t493
The Canadian M ineralo gi st
vol. 37. pp 1493-1498(1999)
A NEW MINERALSPECIES,
ORLANDIITE,Pb3Gla(SeO3)'H2O,
AND AN ASSOCIATEDLEAD-COPPERSELENITECHLORIDE
FROM THE BACCU LOCCI MINE,SARDINIA,ITALY
ITALO CAMPOSTRINI ANOCARLO MARIA GRAMACCIOLI$
Dipartimentodi Scienzedella Terra, UniversitddeeliStudi,Via Botticelli23' I-20133Milano, Italy
FRANCESCODEMARTIN
Dipartimento di Chimica Strutturale e Stereochimica Inorganica,
Universitd degli Studi, Via Venezian21, I-20133 Milano, Italy
AssrRAcr
Orlandiite, ideally Pb:Cla(SeOr).HzO, is a new mineral species ftom a selenium-rich pan of the oxidation zone at the old
lead-arsenic mine ofBaccu Locci, near Villaputzu, Sardinia, Italy. The mineral is colorless to white, translucent, brittle, has a
vitreous to silky luster, and is not fluorescent in ultraviolet light. The calculated density is 5.66 g/cm3 for the ideal formula, with
= 1.96 (+0.05). An X-ray study carried out on a single crystal indicates a
Z = 2. The mineral is birefringent, with nreas= ncarc.
t r i c l i n i c s y m m e t r y , s p a c e g r o u p P( ln o . 2 ) , a 8 . 1 3 6 ( 3 ) , b 8 . 4 3 0 ( 6 c) ,9 . 2 3 3 ( 7 ) L , s 6 2 . 5 8 ( 7 ) , 9 7 1 . 8 + ( 4 ) , " y 7 5 . 1 3 ( 4 ) ' . T h e
strongestsix lines oi the X-ray-diffraction pattern ld in A!)(hkt)l are: 4.000(100)(002),3.258(75Xl2l). 3.188(75X201),
3.818(55)(201), 3.731(44)(122), and 2.103(40)(142). Orlandiite occurs as very small, elongate, tabular crystals up to 0.1 mm in
length, colorless to white, in association with chalcomenite, pseudoboldite, anglesite, quarlz and other selenites.The chemical
formula has been determined ftom electron-microprobe data and a crysta1-structue determination [final R index = 0 .042 on 1226
reflections with I > 3o(I)1. The structure contains two independent Pb atoms belonging to layers with idealized composition
PbClz; a third disordered lead atom is located between theselayers, together with a disordered SeO3group and the H2O molecule.
In most of the sites occupied by Cl atoms, there is a partial replacement by OH groups. Associated with orlandiite and
chalcomenite, and presently under study, is another new selenite, Pb+CuCl:(SeO:):(OH), in the form of minute lemon-yellow
aggregatesof tiny platy crystals. The strongest six lines of the X-ray diffraction pattem for this_phase ld irt A(l)(hkl)l are:
8.279(100X010),6.674(80X1l0), 11.100(76X001
),7 .344(70)(100),5.788(65X101),and 6.036(60)(112),which leadsto the following unit-cell data:a 8.290(8),b 10.588(13),c 13.587(15)A, u 124.a7$), p 110 60 (9),I 63.26(9)', arldZ = 2.
Keywords: orlandiite, new mrneral species,selenites,Baccu Locci, Sardinia, Italy
SowleInB
Nous prdsentons ici les caractdristiques de la orlandiite, nouvelle espdce min6rale dont la composition id6ale serait
Pb:CL(SeO:).HzO; elle provient de la partie riche en s616niumde la zone d'oxydation de l'ancienne mine de plomb-arsenic de
Baccu Locci, situde prds de Villaputzu, en Sardaigne,Italie. Le min6ral est incolore ou blanc, translucide, cassant,ayant un 6clat
vitreux h soyeux; il n'6met aucunefluorescenceen lumidre ultraviolette. La densitdcalculde est 5.66 g/cm3pour la formule iddale,
avecZ=2.Lemin6ralestbir6fringent,avecnmes=flcarc=1.96(t0.05).Unedtude-endifftactionXsurcristaluniqueindiqueune
sym6trietriclinique,groupe spatialP1 (no. 21,a 8.136(3),b 8.430(6),c 9.233(7)A, c 62 58(7), B 71.84(4),1 75.13(4)".Les six
riies les ptus inlenses du spectre de diffraction ta en A(f)(aOj sont: 4.000(100)(002),3.258(75X121), 3.188(75)(201),
3.8 I 8(55X20 1), 3 731(44)(122) er 2.103(40)(142). La orlandiite se prdsenteen trds petits cristaux incolores h blancs, tabulaires,
allongds,jusqu'd 0.1 mm en iongueur, en association avec chalcom6nite, pseudoboldite,angl6site, quartz et autres sdl6nites.La
formule chimique a 6t6 ltablie d partir de donn€es obtenues h la microsonde dlectronique et des r6sultats d'une dbauche de la
structue cristalline [R final = 0.042, 1226 rdflexions ayant I > 3o(I)]. La structure contient deux atomes ind6pendants de Pb
faisant partie de couchesde composition iddale PbClz; un troisibme atome est ddsordonndentre ces couches,en relation avec un
groupe SeO3ddsordonndet ra moldcule de H2O; dans la plupart des sites occupdspar le Cl, il y a un remplacementpartiel par des
groupes OH. Une deuxiBme nouvelle espdce,dtroitement associded la orlandiite et la chalcomdrute,fait pr6sentementI'objet
d'une 6tude; il s'agit d'un autre sdldnite, Pb+CuCI:(SeO:):(OH), qui se prdsente sous forme Q'aggrdgatsde plaquettesjaunecitron trds petites. Les six raies les plus intenses du spectrede diffraction de cette phase ld en A(I)(hkI)l sonf 8.279(100X010),
$
E-mail ad.dress:carlo@r10.tena.unimi.it
1494
THE CANADIAN MINERALOGIST
6.674(80)(110),
11.100(76)(001),1.344('70)(100),
s.788(65X101)
er 6.036(60X112),
ce qur mdne d la maille 6ldmentaire: a
8.290(8),
b 10.588(13),
c 13.587(15)
(9),t 63.26(9)",erZ=2.
4,o124.47(8),B 110.60
(Traduit par la Rddaction)
Mots-clds'.
orlandiite,nouvelleespbcemindrale,sdldnites,
BaccuLocci, Sardaigne,
Italie
INrnooucrroN
SSE direction. Such discontinuities were formed as a
result of tectonic readjustmentsafter the last episode of
The old lead and arsenic mine at Baccu Locci near intrusive activity, and were subsequentlymineralized by
Villaputzu, in southeasternSardinia, is one of several hydrothermal solutions. Veins are more or lessfrequent
hydrothermal ore deposits hosted in the Paleozoic within fractures, since the distribution of the ore miner"black shales" occurring in the well-known silver-rich
als depositedby the mineralizing fluids was controlled
mining zone of Sarrabus-Gerrei. The mine is situated by the mechanical behavior of the host rocks. Such an
at the northern border of this region and was exploited origin explains why stockwork-type structures are obfor about a century until the 1960s,when it was finally
served within the porphyries, whereas elongate
abandoned.Chalcomeniteconstitutesan interestins find
orebodies can be observed within the shale unit.
in the dumps; the quality of the crystals permitte-dthe
The tectonic breccia filling the fractures was probstructure refinement to be carried out on natural samoles ably impregnated by the ores, thereby resulting in an
for the first time (Pasero& Perchtazzi 1989;. Our iirst
unusual mineralization mainly consisting of galenaand
visit to the old underground workings in1996 resulted arsenopyrite in almost equal amounts. Accessory minin the discovery of exceptional specimens of chalco- erals are sphalerite, chalcopyrite, pyrite and pyrrhotite.
menite in some abundance,with crystals up to 2 cm in
The deposit is typically zoned,as can easily be observed
length, together with other secondary copper minerals in the upper part of the mine, where a surface zone, an
(seebelow), in some caseseven in fine specimens,and oxidation zone and a secondaryenrichment zone can be
a number of other selenites.In a Se-rich areain the mine, identified.
and in close connection with chalcomenite, two new
In the oxidation zone of the deposit (upper Santa
lead selenitescontaining essential amounts of chlorine Barbara level), there is a notable concentration of sechave also beendiscovered,one ofthem being orlandiite, ondary minerals, mainly anglesite, amite, brochantite
and the other PbaCuCl3(SeO3)3
(OH), which is presently and gypsum, with minor linarite, together with subordiunder study.
nate amountsof severalother species,such as atacamite,
Orlandiite is named in honor of Paolo Orlandi (b. bayldonite, beaverite, carbonate-cyanotrichite,chalco1946), AssociateProfessorof Mineralogy at the Univeralumite, chalcophyllite, chlorargyrite, devilline, olivensity of Pisa, who has been very active in determining new
ite, osarizawaite, pseudobol6ite, pyromorphite,
minerals and mineral occurrences in Italy. The new minserpierite, smithsonite, spangolite, native sulfur, vanaeral and name have been approved by the IMA Commisdinite and wulfenite. In addition, there is a local consion on New Minerals and Mineral Names (No. 98-O38): centration of selenites, especially chalcomenite; a
Type specimens,including the holotype, are deposited rn detailed illustration of these minerals is given in
the mineral collection of the Department of Earth Scr- Gramaccioli et al. (1997).
ences at the Universitd degli Studi, Milan, Italy.
Orlandiite occursin thesechalcomenite-richconcentrations as very small elongate tabular crystals (up to
Occunr.sNce
0.1 mm in length), which are colorless to white, and in
places associatedwith lemon-yellow aggregates(up to
A description of the Baccu Locci mineral deposit is 0.1 mm in diameter) of platy crystals of the other new
given in Zucchetti (1958a,b) and Bakos et at. 1Seg.
phase (hereafter referred to as the "second phase").
The ore mainly consistsof galena and arsenopyrite,and These are generally found together with chlorides, such
occurs within sedimentary and igneous formations of
as green atacamite or very small small dark blue cubes
lower Silurian age; these formations are covered by a of pseudobol6ite or, much more rarely, with chlorartransgressiveformation of Eocene age (Monte Cardiga gyrite of an unusual pale pink color. In the same assotransgression). The Paleozoic sedimentary rocks are ciation, there are several other selenium oxysalts, all of
typically representedby black shales,whereasthe igne- them in very minor amounts with respect to chalcoous rocks are typically representedby porphyries. The menite, which is by far the most abundantselenium-rich
unconformity between the Silurian and Eocene sedi- mineral.
ments is quite distinct, and can be easily noticed in the
Among these oxidized selenium-bearing minerals,
landscapeof the nearby mountains.
there are elongatebundles of olsacheriteor, much more
The Paleozoic terranes are crossed by a series of
rarely, mandarinoite, in small spherical aggregatesof
subparallel fractures and faults oriented along a NNWprismatic yellowish greencrystals.At the outermostpart
1495
ORLANDIITE, A NEW MINERAL SPECIES, SARDINIA, ITALY
ofthe selenium-rich concentrations,we found attractive
blue crystals of schmiederite, in cases closely resembling linarite, or francisite in earthy green masses.A
detailed study of all these secondary minerals is in
progress. In some aspects,the assemblageof selenium
minerals at Baccu Locci appearsto be rather selective,
since some of the most widespread selenium oxysalts
are altogether absent. For instance, notwithstanding a
persistent and systematic search,no clinochalcomenite
has ever been found at the locality, and in spite of the
presenceof lead and the seleniteion, no molybdomenite
or kerstenite has yet been identified in this association.
Similarly, with the exception of a single nodule (1
cm in diameter) consisting of a solid solution of
clausthalite (PbSe) and galena in almost equal proportions (PbS = 57 mol7o), no pure selenides have been
discovered yet in the locality; most of the unoxidized
ore in the assemblageconsists of galena, covellite, and
arsenopyrite.
Pnvsrcar- A\D OPTTcAL
Pnopennss
Orlandiite forms elongatetabular crystals (Figs. lA,
B), invariably twinned on {010}; they are brittle, white
to colorless, with a vitreous to silky luster and a perfect
cleavageon {010}. The secondphaseappearsas very
small aggregates(100 pm in diameter) of lemon-yellow platy crystals, up to 10 pm long and 2 pm thick.
Neither mineral is fluorescent in either short-wave
(254 nm) or long-wave (366 nm) ultraviolet light. They
can be easily distinguished from each other using the
stereo-microscope,and with someexperience,also from
olsacherite, and from much more common minerals
such as pyromorphite, gypsum, or vanadinite.
The measurementof the optical properties of these
lead selenitesis very difficult, owing not only to the very
small size of the crystals, but also to their strong reactions with all available liquids of high index of refraction. Thesereadily attack the minerals, turning them into
a black opaque residue, thereby preventing any useful
observation with a petrographic microscope. The only
possibility in this respect was to measurethe Brewster
angle with the optical goniometer; in this way, in spite
of the extremely small size of the grains in polished
mounts, we obtained approximate values of the mean
index of refraction n = 1.96 (t0.05) and 1.83 (10.05),
respectively, for orlandiite and the other new phase.If
the values of the calculated densities from the unit cell
and the chemical composition are consideredfor the two
minerals(D"ul"= 5.66 and5.25g/cm3,respectively),the
corresponding estimates of the mean indices of refraction using the Gladstone-Dale rule and Mandarino's
(1981) constantsand criteria are 1.96 and 1.87,respectively. These are in excellent to good agreement with
observedvalues.
For orlandiite, the infrared spectrum recorded in
transmission on a very small crystal using an FT-IR
infrared microprobe shows sharp absorptions due to
HzO and the OH group (3410-3160 and 1586 cm-t),
and absorptionsat 788 and724 cm-r due to the selenite
group (Ross 1974).For the other new phase,the IR spectrum recorded from a very small grain using the same
instrument and conditions shows sharp absorptions in
the OH region (3700-2900 cm-l) and absorptionsat 810
and 738 cm-1 due to the selenite group.
Cupt'rtcal CovrposrrloN
Electron-microprobe analyses (wavelength dispersion) of the two phases were performed on polished
grain-mounts using an ARL-SEMQ instrument of the
Italian National ResearchCouncil (C.N.R.) at Centro di
studio per la Geodinamica Alpina e Quatemaria,Milan.
The standardsand operating conditions are reported in
the footnote of Table 1. Because of the very small
amount of material available, no direct determination
of the HzO content has been carried out. For orlandiite,
the amount of H2O present in the mineral has been deduced from the results of crystal-structure refinement,
and for the other new phase,the correspondingamount
has been deducedfrom the OH content basedon charge
balance. In both cases,the total is very reasonable.In
order to overcome volatilization of water and possibly
oflead chloride, the electron beam was set at a diameter
of 15 pm during the analysis ofboth minerals. The resulting chemical formula for orlandiite is in good agreement with that obtained from crystal-structuredata.The
only possible check for the other phase, for which the
crystal structure is unknown, was to consider mass and
charge balance (which needs some OH); the total ls
close to 1007o.
TABLE I CIIEMICAL COMPOSMON OF THE NEW LEAD SELEMTES
FROM BACCU LOCCI. SARDINIA. ITALY
W€/o
Orlmdiite
cl
Pbo
sd"
so,
ZtO
cdo
CuO
F€O
HrOLessO=Cl
Total
1435
741E
1231
o2o
0 35
0 1l
0 39
0.42
234
3 24
10141
Ruge
'1328-15 33
1173-7549
tt 9t-12 52
012-037
0 15--080
007417
0 20-4 8l
0 40-4,43
Thoretical
1373
15 50
1167
220
310
10000
S@ond
nwpmw
841
61 26
2484
o14
t75
144
429
040
0 ll
18E
10076
Raoge
Thoretical
8 29-{ 49
5997 12 11
23 90_259t
0 12-016
1 69-1 9l
1 24-r 55
40t441
0 38-041
8 35
60 80
U 67
0 14
1 74
1 43
424
0 40
011
188
10000
* From the structure deemimtioo
ud chuge balmce (relative to OII)
at the elstrotr microprobe: eiglrt for orlodiite, six for the s@nd
Numbq ofusllss
rcltage 20 kV, smple cE@t on brass I 5 nA
nw phase. Adoating
stmduds: phosgmite (Cl), dglesite (Pb, S), pue m€tals (Se, zq C4 Cq Fe)
from tbe
Theoretical composition. for orlmdiite md for the second new phe'
ud
mpirical chmicat fomulae Pb,(C1..*OIt,Js(Seq)'EO
(Pb3 ,aCd. rr)x3 sr(Cuo rrZno r"Feo.or)", 'oCl.[(Ser orSo o,)"r.o.Or]3(OH0 ?7Cl0r3),
rcspectiwly
t496
THE CANADIAN MINERALOGIST
FIG. 1 Orlandiite, tabular elongate crystals on matrix. Photos taken with a Hitachi scanning electron microscope. The maximum length of the crystal aggregatesis 150 pm.
Whereas in orlandiite lead is the only cation present
as an essentialconstituent,other cations, such as copper
as well as lead, seemto be essentialin the secondphase.
On crystal-chemical grounds, zinc and cadmium are
very likely substituentsfor copper, and probably also
iron. For this reason, all these elements have been
grouped in the proposed chemical formula. For
orlandiite, minor amounts of these sameelementshave
also beenfound; with the possible exception of Cd, they
are not considered to be likely replacementsfor Pb in
the sfiucture and have been omitted from the chemical
formula.
X-Rev Dare
The determination of accurate X-ray crystallographic
data of orlandiite was particularly difficult, owing to the
scarcity of suitable material. Single-crystal data show
the mineral to be triclinic Pl (no. 2), with a8.136(3), b
8.430(6),c 9.233(7)A, a 62.58(7)', B 71.84(4)', 1
75.13(4)",andZ= 2. Powder-diffractiondata obtained
using a Gandolfi camera are reported in Table 2. From
thesedata,-aunit cell with a 8.146(12),b 8.428(22),c
9.241(22) A, a 62.32(2r), g 7 r.64(17), 1 75.22(19)" can
be deduced,in good agreementwith the resultsobtained
ORLANDIITE, A NEW MINERAL SPECIES, SARDINIA, ITAIY
TABLE 2 X-RAYPO\I'DER-DIFFRACTION DATA
FOR ORT^ANDIITE*
hkt
d*"
(A)
001
101
002
201
122
022
t2l
201
113
T22
8 090
5 010
4 000
3 818
3 731
3 548
3 258
3 188
3 046
2489
2728
2 666
2 s64
2 484
003
300
J'1
dd
(47 A)
rlI"
'7
965 3 6
4 982 7 1
3 983 100
3 E 1 3 fi
3 552
3 261
3 lEl
3 051
2,881
2728
2 655
2 5s5
2 447
44
1t
75
75
4
6
38
hkl
t23
124
024
142
320
223
t44
l4l
322
143
205
501
28
t2
de,
dd
(A)
(A)
2 365
2298
2 r73
2 to3
I 989
I 953
I 875
| 84'.1
I 812
| 760
I 606
| 444
1 441
2368
2298
vI"
23
7
2 107 40
I 986 u
1 957 3
I 871 l l
I 845 6
18li
10
1 764 9
1 608 6
1 445 4
'7
r 440
* Gmdolf mqa (dimets 1146 m), Ni-filts€d Cu/(s radistim Intmsities
oalolated on the bsis ofthe crystalstructre
TABI.E 3 X-RAY POWDER-DIFFRACTIONDATA
FOR TIIE SECONDPIIASE*
doa
(A)
ddw
(A)
dd
(A)
vL
(A)
301
524
031
035
222
T4s
343
T44
2545
2 s20
2462
2440
24tt
2388
2361
2331
2297
2214
2548
2 519
2458
2445
24ll
2389
2365
2330
2298
2212
20
20
20
20
20
20
20
20
25
20
35)
) a<1
a a<a
an
IUJ
2208
2 154
2 r33
2106
2079
2065
2043
2028
1 921
| 760
1742
I 700
1 686
2208
2 t54
2 134
2tO4
2074
2064.
2040
2025
I 919
| 759
t74t
l 699
1 685
20
20
20
t5
15
15
15
20
15
l0
l0
10
15
hhl
de
149'l
8.290(8),b 10.588(13),c 13.587(15)
A, a 124.47(8),9
I 10.60 (9), 1 63.26(9)", and Z = 2 canbe deduced,and
the reflections are indexed on this basis.
The single-crystal data for orlandiite were obtained
using a Enraf-Nonius CAD4 diffractometer; the crystal
structure was solved by direct methods and refined using 1226 reflections with I > 3o(I); the final R index is
0.042. Full details of the crystal structure will be published in a separatepaper (Demarttn et al., in prep.). The
structure contains layers with idealized composition
2PbC12and PbSeO:.H2O, respectively, alternatively
stacked along [100]. Two independent Pb sites belong
to the PbClz layers and display tricapped-trigonal prismatic coordination, similarly to that observed in a number of other minerals containing lead and chlorine
laurionite group, barstowite PbaCl6(CO:).HzO:
Merlino et al. (1991,1993,1996)1.
The PbSeO3'!l2O layer displays extensive disorder
due to the splitting of the Pb site into two different positions, having a population of about0.75 and 0.25, respectively; a corresponding splitting also is observed for the
selenite groups. Such a statistical disorder can be considered as a random stacking of the PbSeO3.H2O layers in
the crystal, with the prevalence of one configuration.
DrscussroN
001
010
100
ll0
112
l0l
022
102
Tl1
023
221
200
201
02r
tt2
122
114
103
224
203
212
215
* From I D-m
ll 100
8 279
1 344
6674
6 036
5 7EE
456E
4 335
4 142
4 105
3 840
3 742
3 685
3 635
3371
3314
3247
3224
3 144
3034
2a03
2724
2664
2 565
lt 104
I 255
1 338
6665
6 064
5'182
4537
4 309
4 171
4 tOO
3 839
3 769
3 669
3 630
3369
3311
3243
3215
3 142
3032
2797
2726
2659
2 559
76
100
70
80
60
65
45
40
40
44
40
30
30
35
40
30
25
25
35
30
23
30
20
20
22s
5Zt
226
T3r
016
040
423
42r
o46
4t6
106
235
r46
Rigakudifrrctonetq, N-fihsed CuKo ndiatiotr
from single-crystal data. The larger values of the estimated standard deviation obtained in this way are due
to the paucity of pure material available to record the
spectrum.
For the second phase, of which no adequatesingle
crystals could be found, only powder dataarc available
(Table 3). From these data, a triclinic unit cell with a
The presence of a variety of secondary selenium
minerals at Baccu Locci is notable becauseof the rarity
of these minerals in nature. This locality seems to be
the richest in selenium oxysalts in the world, after the
celebrated El Dragon mine in Bolivia (Grundmann er
al. 1990, Mandarino 1994). A particular characteristic
of the Baccu Locci selenium-rich assemblage is the
presenceof a significant number of chloride minerals.
This strongly suggeststhe essential presenceof chlorine for such a paragenesis,and a requisite threshold
concentrationof the chloride ion in the depositing solutions.
In recent years, a number of chloride-containing selenites have been discovered in nature as minerals deposited by fumarolic activity around the crater of the
Tolbachik volcano in Kamchatka, Russia (see, for instance,Vergasovaet al. 1989,1997,1999, Semenovaer
al. 1992, Krivovichev et al. 1998). The presenceof selenium compounds in the fumarolic depositsfrom Vesuvius
was noted long ago (Zambonini & Coniglio 1925).However, none of the minerals deposited in fumaroles bears
any chemical or crystallographic resemblance to the new
phasesdiscovered at Baccu Locci. Without entering into
detailed geochemical discussions,it is not difficult to
imagine that the conditions of formation are drastically
different, the volcanic occurrences being the result of
deposition from a vapor phase at higher temperature and
a much lower pH than at Baccu Locci.
The presenceof chlorides in the secondaryminerals
may possibly be due to the Eocenetransgressionevent,
at a stagewhen the deposit was covered by the sea.
t498
AcrNow-goceueN'rs
We are grateful to the courteous assistance of
Messrs. Antonio and Raimondo Manca from Lanusei,
who led us to the Baccu Locci mine; essentialhelp in
freld collecting was provided by Dr. Paolo Biffi and Mr.
Luigi Saibene. Assistance in performing the chemical
analysis with the electron microprobe was provided by
Dr. Valeria Diella and Mr. Danilo Biondelli of the
Centro Studi per la Geodinamica Alpina e Quaternaria
of the Italian National ResearchCouncil (C.N.R.). Dr.
Lucia Carlucci helped in the acquisition of the IR spectra. Drs. R.F. Martin and W.D. Birch provided considerable help in revising the manuscript. We are also
particularly indebted to C.N.R. for financial help in the
proJect.
RBreneNces
Int. Conf. on Polytypes, Modulated Structures and
Quasicrystals,Balatonszeplak, Hungary.
&-
(1993):Crystalstructureof
paralaurionite and its OD relationships with laurionite
M ineral. Mag. 57, 323-328.
(1996): Struttura della
& _
barstowite PbaClo(CO:).HzO. Plinius 16, 151-152.
PASERo,M. & PERcHIAzzt,N. (1989): Chalcomenite from
Baccu Locci, Sardinia, Italy: mineral data and structure
refinement. Neues Jahrb. Mineral.. Monatsh.. 55 1-556
Ross, S.D. (19'14): The infrared spectra of minerals (V.C
Farmer, ed ). Mineral. Soc., Monogr. 4,423-444.
SsMENovn,T.F., RoznossrvENsKAyA, I.V., Fnerov, S.K. &
VERGAsovA,LP. (1992): Crystal structure and physical
properties of sophiite, a new mineral. Mineral. Mag. 56,
ut-245.
Beros, F., CmcnNcru,G.,Fnoo.l,S-&M,tizznrrr. A. (1991):
The Au-Ag-As-Fe-Cu-Pb-Zn-Sb-W paragenesisof
BaccuLocci: an exampleof multistageevolutionfrom a
protoreof volcanic-sedimentaryoigin. Proc. Zuffar' days
'88, 9 (abstr.).
V E R G A s o v A ,L . P . , F r l . q r o v , S . K . , S e v p N o v e , T . F . &
FnosoFova,T.M. (1989): Sofiite, Zn2(SeO:)Clz,a new
mineral of volcanic exhalations. Zap. Vses. Mineral.
Obshchest.118,65-69 (in Russ.).
Gnevnccrorr,C.M., Celrposrnnr,I. & Sren-l,P. (1997):Die
BaccuLocci Mine (Villaputzu,Cagliari) auf Sardinien.
ktpis 22(9),13-26.
T F.. Ftr-ATov.
KRrvovrcHEv. S.V.. Snrr,rBNove.
S.K. & Au,q.NIBv,V.V. (1999): Chloromenite, CuqOz
(SeO:)+Clo,a new mineral. Eur. J. Mineral ll, 119-123.
GmrNorureNx,
G., LeHRBBncBn,
G. & ScuNonruR-Korfl-ER,
G.
(1990):TheE1Drag6nmine,Potosi,Bolivia.Mizeral.Rec.
21,t33-t46.
SnNENove. T.F.. Ssuvr,lov. R.R., Fruq.rov, S.K.
a
& ANemBv, V.V . (1997): Ilinskite, NaCu5O2(SeO3)2C13,
new mineral of volcanic exhalations. Doklady Russ.Acad.
Sciences. 353. 641- 644.
KRrvovrcHEv,
S.V., Frlerov, S.K., SerasNov,q,
T.F. &
RozrnesrvsNsKAve,
I.V. (1998):Crystalchemistryof in- Zarr.rsoNlNr,F. & CoNrcr-Io, L. (1925): Sulla presenza di
organiccompoundsbasedon chainsof oxocentered
tetracomposti solubi[ de1 selenio e del tellurio tra i prodotti
hedra.I. Crystalstructureof chloromenite,
CuqOz(SeO:)+
dell'attuale attivitd del Vesuvio. A nn. R. Osserv. Vesuviano
)1
C16.Z. Kri stallogr. 2I3, 645-649.
MeNo,qnrNo,
J.A. ( 1981): The Gladstone-Dalerelationship. ZuccHETrr, S. (1958a): The lead-arsenic-sulfide deposit of
IV. The compatibilityconceptand its application.Can.
Baccu Locci (Sardinia-Italy). E con. Geol. 53, 867 -876.
Mineral. 19,441-450.
Naturalandsyntheticselenites
andselenates
-(1994):
and their Gladstone-Dalecomoatibilitv. Eur. J. Mineral.
6,337-349.
(1958b): Il caratteristico deposito a solfurati di
_
piombo e arsenico di Baccu Locci (Sardegna).Boll. Sent.
GeoI. It. 53,275-3Ol
Mnnrnvo,S.,P.Aseno,
M. & PERcHrAzzr,
N. (1991):OD-structures amonglead hydroxychlorides:fiedlerite-lA, fied- Received March 26, 1999, revised manuscript accepted Noleite-2M and laurionite-paralaurionite 1n MOSPOQ'9I
vember 17, 1999.