at the Old Forge Borehole that was deposited by this process.
At the Old Forge Borehole, the primary current pollutant is iron (6.1 mg/l <1.5 mg/l water
quality standard). The outflow
also exceeds water quality
standards for aluminum during
storm flows (as of September,
2010). Although these levels
are still considerably higher
than standards, they have
substantially improved over the
past 50 years (figure, below).
In spite of this improvement, the
portion of the Lackawanna
River downstream of the Old
Forge borehole is nearly devoid
of acquatic life.
A number of mineralogical,
hydrological, and mine-related
factors influence the
composition and severity of
AMD. However, in nearly all
cases, AMD in the anthracite
fields has been observed to
have improved on the decadal
timescale, possibly due to
changes in the exposed surface
area of susceptible minerals
and possible coating of sulfide
minerals.
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Stop 2.1: Stockton Surface Anthracite Mine, Hazleton, PA
Geology of the Stockton Mine
The Stockton mine, owned by Atlantic Coal, is a 900 acre region in the eastern portion of
the Hazleton Coal basin, in the Eastern Middle Anthracite coalfield. The Stockton coal field
consists of a long, narrow synclinal fold striking east-northeast/ west-southwest, and
plunging toward the west. Three coal seams within the Llewellyn Formation are present in
the field: the primary target is the Mammoth Seam, which is the thickest, and most
historically productive seam in the anthracite coal district. It is approximately 30 feet thick
at this location. Other minor seams present here are the Primrose seam, which lies above
the Mammoth, and is 5-6 feet thick, and the Wharton Seam, which, though 7-8 feet thick, is
not targeted currently because it lies 60-70 feet below the Mammoth Seam, and the
resulting overburden is too thick for its mining to be economic.
Stockton has a proven reserve of 4.2 million tons of run-of-mine coal, or 2.1 Mt of washed
anthracite and a projected mine lifetime of 10 years. Atlantic Coal believes that by
extending exploration of the current deposit to depth, or broadening interests laterally, that
there are an additional 10 Mt of resource within a 10 mile radius, and 300 Mt. within a 30
mile radius, of the active Stockton mine.
Figure 2.1.1. Geologic map of the Hazleton Area.
25
Coal Production at the Stockton Mine
The region where the Stockton mine is location was extensively mined in the subsurface
from the mid-19th to mid-20th centuries.1 However, the process of subsurface mining often
leaves more than 50% of the coal in place in order to support the structural integrity of the
mine. This remaining coal is now what is mined at the Stockton Mine using surface
methods that are now possible due to the technological advancement of heavy machinery.
Mining is primarily accomplished by 21-yard bucket hydraulic excavators and The coal is
processed on site at the Stockton Colliery, where the mined material is combined with
water and the coal is separated by density from waste rock. It is then milled to different
sized pieces, based on its end use.
In the first quarterly report of 2011, the Stockton mine produced 120,850 tons of ROM coal
and 503,677 m3 (bank) of overburden removed during the quarter (International Mining
Magazine, 4/18/2011). The coal here has a carbon content of 86-87%, and is very low in
volatile content. Because of its high carbon content and clean burning quality, the coal
from this mine is primarily used for steel production in the United States. Minor amounts
are also used in metallurgy, filtration and tincture for glass products.
Reclamation strategies
The ratio of overburden to coal, or stripping ratio, at the Stockton mine fluctuates, but
recent work has been at 11:1 to 12:1. This overburden is removed to expose the coal
seam, and then taken to a disposal area in a previously mined section of the mine. The
concurrent backfilling process, which is required by Pennsylvania Law, ensures that
reclamation is done concu rrent with development, and that the open pit area remains
within permitted limits. The backfilled areas are restored approximately to their original
contour and are reseeded with grass and tree seedlings.
1
The underground portion of the Stockton Mine is most noted for a mine disaster that occurred on December 20,
1869, when subsurface mining too close to the land surface (within 20 feet) caused catastrophic land subsidence
and engulfed two homes, killing 12 people (New York Times, Dec. 20-22, 1869)
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Stop 2.2: Franklin Zinc Mine
The Franklin / Sterling Hill Mineral District is a world-class and –renown mineral site. 357
different mineral species have been identified at Franklin Hill—this represents
approximately 10% of all described mineral species in the world. 69 different minerals were
first described here. Additionally, about 10% of the minerals found in this mineral district
are found nowhere else on earth. It is also known as the “fluorescent mineral capital of the
world,” as several of the minerals found here are strongly fluorescent under exposure to
long- and short-wavelength ultraviolet light.
Regional Geologic Setting
As we have traveled East, we have encountered increasingly old rocks; the rocks in the
Franklin Mineral District are all Precambrian and Cambrian in age (>500 MYO). These
rocks, now metamorphic rocks such as gneisses and marbles, were originally deposited as
sedimentary and volcanic layers and were subsequently metamorphosed by burial and
deformation related to tectonic mountain-building events.
The oldest rock units are Precambrian. They were originally deposited as sedimentary and
volcanic layers in a rift environment prior to the Grenville Orogeny. At this location volcanic
and sedimentary rocks were overlain thick limestone layer, then another volcanic unit, then
another limestone layer, then another volcanic unit.
During the Precambrian, these rocks were subject to a long period of intense folding,
faulting, and deformation associated with the Grenville Orogeny. These rocks were
metamorphosed to sillimanite grade (650-800 C, 4-10 kbar of pressure, ~30 km burial
depth). Under these intense metamorphic conditions, the rocks completely recrystallized;
the volcanic and clastic sedimentary rocks metamorphosed to gneiss, while the limestones
metamorphosed to marble. The age estimates for the burial and metamorphism vary from
1150 MY to as early as 950 MY.
Gneiss
Marble
The zinc ore body occurs in lenses within the Franklin Marble. The conditions that led to
the formation of these highly unique mineral assemblages remains the source of much
uncertainty and debate. It has been hypothesized that much of the metal content of the
proto-ore was in place prior to metamorphism, as a Zn-Fe-Mn rich dolomite lens. Under
the high-grade metamorphic conditions that altered the surrounding limestones to marbles,
the elements and minerals in the dolomites recrystallized into the phases seen today. A
27
hydrothermal alteration mechanism has also been proposed by some authors. Soon after
ore formation of a few pegmatites intruded into the existing rocks and are dated at 965 MY.
Subsequently, the rocks were uplifted and cooled. They were exposed at the surface from
600-500 MYA, during which time they were extensively eroded and weathered. Then, the
Hardyston quartzite was deposited unconformably on top of the Precambrian rocks,
followed by the Kttatinny Limestone/Dolomite in the Cambrian and Ordovician. The entire
area was folded, faulted, uplifted, and eroded to expose it once again during the Acadian
and Alleghenian Orogenies as well. The structure of the mineral district is most commonly
described as a northeast-trending, overturned isoclinal synform that plunges 10-30 to the
northeast.
Geologic Units (from Dunn, 1995)
Cambrian-Ordovician
Kittatinny formation - Blue limestone, mostly dolomitic, with locally shaly and sandy
areas. Thickness is 762-914 meters.
Lower Cambrian
Hardyston formation - Quartzite with locally conglomeratic domains. Thickness is about
9 meters locally.
Precambrian
Pochuck Gneiss series - Interlayered gneisses, predominantly microcline-, biotite-,
hornblende-, or pyroxene-rich, with local concentrations of graphite or garnet.
Thickness is over 610 meters.
Wildcat Marble - Coarsely crystalline marble, containing blocks of gneiss and pegmatite;
still unstudied. Thickness is 91 meters.
Cork Hill Gneiss - Very similar to the Pochuck Gneiss. Thickness is 244-305 meters.
Franklin Marble - Coarsely-crystalline marble, locally dolomitic and graphitic throughout.
Thickness is 335-457 meters.
Median Gneiss - Biotite gneiss. Thickness is 15-91 meters.
Franklin Marble - Description given above. Thickness unknown, may be over 152
meters.
Byram Gneiss - Similar to Pochuck Gneiss. Thickness over 610 meters.
28
Figure 2.2.1. Geologic map of the Franklin/Sterling Hill Mining District, from Palache (1935).
29
What makes minerals fluorescent?
Most pure minerals do not fluoresce; most require certain impurities, or activators, in
sufficient quantities to make them fluoresce. Different activators can make the same
mineral fluoresce in different colors. The most common fluorescent minerals that we will
find here are calcite and willemite. The calcite fluoresces red, orange, or pink due to lead
and manganese impurities. The willemite fluoresces bright yellowish-green due to traces of
manganese. Other fluorescent minerals
that we might see are hardystonite
(deep blue-violet fluorescence),
clinohedrite (orange fluorescence) and
esperite (yellow fluorescence).
Other minerals that fluoresce under UV
light that you might find at the
Buckwheat Dump include sphalerite
(brown adamantine, orange/pink/blue
fluorescence). In nearby Franklin
Marble, you may find diopside (dark
green pyroxene, fluoresces pale blue)
and norbergite (fluoresces yellow).
There are also impurities called
quenchers, which prevent fluorescence
despite the presence of activators.
Ferrous iron is the most notable
quencher.
Figure 2.2.2. Specimen from the Franklin Mine
in UV light, with calcite (red), willemite (green),
and hardystonite (blue/purple)
Minerals to look for at the Buckwheat Dump
The main zinc ores at the Franklin Hill mine have several minerals that are easy to identify
(especially since you identified them in lab). These minerals are common on the
Buckwheat dump, so look for them! In light of the spectacular variety of minerals found at
this location (listed at the end of this field guide for your amusement), you will likely find
some specimens that will be challenging to identify.
The zinc ore rocks commonly contain the following minerals: Franklinite (50%), Willemite
(32%), Calcite (13%), Zincite (1%), and other silicates.
30
Franklinite
Zincite
Franklinite (Zn, Fe, Mn)(Fe, Mn)2O4
Dark black, metallic, opaque crystals that often form in octahedrons. Slightly magnetic. No
cleavage (conchoidal fracture). Hardness of 6. Density 5.0-5.2 g/cm3. Reddish-brown
streak. Some samples have an iridescence like bornite.
Zincite ZnO
Submetallic, generally deep red, massive or granular crystals (rarely euhedral pyramidal
crystals). hardness of 4. Translucent, one cleavage, dense (5.4-5.7 g/cm3) yellowishorange streak. Non-fluorescent.
Willemite Zn2SiO4
Often light green to brown, translucent to opaque massive or granular crystals. If
crystalline, can be blocky prisms. Vitreous/resinous luster, white streak, density of 3.9-4.2
g/cm3, two poor cleavages. Fluoresces bright green in long and short-wave UV.
Calcite CaCO3
White or gray, mostly massive at this location, and coarse granular crystals.
Rhombohedral crystals are common, other shapes also occur. Colorless, white, orange or
gray, if Mn substitues for Ca, can be pink, surface alters to dull black. Calcite associated
with the ore rocks fluoresces strong orange-red in long- and short-wave UV, calcite from
the surrounding marble does not.
Willemite
Calcite
31
History of mining at the Franklin and Sterling Hill Mines
Mining of the similar nearby zinc deposit at Sterling Hill began in 1730, when the deposit
was explored, and soon abandoned, as a source of copper ore. The Sterling hill deposit
was later mined for iron ore (since franklinite is an iron-zinc oxide). This was a historically
very important source of iron ore in the early eastern United States. The naturallyoccurring manganese in the ore made the resulting processed iron tougher and less brittle,
making ores from this region highly desirable.
From 1848-1896, surface pits in the region
were mined for zinc ore by exploiting the
mineral hemimorphite (pictured at left).
Hemimorphite, a zinc silicate, was
deposited as a thick coating on rock
surfaces when the primary zinc ores were
exposed to long-lived weathering
processes. These deposits, though rich,
were only present locally, and were soon
fully exploited.
Dr. Samuel Fowler pioneered exploration
of the ore for zinc. A physician, who had a
keen interest in science and business, he acquired the mines in 1818 and 1824 with the
intent of developing a great commercial zinc industry in New Jersey. He succeeded in the
manufacture of zinc oxide, or zinc white, likely from zinc white, which was used as a
replacement for lead in white paint. Additionally, Dr. Fowler enlisted the help and interest
of many academic naturalists of the early 19th century. In fact, the earliest academic paper
in North America on the classification and description of a mineral was a paper on zincite
from this location. These deposits have been extensively studied by the scientific
community, and are the subject of over 1200 scientific publications.
Upon consolidation of the Sterling Hill and Franklin Hill mines under one entity, the New
Jersey Zinc Company, in 1897, the orebody was mined in earnest for the primary willemitefranklinite-zincite ore for zinc. The two mines produced over 33 Mt of zinc ore. Iron and
manganese were also coproduced from this ore. The Franklin mine closed in 1954 (and
Sterling Hill closed in 1986), and both mines are now open as educational and museum
sites.
Uses of Zinc
Zinc is valued for its anti-corrosive properties, and as such is commonly used as a coating
or alloy for other metals. Historically, zinc was used with copper to make brass and bronze.
Current applications of zinc include galvanizing steel and other metals (59%), diecasting
(16%), brass and bronze (10%), rolled zinc (6.5%), chemical/industrial processes (6.0%),
and other assorted uses.
32
Mineral species identified at the Franklin Hill Mine
A
Acanthite
Actinolite
Adamite
Adelite
Aegirine
Akrochordite
Albite
Allactite
Allanite-(Ce)
Alleghanyite
Almandine
Analcime
Anandite
Anatase
Andradite
Anglesite
Anhydrite
Annabergite
Anorthite
Anorthoclase
Antlerite
Apatite-(CaF)
[Fluorapatite]
Apophyllite-(KF)
[Fluorapophyllite]
Apophyllite-(KOH)
[Hydroxyapophyllite]
Aragonite
Arsenic
Arseniosiderite
Arsenopyrite
Atacamite
Augite
Aurichalcite
Aurorite
Austinite
Axinite-(Fe)
[Ferro-axinite]
Axinite-(Mn)
[Manganaxinite]
Azurite
B
Bakerite
Bannisterite
Bariopharmacosiderite
[Barium
Pharmacosiderite]
Barite
(IMA = baryte)
Barylite
Barysilite
Bassanite
Baumhauerite
Bementite
Berthierite
Bianchite
Biotite*
Birnessite
Bornite
Bostwickite
Brandtite
Breithauptite
Brochantite
Brookite
Brucite
Bultfonteinite
Bustamite
C
Cahnite
Calcite
Canavesite
Carrollite
Caryopilite
Celestine
Celsian
Cerussite
Chabazite-Ca
Chalcocite
Chalcophanite
Chalcopyrite
Chamosite
Charlesite
Chloritoid
Chlorophoenicite
Chondrodite
Chrysocolla
Chrysotile
[Clinochrysotile]
Cianciulliite
Clinochlore
Clinoclase
Clinohedrite
Clinohumite
Clinozoisite
Clintonite
Conichalcite
Connellite
Copper
Corundum
Covellite
Cryptomelane
Cummingtonite
Cuprite
Cuprostibite
Cuspidine
Cyanotrichite
D
Datolite
Descloizite
Devilline
Digenite
Diopside
Djurleite
Dolomite
Domeykite
Dravite
Duftite
Dundasite
Dypingite
E
Edenite
Epidote
Epidote-(Pb)
[Hancockite]
Epsomite
Erythrite
Esperite
Euchroite
Eveite
F
Fayalite
Feitknechtite
Ferrimolybdite
Ferro-actinolite
Flinkite
Fluckite
Fluoborite
Fluorite
Fluoro-edenite
Forsterite
Fraipontite
Franklinfurnaceite
Franklinite
Franklinphilite
Friedelite
G
Gageite
Gahnite
Galena
Ganomalite
Ganophyllite
Genthelvite
Gersdorffite-P213
Gerstmannite
Glaucochroite
Glaucodot
Goethite
Gold
Goldmanite
Graeserite
Graphite
Greenockite
Grossular
Groutite
Grunerite
Guérinite
Gypsum
H
Haidingerite
Halotrichite
Hardystonite
Hastingsite
Hauckite
Hausmannite
Hawleyite
Hedenbergite
Hedyphane
Hellandite-(Y)
Hematite
Hemimorphite
Hendricksite
Hercynite
Hetaerolite
Heulandite-Na
Hexahydrite
Hodgkinsonite
Holdenite
Hübnerite
Humite
Hydrohetaerolite
Hydrotalcite
Hydrozincite
I
Illite*
Ilmenite
J
Jacobsite
Jarosewichite
Jerrygibbsite
Johannsenite
Johnbaumite
Junitoite
K
Kaolinite
Kentrolite
Kittatinnyite
Kolicite
Köttigite
Kraisslite
Kutnohorite
L
Larsenite
Laumontite
Lawsonbauerite
Lead
Legrandite
Lennilenapeite
Leucophoenicite
Linarite
Liroconite
Lizardite
Löllingite
Loseyite
33
M
Magnesiohornblende
Magnesioriebeckite
Magnesio chlorophoeni
cite
[Magnesiumchlorophoenicite]
Magnetite
Magnussonite
Malachite
Manganberzeliite
Manganohörnesite
Manganhumite
Manganite
Manganocummingtonite
Manganosite
Marcasite
Margarite
Margarosanite
Marialite
Marsturite
Mcallisterite
Mcgovernite
Meionite
Meta-ankoleite
Metalodèvite
Metazeunerite
Microcline
Mimetite
Minehillite
Molybdenite
Monazite-(Ce)
Monohydrocalcite
Mooreite
Muscovite
N
Nasonite
Natrolite
Nelenite
Neotocite
Newberyite
Niahite
Nickeline
Nontronite
Norbergite
O
Ogdensburgite
Ojuelaite
Opal
Orthoclase
Orthoserpierite
Otavite
P
Parabrandtite
Paragonite
Pararammelsbergite
Pararealgar
Parasymplesite
Pargasite
Pectolite
Pennantite
Petedunnite
Pharmacolite
Pharmacosiderite
Phlogopite
Picropharmacolite
Piemontite
Powellite
Prehnite
Pumpellyite-(Mg)
Pyrite
Pyroaurite
Pyrobelonite
Pyrochroite
Pyrophanite
Pyrosmalite-(Mn)
[Manganpyrosmalite]
Pyroxferroite
Pyroxmangite
Pyrrhotite
Q
Quartz
R
Rammelsbergite
Realgar
Retzian-(La)
Retzian-(Nd)
Rhodochrosite
Rhodonite
Richterite
Roeblingite
Roméite
Rosasite
Rouaite
Roweite
Rutile
S
Safflorite
Samfowlerite
Sarkinite
Sauconite
Schallerite
Scheelite
Schorl
Sclarite
Scorodite
Seligmannite
Sepiolite
Serpierite
Siderite
Sillimannite
Silver
Sjögrenite
Skutterudite
Smithsonite
Sonolite
Spangolite
Spessartine
Sphalerite
Spinel
Starkeyite
Sterlinghillite
Stibnite
Stilbite-Ca
Stilbite-Na
Stilpnomelane
Strontianite
Sulfur
(IMA = sulphur)
Sussexite
Synadelphite
Synchysite-(Ce)
T
Talc
Tennantite
Tephroite
Tetrahedrite
Thomsonite-Ca
Thorite
Thortveitite
Thorutite
Tilasite
Titanite
Todorokite
Torreyite
Tremolite
Turneaureite
U
Uraninite
Uranophane-alpha
Uranospinite
Uvite
V
Vesuvianite
Villyaellenite
W
Wallkilldellite
Wawayandaite
Wendwilsonite
Willemite
Wollastonite
Woodruffite
Wulfenite
Wurtzite
X
Xonotlite
Y
Yeatmanite
Yukonite
Z
Zincite
Zinkenite
Zircon
Znucalite
Totals:
Mineral Species
Identified = 357
Unique Minerals = 28
(in bold)
34
References
Marcellus Shale
Ramsay, Barrett, The Depositional Setting of the Marcellus Black Shale, Independent Oil & Gas Association
of West Virginia, www.iogawv.com/RamsayBarrett-Shale.pdf
Smith, Taury, and Jim Leone, Utica and Marcellus Potential in New York State, http://esogis.nysm.nysed.gov/
Milici, Robert C., and Christopher S. Swezey (2006), Assessment of Appalachian Basin Oil and Gas
Resources: Devonian Shale—Middle and Upper Paleozoic Total Petroleum System, USGS Open File Report
2006-1237, http://pubs.usgs.gov/of/2006/1237/.
Piotrowski, R. G., and Harper, J. A., (1979). Black shale and sandstone facies of the Devonian "Catskill"
clastic wedge in the subsurface of western Pennsylvania. Eastern Gas Shales Project, EGSP Series 13, 40 p.
United States Department of Energy
Marcellus Shale – Appalachian Basin Natural Gas Play: http://geology.com/articles/marcellus-shale.shtml
Harper, John A. (2008) Pennsylvania Geology, v. 38, No. 1, PA Dept. of Conservation and Mineral
Resources, 24 p.
Pennsylvania DEP Maps: http://www.dep.state.pa.us/dep/deputate/minres/oilgas/2011PermitDrilledmaps.htm
Coal
Edmunds, William E., (2002) Coal in Pennsylvania (2nd ed), Pennsylvania Geological Survey, Fourth Series,
Educational Series 7, Harrisburg, 28 p.
Eggleston, J.R., Kehn, T.M., and Wood, G.H., Jr. 1999, Anthracite, in Shultz, C.H. ed., The Geology of
Pennsylvania: Pennsylvania Geological Survey, Special Publication #1, Ch. 36, p. 458-469.
Annual report of the Secretary of Internal Affairs of the Commonwealth of Pennsylvania, 1885, Vol. 13, PA
Bureau of Industrial Statistics, Harrisburg, 1886.
Hower, J.C., J.R. Levine, J.W.Skehan, E.J. Daniels, S.E. Lewis, A. Davis, R.J.Gray, and S.P. Altaner,
Appalachian Anthracites, Organic Geochemistry, vol. 20, no. 6, pp. 619-642, 1993.
Patrick, Kevin, Pennsylvania Caves and other rocky roadside wonders, 2004, Stackpole Books,
Mechanicsburg, PA.
Frantz, Aaron R., Edward L. Simpson, and Dale W. Freudenberger, Jorney into Anthracite, ed. Frank J.
Pazzaglia, Geological Society of America, Field Guide 8, 2006
Atlantic Coal (www.atlanticcoal.com)
Acid Mine Drainage
Cravotta, Charles A., III, Keith B.C. Brady, Arthur W. Rose, and Joseph B. Douds, Frequency distribution of
the pH of coal-mine drainage in Pennsylvania
USGS Annual Survey of Programs in Pennsylvania, U.S. Geological Survey Fact Sheet FS-038-96
Middle Susquehanna Sub-basin Year-2 Survey, Susquehanna River Basin Commission, Publication 269,
September, 2010.
Franklin Mineral Deposit
Dunn, Peter J. (1995), Franklin and Sterling Hill, New Jersey: the world’s most magnificent mineral deposit,
http://franklin-sterlinghill.com/dunn/index.shtml
The Franklin Mineral Museum website, http://franklinmineralmuseum.com
The Sterling Hill Mineral Museum, http://sterlinghillminingmuseum.org
The Fluorescent Mineral Society http://uvminerals.org
35
36
Notes
37
Notes
38