1305
The CanadianMineralo gist
Vol. 34,pp. 1305-1315(1996)GALLOBE
UDANTITE,PbGasl(AsO4),(SOdl2(OH)e
A NEWMINERALSPECIESFROMTSUMEB,NAMIBIA,
AND ASSOCIATEDNEWGALLIUMANALOGUESOFTHEALUNITE. JAROSITEFAMILYJOHNL. JAMBOR
Depanmentof EarthSciences,
Universityof Waterlao,Waterloo,
OntarioN2L3GI
DeALTON R. OWENSCANMET,555BoothStreet,Ottawa"OntarioKIA 0Gj
JOELD. GRICE
Research
DivisiouCanadianMuseurnof Nature,P.O,Box32143,
StationD, Ottrwa.OntartoKP 6P4
MARKN.

FEINGLOS

Duke UniversityMedical Center,Box 3Q21,Durham,North Carolinn 27710, U.S.A.
ABSIRA T
Gallobeudantite,ideally PbGar[(AsO),(SOJ]z(OII)e, is the newly defined Ga analogueof beudantite.It occursas zoned
rhornbohedr4up to 200 pm alongan edge,in vugsin a singlespecimenof massiveCu-bearingsulfidesfrom Tsumeb,Namibia.
Gallobeudantiteis variably pale yellow, greenish,or cream-coloredwith a white to pale yellow streak,vitreous luster, evento conchoidalfracture, hardnessof 4, and D(calc.) 4.61 glcm3for Z = 3. The mineral is nonpleochroic,uniaxial negative,
c01.763(5),€ 1.750(5).A single-crystalX-ray refinementof the structure(R = 0.078) showedthe mineralto be rhombohedral,spacegroup R3n, a 7.225(4),c 17,03(2)A, and isostructuralwith corkite. The strongestlines of the X-ray powder-l{iffraction
pattem[d in A(/)(hl<l)]we:.5.85(90X101),
3.59(40Xll0), 3.038(100X113)
and2.271(40)(107).
Within the crystals,in addition
to gallobeudantite,arezonescontainingGa-richbeudantiteandhidalgoite,andthe unnamedGa analoguesof segnitite,corkite,
kintoreite, and arsenocrandallite.
The last contains\p to 1,2.7wt.VoGeO2,which is aboutT\Vo of the Ge substitutionpossible
if the formula is assumedto be Ca(Ga,AI,Fe)2Ge4r(AsOr2(OtI)6.
The new namegallobeudantitealludesto the preilominanceof Ga in thepositionoccupiedby Fe3*in beudantite-typeminerals.
Keywords: gallobeudantite,new mineral species,description,crystal structure,alunite - jarosite family, gallium analogue,
nomenclature,Tsumeb,Narnibia.

Souuanr
La gallobeudantite,de compositionid6alePbG,a3[(AsO/,(SO)]2(OH)u,est l'6quivalent gallilere nouvellementd6crit de labeudantite.Elle se prdsenteen rhomboddreszon6s,jusqu'l 200 pm de c6t6, dansles cavit6sd'un seul 6chantillonde sulfures
massifsde cuiwe provenantde Tsumeb,en Namibie.l,a gallobeudantitea une couleurvariable,jaune pdle, verddtre,ou crdme;
el1epossbdeune rayureblanchei jaune pdle, un 6clat vitreux, une cassure6galed conchoidale,une duret6de 4, et une densit6
ca1cul6ede4.61
glcm3powZ=3.C'estunmin6ralnonpl6ocbro'r'que,uniaxen6gatif,rol.763(5),e1.750(5).Unaffinementde
la sffuctue (R = 0.078)montrequ'il s'agitd'un mindralrhombo€driqrie,groupespatialR3m,a7.225(4),c 17.03Q)A, ayantla
m6mestructureque la corkite. I-es raiesles plus intensesdu spectrede diffraction (m6thodedespoudres)U en A(4(&&I)l sont:
5.85(90X101),3.59(40)(110),3.038(100X113)
et2.n\40)(IO7). A lint6rieur descristaux,en plus de la gatlobeudantite,
se trouvent deszonescontenantbeudantiteriche en Ga et hidalgoite,et les analoguesi Ga de segnitite,corNite,kintoreite, etarsenocrandallite,toujours sans noms. Cette dernidre contient jusqt'd l2.7Vo GeO, (poids), ce qui est environ 75Vo dtt
remplacementpossiblepar le Ga si on supposela formule Ca(G4Al,Fe)2Gea(AsOf2(OII)6.k nom de I'espbcenouvelle,
gallobeudantite,fait allusion i la prddominancedu Ga dansla position du Feh dansles min6rauxde type beudantite.
Keywords: gallobeudantite,nouvelle espdcemin6rale,description,structue cristalline, famille de falunite et de lajarosite,analoguei gallium, nomenclature,Tsumeb,Narnibie.

1306

TIIE CANADIANMINERALOGISTINTRoDUcrroN
62.4 61.9 63.8
42.3
32.7 32.6 32.1
A.4
Gallite,CuGaS2,
Ga(OH)3,originally Cu, wt% 42.5
andstihngeite,
0.4
0.4
0.5
0.7
1.7 2.3
2.0 2.0
2.t
Zl
1.6
describedfrom occurrencesat Tsumeb,Namibia, are Fe
2.0
1,7
1.4 1.1 t-7
13.3 13.5 13.2
0.4
0.4
0.3
32.1 31.2 31.0
0.4 0.5
0.5
the only previously well-defined minerals containing Ga
63
6.1
6.4
1.9
0.4 0.6 0.1
7.5 7.6
Ge
1.4
Ga as an essentialconstituent.The Ga analogueof
1.6
1.6
0.0 0.0 0.0
t.8
1.9 1.1
n.4
33.t 329 32.9
32.6 32.4 32.8
AA&3.
jarosite KGa3(SO)2(OH)6was synthesizedby s
99.9
100.7
100.7
993
100.1 100.3 100.5 t01.0 100.7sm
2A atotu
Dutrizac (1984),who demonstratedthat Ga substitutes
4 dorcfomta
htuata, 33 tutu
ftftula7.15
6.94
0.98 Cu6.89
l.@10.57 10.55 10.49 Cul.m
LU
for Fe injarosite-typestructures,
andthatthe resulting Zn
zn
0.49
0.50
0.49
9M.
S,04 0.04
6.9s 6.98 1.19
11.06 11.04 10.99Ca 0.91 0.87 0.87
solid-solutionsare nearly ideal chemically.We report
Fe 0.05 0.06 0.06
here on the natural occurence of extensiveGa substi- Fe
0.60
3-76 3.83 3.72 Zn 0.02 0.05 0.07 Ce 0.62 0.O
qll Ge-oJ! oJE 0]02 Fe 0.25 021
021
0.09 0.ll
tutions in minerals of the jarosite - alunite family as Ga
0.99 1.00 1.02 Go 0.04 0.04 0.03
3.85 3.94 3.83
found in a single specimenfrom Tsumeb, Namibia.
0.14
As oJloJl
1.06 1.02 0.98
r.63 r.66 l.n S 2.01 2.00 2.00
Included in the descriptionis the new speciesname Ce
gio
0J6
!.3!
gallobeudantite, which has been approved by thes 12.00 12.00 ll.6E
2.0t 2.06 2.08
Commission on New Minerals and Mineral Names"s
16.07 15.97 16.ll
IMA.
PRZ @r4lion
Most Ga is commerciallyproducedas a by-product Analys d 20 kV, 20 nA, 2$mnd @unt ntg TtMr Northm(Cu"Fe,Sl synthetic Fetu2 (A3), Ce neel (Ge)'prcgm.
Stsdeids: chal€prribfrom the treatmentof bauxite ores,but the Apex mine synthdio TmJcqorz (Ca), $halerite (Zn).
in Utah wasuniquein that it operatedbriefly in the late1980ssolelyfor the purposeofproducingGa and Ge.
Theseelementsat Apex arecontainedin limonitic ores
derived by the oxidation of Cu-Pb-Zn-Ag sulfide
veins in dolomite (Bernstein1986, Hopkins 1985). mainly of aligned inclusions of renierite, up to
Jarositefrom the Apex depositwas reportedto contain I x 3 mm, in a granular matrix consistinglargely of
up to 0.70 wt.VoGa (Dutrizac et al. 1986).The new a mineral that gives a germanite-likeX-ray powder
namegallobeudantitealludesto the predominanceof patlern,but with a compositionmuch too Cu-rich to be
Ga in the position occupiedby Fe3+in jarosite-type germanite(Table 1); the latter is under further study.
minerals. The original specimenis from the private The renierite (Table l) containsirregular inclusionsof
collectionof oneof the authors(M.N.F.), but the single gaUite(Table 1) up to 75 pm across,andoneendofthe
crystal used our study of gallobeudantiteis in the section is texturally complex and containsinclusions
Canadian Museum of Nature, Ottawa; as well, a of Sb-free gallian (0.3 .trt.VoGa) tennantite.A thinpolished section of the sulfide-rich matrix of the rim of chalcociteemphasizesthe granular texture of
specimen,and sectionscontainingthe analyzedgrains the germanite-likephase,and all minerals are cut by
describedhere,are in the SystematicReferenceSeries irregular,hairline veinletsof chalcocite.
Disseminatedon the surface of the specimenareof the National Mineral Collection of Canada"housed
at the Geological Survey of Canada, Ottawa. The local, minute patchesof hematiteand goethite,sparse
original specimenwas labeled "fleischerite" and is crystals of stolzite, and dots of spongy mercurian
believedto havebeencollectedin about 1960.when silver. One end of the specimenhas a thin, disconfleischerite was first described:the level of the mine tinuous veinlet, about 1 mm long, of otjisumeite,from which the specimenwas extractedis not known. PbGe4Oe.
Tsumeb is a world-famous mineral locality partly
becauseof the unusual geochemistryof its primary Pltysical and optical properties
ores,andpartly becausesupergenealterationhasled to
Gallobeudantiteoccursin the vugs as zoneswithin
the developmentof an extensive suite of secondary
minerals, many of which are of display quality. crystalsthat show an extensiverangeof mutual solidBeudartite, and now gallobeudantite,are among the solution involving As, P, and S. The crystals aremineralsin the secondarysuite.
sparsely disseminatedrhombohedraup to 200 pm
alongan edge.Someof the rhombohedrashowa minor
GAI-L0BEITDANTnE
modificationby {001}. Single,compositionallyzoned
crystals do occur, but most are multiple grains, too
Gallobeudantiteoccursin vugs in a single,blackish sparseto be describedas aggegates.Most crystalsare
specimen of massive copper ore, approximately <100pm in size,andhavea Ca-Ga-AsO,beudantite3 x 5 x 1.5 cm. The vugs are megascopically type analogueas the outermostzone. Gallobeudantite
inconspicuous,and the crystals within the vugs are is pale yellow, to slightly greenish,to cream-colored,
not noticeable unless examined with a binocular and is transparent,with a vitreousluster,white to palemicroscope.A polished section of one end of the yellow streak,and a Mohs hardnessof 4. The mineralsoecimen showed that the host material consists is brittle, giving an even to conchoidal fracture; theGALLOBEUDANTITE"A NEW MINERAL SPECIES.TST]MEB.NAMIBIA

r3w

evennessmay be an indicationof the {001} cleavage
that is present in other members of the beudantite
group. Density could not be measuredbecauseof
the small grain-size; for Z = 3, Dcacis 4.87 g/cm3
for the idealized formula and AsOo:SO4= li|.
Gallobeudantiteis nonfluorescent,and in immersion
oil is nonpleochroic,uniaxial negative,ro 1.763(5),e 1.750(5)at 589nm.
Composition
Electron-microprobe compositions for gallobeudantitewereobtainedwith an JEOL 733 instrumenr
operatedat 15 kV and with a beam current of 20 nA,
using l0-second counting times, the Tracor Northern
PROZA correction program, and the following
standards:apatite@) from Durango,Mexico, Ge metal(Ge), and synthetic GaAs (Ga), ZnFe"Oo(Zn,Fe),PbSO4Gb,S), A12O3(Al), InAs (As), and CaTiSiO5(Ca). As most of the analyzedzoneswere found to beslightly unstable under the electron beam, analyzed
areaswere restrictedas much as possibleto thosewith
dimensionslarge enoughto permit movementof thespecimenduring dataacquisition.Gallobeudantitewas Flc. 2. BSE image of poorly polished grain consisting of
among the least stablephases,and the POoanalogue
Ga analogueof segnitite (arca 2.2, Table 2) and gallian
hidalgoite (2.1, Table 3). Bar scalerepresents50 pm.
was the most stable.
Figures I to 7, inclusive, illustrate typical zoned
grains containinggallobeudantite,for which electronmicroprobe compositionsare given in Table 2. The
average composition derived from six analysesin

Flo. l. Back-scattered-electron@SE) image of zoned grain FIc. 3. BSE image of zoned grain consisring of gallocontainingareasof gallobeudantite(analyses4.2, 4.4, and,beudantite(7.1,Table2), gallianbeudartite(7.0,Table3),
4.7 in Table2). Znne 4.3 is a PO, aaalogueQable 3). A
andgallian hidalgoile (7.2, Table3). Outerrnostzone(7.3)
narow outermost zone, not visible in the photograph,is the Ca analogueof gallobeudantite.Bar scalerepresents
consistsof the Ga analogueof arsenocrandallite.
Bar scale
20um.
represents10 pm.

1308

TI{E CANADIAN MINERALOGIST

Fro. 4. BSE imageof zonedgrain consistingof gallo- FIG.6. BSEimageof zonedgrainin which darkcore(X)(PS3-AIin(5.4,Table2; 5.0 and5.2 aresimilar).Dark
of gallobeudantite
consistsof POoanalogue
beudantite
Table4), andlight grcy zote (X 2) is gallobeudantite.
Barscalerepresents
outerzone(5.7)is gallianhidalgoite.
50 Pm.
Barscalerepresents
20pm.

positionis characterizedby a predominanceof (AsO),
Table2 is Pb1.sa(GaszeFeffizAb.ozzoo.rd6.6[(AsOJr.r+(SOro.sol>2.00(Olt)s.sa,
which is the Ga analogueof substantialsubstitution of (SO) for (AsO), andbeudantite,idealized as PbFel+[(AsOr,(SOr]2(OH)6. negligible @O). The predominanceof (AsO/ in zone
As is evid9nt from Table 2, Gu Fe, and Al show 6.1 Cfable2) is sufficiently large that the composition
considerablemutual substitution in the mineral. correspondsto the Ga analogueof segnitite,the latter
whereasthat involving Zn and Ge is minor. The XOa ideally PbFel+H(AsO/2(OFI)6.The compositions of

Rc. 5. BSE imageof zonedgrain consistingof core of gallian
beudantite (2.0, Jable 3) rimmed by POaanalogueof
gallobeudantite,(2.2,Table4), which is.in tur4 rimmed
by grillobeudantiteQ.1\ Tahle 2); area 2.3 is Al-tich(up to l0 wt.Vo y'.J,2O)gallobeudantite.Bar scale
represents20 Pm.

Frc. 7. BSE image showingPOaanalogueof gallobeudantite(PS3-D, Table 4) and a whiter zone of gallobeudantite.
Bar scalerepresentsl0 pm.

1309

GALLOBEUDANTITE, A NEW MINERAL SPECIES,TST]MEB,NAMIBIATASLB 2. ELECTROTI.MICROPROBE COMPOSITIONS OF GALLOBETJDANITIE

Fis.l
Fis.2 Fi&3
Fis.4 Fis.5
5.4 z.la
6.1
42
4.4
4.7 2.2t
1.1
30.4
30.1 30.4 29.6
Pbo.rvtrlo 32.1 30.8 32.2 29.7
cao
0.0
0.0
0.0
0.0
0.0
0.0
0.0 0.0
ZnO
22
0.6
2.0
0.0
0.6
0.6
0J
0.0
Ga.o,
18.5
19.8 19.8 17.6
192 18.4 20.0 19.5
4.7
13.3
10.6 10.1 4.0
FerO,
Z9
122
3.1
5.5
1.5
3.0
3.0 7.6
Alros
8.9
2.3
8.1
l8.l
18.7 m2 X.9
Aqo,
16.0 18.6 16.6 25.0
J.0
9.0
9.0
82
5.7
so:
10.5 9.7 to.1
PrO,
02
0.0
0.5
02
0.0
0.0
0.0 0.0
2.6
0.6
0.0
0.0
0.0
0.0
0.0 29CaO,'7.8
8.3 _6J
JJ
J,L
32
J.9
Fr.ol"*_61
100.9 99.3 101.6 98.1
98.5
9.t
9,7 98,3

63
30.8
0.0
3.4
31.6
1.3
0.9
92
t3,7
0.9
0.0
7.e
99,7

fmlla&tlaW
t.ll

4.07
0.19 0.06 0.17
1.49
t.43 tA7 1.48 l.J9
0.32
0.45
126
025 t.t4
121 033 1.10 0.74022
o.o4-0.010'Uji-O20i
3.04
3.12 3.00 3.12 2.n

0.06
lJ6
0.98
0.44
3.M

2.97 3.M

1.00 1.66
0.9.6 l2t
0.91 0.91 0.93 0.48
0.AAji9,A----021
1.89 2,12 1.93 2.16

1.19
0.85

l:0
0.83

128 1.55 0J70.75 0.53 t.D

2.U

2.03

2.03 2.08 2.N

(on

6.41

5.86

.Cooposnioc(mpodsP

5.55 6.t2

5.57

t.90

PbO,wt.%
CaO
7aO
@2
GarOr
FerO.
dro.
A&o,
s03
Prot

0.98

7i
Ca

s

l.m

l.l7 0.98
0.04
1.53 t.39
0.q7 0.31
0.43 l.t0

1.00

As

1.00

1.00

Pb

AI

1.03

TABLE 4. ELECIRON.MICROPROBE COMPOSMONS OF Pb-Cn
PHOSP}IATE

029
2"40
0.12
0.13
2,94

s,69 5,12

10 Ga ealog@ of segnttite

Fig.1
4.3

Fig.5
2.2

Fig.6
PS3-A1

PS3-6

Fig.7
PS3-D

31.7
0.0
0.0
0.0
24.5
t0.7
t.7
1.1
5.5
!4.S
89.2

33.1
0.0
0.0
0.0
263
9.2
2.6
0.0
6.0
15.8
93.0

32.5
0.0
0.0
0.0
26.9
7.6
3.0
0.0
6.5
t5.2
9r.7

32,3
0.0
0.0
0.0
26.3
6.4
3.2
0.0
6.5
t4.2
88.9

33.2
0.0
0.0
0.0
27.4
7.O
2.6
0.8
5.5
t5.4
9r.9

32.5:

26.28
8.18
2.62
0.38
6.@
14.96
90.98
./s
98.34

[H,o]*
fomubfor
1.04
1.03
1.96
l.9l
0.98
0.80
0.36
924
3.13
3.t2
1.44
1.55
P
0.50
0.51
s
As9.0Zj--0,05O.02
2.06
2.Ot
5.95
5.74
oH
Pb
Ga
Fe
Al

Avg.

I4O

1.02
2.A
0.67
9A2
3.11
t.s2
0.s7

1.04
2.03
0.O
0.45
3.10
1.44
0.58

1.07
2,10
0.63
0.37
3.i0
1.5s
0.49

1.04
2.0O
0.73
932
3.10
l.sl
0.54

2.09
5.64

2.02
5.89

2.09
6.20

2.07
5.74

various zones in the gallobeudantite-bearinggrains(Tables2,3, 4), andtheimplicationsfor nomenclature,are discussedin later sections.
X-ray data
TABLE 3. ELECTRON.MCROPROBECOMPOSMONSOFGALLIAN HIDALGOITEAND BEIIDANTITE
Hidalgoite

Beudmtite

Fig. 3

Fig.2

Fig. 4

Fig.3

Fig. 5

7.2
33.5
0.0
0.9
15.2
11.1
18.9
9.0
0.2
0.3
E2.7

2.t
32.9
0.0
0.0
12.6
5.9
11.3
t7.5
11.0
0.0
0.0
91.2

5.7
32.7
0.0
0.5
18.3
2.6
10.8
17.5
9.7
0.5
0.0
92.6

7.0
31.6
0.0
0.0
t2.6
t9.7
1.5
24.6
6.5
0.9
0.0
93.4

2.0
29.6
0.0
0.2
lt.2
22.2
0.2
20.2
8.0
0.2
0.6
92.4

Pb

1.05

1.02

t.02

1.06

0.99

ZrL
Ga
Fe
Al
Ge

0.07
1.13
0.31
1.53
0.02
3.06

0.94
0.51

0.04
1.35
0.22
1.46

1.01
1.85
0.n

':

.--:

:

1.06
0.95

1.05
0.84

1.34
0.61

-

_q44

0.r0

PbO,wt.%
CaO
ZaO
Gqot
Fero,
Alros
Asrq
So,
PrO,
GeO,

As
s
P
(orD*

J.O

1.15
0.79
0.02
t.96
6.17

l.))

3.00

2.01
5.95

3.07

1.93
6.24

3.08

2.05
5.84

0.02
0.89
2.W
0.03
0.04
3.05
1.32
0.75
0.02
2.09
5.65

Debye-Scherrer X-ray patterns obtained with
114.6-mmcamerasand CoKcr radiation indicate thatthe compositionalvariations in the zoned crystals do
not have an extreme effect on the cell dimensions.
Although the X-ray powder pat0ernsof aggegatesof
the zoned crystals are not sharp relative ta, e.g., thepowder pattern of quartz, neither are they unusuallybroador diffirse, andthere areno signsof the multiplelines that would appear if solid solution radicallyshifted the cell dimensions.None qf the diffraction
pattemswas observedto havean 11 A diffraction line,
the presenceof whicl would indicate n 66ufling of
the c axis to -34 A" as occurs in some membersof the beudantitegroup and in the alunite - jarosite
family, with plumbojarositeperhapsthe best known
example.
The crystal structure of gallobeudantite wasdeterminedfrom a fragment extractedfrom the area
marked4.7 in Figure 1. The material extricatedfrom
area 4.7. which also included a small amount of
powder, gave a Gandolfi patlern that is spotty butotherwisematcheswell the patternof a bulk sampleas
listed in Table 5. Gallobeudantiteis rhombohedral,spacegroup R3m. T\e crystal-structuredetermination
gaveo7.zis1l), c r7.03(i) A.,vllo(t) A3.An energydispersion analysis of this single-crystal fragment
confirmedthe absenceof P.

1310

T1IE CANADIAN MINERALOGISTTABLE 5. REPRESENTATIVEX.RAY POWDERDATA FOR
I6

d*

90

s.85
5.00
3.59
3.52
3.038
2.920
2.851
2.513

l)

40
5
100
25
30
30
l0
I
40
l5
5
30
30

2.299
2.271
2231
1.948
t.797
1.759
1.715
1.693
1.678
1.646
1.519
t.497
r.4a9

TABLE 6. GALLOBETIDANTITE: STRUCTL'RE-DETERMINATION DATA

hkt
5.85
5.03
3.59
3.52
3.038
2923
2.846
2.514
2.330
2.300
2.271
2.231
2.060
r949
1.796
1.760
1.717
1.693
1.678
t.647
1.519
1.497
1.409
1.408
1.lmo

l0l
o12
110
104
113
2028
006*
024*
21lE
205
107*
t 163
214
303t
220,
208*
131
z'17*
I 1g*
1.0.10226'
0.2.10N

Idealfomula:
Spregroup:
Crystalsize:
Radiation:
Opelatingmnditions:p:Mia. aanmissioa
Mu. tnnsmission:

N Pbca3[(AsOJ,(SOJ]r(OH)6R3n(160)
0.12x 0.12x 0.06nm
Mo/gmphitemonocbmmator
50 kV/40 mA
28m'l
0.143
0.803

vx = Dr(lr, I - |r"lfnw r/tz,

a=7.us(4) A
c= t?.03Q)A't/=770(1)|:Z=4Totalrcfl.1290
f miqre496
i(in| 13.t%
Fo> 6c(F1416

r= F'?(r')l-rFinal i = 7.8%
FimlwR=6,7%

Normalized structure-factorstatistics, lP - tl =0.793, indicate an acentric space-group.The E-map
coordinateswere assiguedto appropriate scatlering
curves,Pb, Ga, As, S and six O atomsin R3z. Thisl)structuremodel refined to R = 8.0Vo.The equivalentt) I
5model in R3 refined to R = 10.0Vo,and n R3m, to
232
039N
1.400
R = 9.LVo.In the final least-squaresrefinement, the1.384
sites of all cations were refined with anisotropic1320
displacement-factors.The addition of an isofropic
1.285
extinction-correctiondid not improve the refinement.
*114.6-m Debye-Scherrer
In the final AF-synthesis,residual electron densities
cmerE CoI( X-mdiation.Lineswith
m rterisk rere usedfor theunit-cellrefinementindexedwith aremained, but none of these could be satisfactorily
7.184"c 17.077
4..
assigned to H atoms. The final positional anddisplacementparametersfor the gallobbudantite
structure are given in Table 7, and selectedbondlengths and angles, in Table 8. Observed andCrystal structure
calculatedstructure-factorshavebeensubmittedto the
Depository of Unpublished Data, CISTI, National
The fragment of gallobeudantiteused for the ResearchCouncil of Canada,Ottawa, CanadaKlA
collection of X-ray-diffraction intensity data is 0s2.
designated as CMNMI 81518. Single-crystal
Gallobeudantite is isostructural with corkite,precessionphotographsgave the space-groupchoices PbFer[(SO/,(Por]2(oH)6, (Giuseppetti & Tadini
R32 (155),R3m (1.60),andR3m (166) on the basisof 1987),with Ga replacingFe andAs replacingP within
systematicabsencesof reflections.Intensity datawere the crystal structure.The Pb site refines off the origin,collectedon a flrlly automatedNicolet R3n four-circle
diffiactometer. A set of. 22 reflectronswas used toorient the crystal and to refine the cell dimensions.
Threeasymmetricsetsof intensity datawere collected
up to 20 = 55o using a 0:20 scan-modeand variable
TABLE 7. GALLOBEUDANTITE:ATOMIC CoORDINATES
scanspeedsof 3 to 29olminute.Data pertinentto the
AND ISOTROPICDISPLACEMENTFAcToRs (A x l0)
colection of the intensitydataaregiven in Table 6. For
yzUeq
ATOM
x
the absorption correction, four intense diffractionmaxima in the range 13 to 50' 20 were chosenfor-0.014(0 0Pb0.020(4)4u(53)
ry diffraction-vector scansafter the method of NorthGa
0.ee78(D 0.4989(4) 0.4991(3) 154(9)et al. (L968). Structure determinationand structureAs000.6825(3) 84(10)refinementwere doneusing the SHELXTL (SheldrickS000.3011(8) 206Q3)
ol
000.579(1)200
1990)packageof computerprograms.The crystal's
02
000.394(l)200
irregular shape, precluding a good absorptiono3
0.7s2(3) 0.876(l) 0.7Dq,
159(35)correction,becamethe limiting factor in the structure
o40.216Q)
0.784Q) 0.%18(e) 288(44)problemrefinement. Thisin the data reduction is
oH1
0.45sQ)0.e0e(3) 0.803(t)260(42)or12 0.873(1) 0.746Q) 0.8660)
evident from a merging R of l3.l%o for the three
3q27)
asymmetricunits of reflection data.
I
5
l0
1
l0

GALLOBETJDANTITE"A NEW MINERAL SPECIES,TSIJMEB, NAMIBIATABLE 8. GALLOBEUDANTITE: SELECIED BOND
LENGTT{S(A) AND BOND ANGLESE)

Pb-o3
Pb-o3
Pb-o3
Pb-o4
Pb-04
Pb-o4
(Pb-o)Ga-O3Ga-O4Ga-OHlGB-OIi2(Ga-o)

Pb-O ICOSAHEDRON
2.6(3)
Pb-OH12.97(s)Pb-oHl2.69(4)
Pb-OHl2.58(4)
Pb-Orr2
2.96(4)
Pb-OH22.99(3)
Pb-OH2(PbOH)
Q.825>
ca-O OCTAHEDRON
1.99807)O3-o4
1.956(16)O3-oH11.9n(Dx2
O3-OH2
1.982Q)x2 O4-OH1
o4-o112oHl-oHl<r.962,oHl-OIt2
oHl-OH2
OH2-/JTI2

2.nQ)
2.uQ)
2.66Q)
2.73(2)2.71(2)2.e0(3)p.777t178.1(7)86.1(7)x2
95.7(6)x2/2.5(7)x2
85.7(6'1x2
86.1(6)177.9(6)x293.0(6)x 2
87.e(5)As-O TETRAI{EDRON

As-Ol
As-O3
(As-o)

r.76Q)o1-o3
1.68(2)x3 O3-o3(1.70)
(o-o)

s-o2
s-o4

S-OTETRAIIEDRON
1.58(3)o2-o4
106.7(l)x3
1.54(1)x3
O4-O4
112.2@x3(1.55)(o-o)(r0e.4)(s-o)

112.2(6)x3
106.6(6)x3(109.4)1 3 1I

as was found for the centric structure of beudantite(Szymardski1988). This shift within the polyhedron
is a result of the stereochemicallyinactive lone-pairelectronsassociatedwith Pb. an effect that has been
noted in the structureof severalminerals (Gice et al.
1991). As in corkite and beudantite"the Pb-O
polyhedronis an icosahedronwith the six Pb{ bondlengthsbeing longerthanthe six Pb-OH bond lengths:
gallobeudanlteZ.SZ Lversus 2.78 A, corkiteZ9Z A
versus 2.73 A (Giuseppetti&^ Tadini 1987), andbeudantite2.87 L versus2.80 A (Szymafski 1988).
The Ga site-occupancyrefines to an atomic scattering
powerof 24.8 elecffons*which compareswell with themicroproberesultsof 25.1elecffonsfor the combined
elementsG4 Al, Fe,7n, and Ge in the analysisof area
4.7 in Figure 1 (Table 2). The Ga polyhedron is aslightly distorted octahedronClable 8). The Ga polyhedra form (001) sheetsof corner-sharingpolyhedra(Frg. 8).The two tetrahedrasites[AsOal and [SOa]arealignedalong t0011(Fig. 9). The sitesarewell ordered,with site-occupancyrefinementsof 31.9Q) electons(As site)and 16.5(7)electrons(S site).Therefinements
are both within 2o of the ideal scatteringpower of As
and S, respectively.Similarly,orderingof the sitesis
demonstratedby^theaveragebondJengths,1.70A for
As-O and 1.55A for S-O, which are in keepingwith
other arsenatesand sulfates.It is the orderingof these
two tetrahedronsites that lowers the symmetry from
RSmtoR3m.

FIc. 8. A projection of the gallobeudantitestructurealong [@1] showing corner-sharing
layers of Ga octahedraaltemating with layers of (AsO) tetrahedra(dark shading),(SO, tetratredra(LBht shading)"and Pb atoms(filled circles).

13t2

THE CANADIAN MINERALOGIST

Ftc. 9. A projection of the gallobeudantitestructue along [110], showing layers ofcomer-sharingGa octahedra.The (AsO) tetrahedra(dark shading),(SO, tetrahedra(ight shading),andPb atoms(filled circle) are aliguedalong [001].

ternary system as shown in Figure 10 ignores
symmetry and cell-dimension variations such as
Beudantite has the ideal formula PbFe[(AsOJ, doubling of the c axis. The boundarybetweenFe3+(50112(0II)6, andthe stucture is rhombohedral,space dominantspecies(Frg. 10) and Al-dominantspecies
group R3n (Szymarlski 1988, Giuseppetti & Tadini (Fig. 12) is set at l:1; similarly, Ga-dominant1989). Although ordering of As and S lowers the species(Fig. 11) would have Ga > Fe3+or Ga > Al,symmetry of gallobeudantiteto R3rn, the effects of regardlessof the sum of Feh + Al.
order can be more pronounced,and may lead to adquUing of the c axis or to changesin symmetry(e.g., Solid solution
Cowgill et al. 1963, Radoslovich1982, Jambor &Dutrizac1983).To accommodatechangesin symmetry
The A position in the fornula of the algnite and the compositionalvariations,various subdivisions jarosite family may be filled by monovalentions suchof the alunite - jarosite family (which includes asK, Na, and(H3O),or by divalentions suchasPb,Ba,
beudantiteandcorkite) havebeenproposed(e.9.,Scott Sr, and Ca. Figure 10 shows the nomenclaturefor
1987,Nov6k et al. 1994).The systemofnomenclature the (XO) temary system in which Pb is dominant
applicable to this family is currently under review in the A position and Fe3+is dominantin B. The two(Jambor et al. 1995). Although the IMA-approved points plotted correspondto gallian beudantite(up to
nomenclatureis not consistetrtin all cases(Jambor L2.6 wlVo GqO3; Table 3). The analogousdiagram,et al. L996), in this paper we rigidly follow Scott's but with Ga > Fe3+, is shown in Figure 11.
(1987) MA-approved system for composition Compositionsof gallobeudantitefall mainly along orboundaries,despiteits limitations (Bhch et al. 1992, near the SOa- AsOajoin, extendingalong its lower
hing et al. 1995). Thus, tle simple Pb-dominant half and into the field of the Ga analogueof segnitile
NoNTENCLATUREGALLOBET]DANTITE.A NEW MINERAL SPECIES,TSUMEB, NAMIBIA

Pb.AI
unnamedPb-Fe
plumbojarosite(SOr),(so+)z(PO.)" (AsO4)2
kintor6iie PhiliPsbornite(AsOo),
segnitite

L313(Poa12
plumbogummite

Fto. 12. Nomenclaturefor the Al-dominant portion of theHc. 10. Nomenclaturefor the Feh-dominant portion of fle
Pb-xO4 membersof the alunite- jarosite family. Plotted
Pb-XO4membersof the alunite - jarosite family. Plotted
points correspondto compositionsin Table 3, but withpoints 2.0 and 7.0 are compositionsof Ga-rich beudantite
normalize<lto 2.00.
XOa
3).
Clable(Soa)2@ig. 11, Table 2). In the oppositedirection,the mostSOa-rich sample (cr3) is compositionally andmegascopicallydistinct, occurringon the specimenas
isolatedpatch about a millimeter ina cream-coloreddiameter.The patch is a granular aggregatein which
the grains are 5-10 pm across,are anhedral,brittle,
and lack cleavage.In transmittedlight, the grains arecolorlessand uniaxial positive,with ro 1.786(5)and
e 1.790(5)at 589 nm. Thus, the higher indices ofrefraction and change in optic sign distinguish thisphasefrom gallobeudantite,lessrich in SOoand POa,but no differences were observedin the 114.6-mm
X-ray powder-diffractionpattemsof the two fypes.
Solid solutioninvolving As-for-P substitutionin thezonedcrystalsis minimal in areasthat canbe analyzed
quantitativelywith confidence.Thus, Figure 11 showsclusteringof compositionseitheralongthe As-richjoinor the P-richjoin, with no As - P intermediatevalues.
The P-rich compositionscorrespondto the unnamed(Poa:12Ga analogueof corkite and the unnamedGa analogue(Asoa)2of kintoreite.
FIc. I 1. Compositionsof membersof the Pb--XOasystem,asSubstitutionsamong Ga, Fe, and Al are extensiveo
pointscorrespondin Figure 8, but with Ga > Feh. Plottedandany of these may predominatein B. Thus,
to compositions in Tables 2 and 4, but with XOanormalized to 2.00. Gallobeudantiteis the only named compositions extend from gallian beudantite(Fe3i > Ga > Al), to gallobeudantite(Ga > Fe3+> Al,mineral in the svstem.

t3t4T}IE CANADIANTABLE 9. DLDCTRON-MICROPROBECOMPOSnONS oF c€-ca ARSENATE
4.1

6

2

3.1

1.2

Avg. Forntul4I4O

PbO, wt%
CaO

8.3

1.5
9.0

2,8
8.5

2,6
7.7

2.8
8.5

2.42 Pb 0.07 ,'s
8.40 ca 0-97 ""

G€O:
GarO,
Ferq
Al.o,

12.4
23.5
2.4
3.0

ll.7
|.7
22.4
5.0
5.0
2.5

12,0
t2.0
23.8
3.1
2.6

12;7
25.0
2,9
1.5

t2.0
23.8
3.t
2.6

12.16 Ce 0.75
23.70 Gal.A -L>t
3.30 Fe 0.27
2,44 A 0.31

Aqot
s03
PrO,

38.8
1.0
0.0
91.8

38.0
0.7
0.0
90.8

37,1
0,7
0.0
90.6

19.0
0.7
02
92.3

37.1
0.7
0.0
90.6

38.00 As2.l4
0.76 s 0.06 A A
0.04 P 0.00
91.22
5.18

MINERALOGIST

predominancein Ca andAs, with Ga fte main elemgnt
in the B position.Contentsof Ge areup to 12.7wtvo
GeOr (Iable 9); although some substitution for As
would be expectedon the basis of their similar ionicradii (Bernstein 1985), it is evident that Ge# in the
beudantite-typeminerals substitutesfor the trivalentions in the B position. This Ca-rich mineral is inessencea Ca{a arsenatethat, if Ge were absent,
would correspondto the Ca analogueof the unnamed
Gaanalogueof segnitite(Figs.10, 11)or, moresimply,
to the Ga analogueof arsenocrandallite(Fig. 13). The
ideal end-memberformula of the latter catrbe written
as ^CaGa3H(AsOr2(OH)6.
Substitutionof Gea for
Gar+ is substantial, but is constrained by chargebalance limits so that the maximum Ge content
probably correspondsto Ca(Ga,Al,Fe)2Ge(AsO/2(OH)u. Table 9 shows that the composition of the
Tsumeb mineral reaches 75Vo of the probableallowablelimit of Ge substitution.

and Ga > Al > Fe3+),to gallianhidalgoite(Al > Ga >Fer+;Fig. 12).
In gallobeudantiteand its associatedminerals, theA positionis occupiedsolely by Pb (Iables 2,3,4);
however,someof tle crystalshavea narrow outennost
ACIiNOWLEDGEN4EIITS
zone, invariably less than 10 prn wide, in which Ca
predominatesin the A position. This mineral is
We thank CANMET personnel P. Carribre forunstableunder the electronbeam"and the narrowness assistancewith the X-ray powder studiesoandof the zonesandthe instability makeanalysesdfficult.
J.M Greer for preparation of the polished sections.
Nevertleless, the results (Iable 9) show a consistent Dr. F.C. Hawthorneof the Departmentof Geological
Sciences,University of Manitoba,kindly arrangedfor
the use of the four-circle diffractometer.The criticalreviews and editorial comments by A.C. Roberts,
W.D. Birch, A. Pring, and R.F. Martin are much
Ca-Al
appreciated.
huangite(so+)zRnrnnnNcrs
BERNSTEnI,L.R. (1985): Germanium geochemistryand
mineralogy.Geochim.Coyrnchim. Acta 49, 2409-2422.
(1986): Geology and mineralogy of the Apex
germanium-gallium mine, Washington County, Utah.
U.S.Geol. Surv..Bull. 1577.
BrRcH, W.D., PRsrc, A. & GArEHousE,B.M. (1992):
Segnitite, PbFqH(AsO)2(OtI)e, a new mineral in thelusungite group from Broken Hil1, New South Wales,
Australia.An. Mineral. 77. 656-659.
CowcrLL,V.M, HrncmlsoN, G.E.& JoEllstru,O. (1963):An
apparentlytriclinic dimorph of crandallitefrom a tropicalswampsedimentin El Pet6n,Guatemala.Am. MineraL S,
lr4-1153.

(AsO4)2
arsenocrandallite(Poa)2
crandallite

FIG. 13. Nomenclaturefor the Al-dominant portion of
the Ca-XOamembersof the alunite- jarosite family. The
equivalentFe3* analoguesare not known;"omporitionsin Table 9 conespond to the Ga analogue
of arsenocrandallite.

Durnzec, J.E. (1984): The behaviour ef impurities duringjarosite formation. In Hydrometallurgical Process
Fundamentals@.G. Bautista, ed.). Plenum Publ. Co.,New Yorh N.Y. (125-169).
JAMBoR,
J.L. & CnsNT.T. (1986):Host minerals
for the gallium-gerrnaninmores of the Apex mine, Utah.
Econ. Geol. 81. 946-950.

GALLOBEUDAIVTITE,A NEW MINERAL SPECIES,TSUMEB, NAMIBIA

C. (1987): Corkite,
GruseppsTn, G. & Telnlt,
PbFq(SO/@OJ(OII)6, its crystal structureand orderedarangementof the tenahedralcatrons.Neues Jahrb.
Mircral. Moratsh.7|-8L(1989): Beudartite: PbFe.(SOo)& (AsO/(OH)6, its crystal structure, tetrahedral site
disordering and scatteredPb distribution. NeuesJahrb.
Mi neral.Monntsh.,27-33.
Gmce, J.D., NrcKEL, E.H. & Gaulr, R.A. (1991):
Ashburtonite. a new bicarbonat€-silicatemineral from
Ashburton Downs, Western Australia: description andstructuredetermination.Am. Mineral. 76. 1701-1707.

1 3l 5

NovAK, F., Jft, J. & PRAcHAft,I. (1994): Classificationand
nomenclatureof alunite - jarosite and related mineralgjonps.V&tnik.eskgtogeol.tlstavu6g,5l-57.
A., BIRcH,W.D., DAwE,J., TAYIoR,M., Ds.;rsNs,M.
PRDIG,& WALENTA,K. (1995): Kintoreite, PbFe3(PO)t(OH,H2O)6,a new mineralof thejarosite- alunitefamily,
and lusungitediscredited.Mineral. Mag, 59, 143-148.
RADosLovIcH,E.W. (1982): Refinement of gorceixite
structure in Cm. Neues Jahrb. Mineral. Monatsh.,
446464.

Hoptm{s,J.L. (1985): Apex nine goesinto production. C/M
Bull. 7E(879),86-87.

Scorr, K.M. (1987):Solid solutionin, and classificationof,
gossan-derivedmembersof the alunite - jarosite family,
northwest Queensland,Australia. Am. Mineral. 72'
178-1,87.

Jeuron, J.L. & DurnIz^c, J.E. (1983): Beaverite plumbojarosite solid solutions. Can. Mineral 2l,101-113.

Srfl-DRIcK, G.M. (1990): SHELXTL, a Crystallographic
ComputingParkage (revision 4.1). SiemensAnalytical
Instruments,Inc., Madison,Wisconsin.

Kovara*rm., V.A. & RoBRrs, A.C. (1995):New
mineralnames.Am. Mineral.80. 630-635.

SzyMAI(sK,J.T. (1988): The crystal structureof beudantite,
Can Mineral' ?rt,923-932.
Pb(Fe,Al)3[(As,S)O4]2(OH)6.

PRrsEv, N.N. & Ronrnm, A.C. (1996): New
mineral narnes.Am. Mineral. 81, 249-254.
Nonrn, A.C.T., Hilr-ps, D.C. & Marrtsws, F.S. (1968):A
semi-empirical method of absorption coilwtior.. Acta
Crystallogr.424,351,-359.

ReceivedNovember21, 1995,revised manwcript accepted
August20, 1996.