Canadion Mineralogist
Vol. 30, pp.215-217 (1992)

FERRILOTHARMEYERITE.
A NEW CA_ZN_FE3*
HYDROXVLARSENATEFROM
TSUMEB,NAMIBIA1
H. GARY ANSELL ANDANDREW C. ROBERTS
GeologicalSuney of Canado,601Booth Street,Ottowa,OntarioKIA 0E8
PETE J. DUNN
Departmentof Mineral Sciences,
SmithsonionInstitution, Washington,D,C, 20560,U.S.A,
WILLIAM D. BIRCH
Deportmentof Mineralogyand Petrology,Museumof Victoria,Melbourne,Victoria3000,Australia
VALERIE E. ANSELL
22 Fairhill Crescent,Nepean,OntarioK2G 187
JOEL D. GRICE
Mineral Sciences
Section,CanadionMuseumof Nature, Ottawa,OntarioKIP 6P4ABSTRACT

Keywords: ferrilotharmeyerite, calcium zinc ferric ironhydroxyl arsenate,new mineral species,X-ray data,chemicalcomposition,Tsumebmine, Namibia.

Ferrilotharmeyerite occurs at the Tsumeb mine,Tsumeb, Namibia, as multiple subhedralcrystallitesand
as tabular to wedge-or lozenge-shaped
crystalsassociatedSouvernEwith tennanXite,scorodite,conichalcite,schneiderh6hnite
and beudantite.The mineral is monoclinic, spacegroup
A, Cm or A/m (diffraction aspectC*/*), with refinqd
La ferrilotharmeyerite,nouvelle espdcemindrale prounit-cell parametersa 8.9!!(7), b 6.236(2),c 7.390(3)A,venantde la mine Tsumeb, en Namibie, est pr6sentesous
Z = 2. forme de petits cristaux sub-idiomorphesou en tablettes
P 115.74(4)',V373.5(5)N, o:b;c 1.443:l:1.185,
The strongestsevenliner of the X-ray powder-diffraction ou en losanges,associdsi tennantite,scorodite,conichalpattern [d_ in4.95(70)(ll0), cite, schneiderhcihnite
et beudantite.Elle est monocliniND&k}] _are:3.398(100X202), 3.175(190)(ll2), 2.93_8(100)(201),que,. groupe spatial c2, cm ou a/m(aspect de2.823(70)(02r),2.702(70)(3t r), 2.544(l00tp2l). The crys- diffraction C*l*); les parambtres r6ticglaires ont 6tetallites are transparent to translucent, medium toaffi n6s:a 8.227(7), b 6.236(2),c 7.390(3)A\ P | | 5.74(4)",brownish yellow with an adamantineto greasylustre andV 3 7 3 . 5 ( 5N) , a : b : c 1 . u 9 3 : l : 1 . 1 8Z5 ,= 2 . L e s s e p t r a i e sa paleyellow streak.The mineralis brittle, with an uneven les plus intensesdu clich6 de diffraction (m6thode desfracture and a good [001]-cleavage.
D(meas.)4.25(5), poudres) ld en A(I)(hkl)J sonr: 4.95(70)(110),
D(calc,) 4.25 and 4,38 g/cm'for two empirical formulas.
2.938(100)(201),
3.398(l@X2@), 3.r75(l00X1la,Optically,the mineralis.biaxialpositive,with o 1.811(5), 2.823(70)(02r),2.702(70)(311),2.su(r0o)Q21).Lespetits
B 1.844(5),r I .88(l), 2V(meas.)85(5)', 2 Z(calc.) 89", X
cristaux sont transparentsir translucides,jaune moyen ir
approximatelyIl o, y | | b. Pleochroismis strong: Xjaune brunitre, avec un 6clat adamantin ou glas et une
olive green, Y pale green, Z colorless.Absorption is X
rayure jaune pdle. C'est un min6ral cassant dont la> f >> Z. lnclined dispersion of the optic axes is lracture est irr€gulidre; le clivage[001] est bon. Densit6
distinct, r > v. The ideal chemical formula is 4.25(5)(mesur6e),4.25et 4.38 (valeurscalcul6espour lesCa(Zn,Cu)(Fe3+,Zn)(AsO3OH)z(OH)s,derived fromdeux formulesempiriques).Biaxepositif, aveco l.8l l(5),electron-microprobeanalyses,water determination and p 1.844(5),y 1.88(l),2Z(mes.)85(5)",2V(calc.)
89", X
microchemicaltests.Ferrilotharmeyeriteis the ferric ironi peu prds ll a, y I I b. Le pl6ochroisme
est intense:X
analogueof lotharmeyerite,and is named to reflect this vert dlive, Yvert
pAle,Z incolore. L'absorption est X >relationship.
Y >> Z. La dispersion inclinde des axes optiques est
distincte, | ^> v. La formule chimique id6ale,Ca(Zn,CuXFe'*,Zn)(AsO3OH)z(OH):, est ddriv6e dedonn€es obtenues ir la microsonde dlectronique, desrGeological Survey of Canada contribution number
d6terminations de la teneur en H2O, et de tests
15690.
rnicrochimiques. Le ferrilotharmeyerite est I'analogue
225

226

THE CANADIAN MINERALOGIST

ferrifdrede la lotharmeyerite,
et son nom t6moignede
cetterelation.

7.38 A, I115.57', Thesedata are consistentwith
those reported for lotharmeyeriteby Kampf et al.
photography(1984).Because
upperJevelprecession(Traduitpar la R6daction) was impossibleand the X-ray powder patterns ofMots-cl6s:
ferrilotharmeyerite,
arsenatede calcium,zinc, the two mineralsare very similar, it was decidedto
fer ferrique hydroxyl6,nouvelleespbcemin€rale, index the powder pattern of ferrilotharmeyeriteby
donndes
aux rayonsX, composition
chimique,mine analogy with the powder data provided for
deTsumeb,Namibie.
lotharmeyeriteby Kampf et ql. (1984).Ferrilotharmeyerite crystals from specimenM38092 are also
INTRoDUCTIoN
unsuitablefor single-crystalprecessionstudy.
The X-ray powder-diffraction data for specimen
A new mineral, ferrilotharmeyerite, has been NMC 64573 (Table 1) were refined qsing twelve
identified on a specimen (NMC 64573) in the reflectionsbetween3.5M and 1.559 A for which
National Mineral Collection of the Geological unambiguousindexing was possible. The refined
Survey of Canada. The sample was collected in unit-cellparametersare:.a 8.997(7),b 6.?36Q),c
1983by John Innes, from the Tsumebmine (32 7.390(3)i\ I ttS.lq@)', V 373.5(5)N, a:b:clevel, W40 stope), Tsumeb, Namibia. The mineral 1.443:l:1.185,
with Z : 2. The'possiblespaceoccursas multiple subhedralcrystallites,averaging groups, also by analogy, are C2, Cm or C2/m
0.2 mm in length, with crudelyformed facesslightly (diffraction aspectC'r'lx').The cell parametersand
elongatein the b direction. The matrix appearsto cell volume are slightly lower than those reported
be feldspathicquartzite showingpervasivestaining by Kampf et al. (1984) for lotharmeyerite. Conby hematite. Ferrilotharmeyeriterims conichalcite tributing factors for the smaller unit cell are theand is in contact with tennantite. Large crystalsof
small but significant- differences in ieni! radii
scorodite and schneiderhdhnitealso occur on the berweenFe3* (0.64 g) and Mn3* (0.66^A), andspecimen.
berweenCu2* (0.72 A) and zn2^ (0.74 A).
After most of the data needed to define thespecieshad been obtained on the NMC specimen,
PHYSICAL AND OPTICAL PROPERTIES
additional ferrilotharmeyerite from the same
locality was found on a specimen of massive
Ferrilotharmeyerite on specimen NMC 64573
tennantite and calcite from the Museum ofVictoria, Melbourne, Australia (M38092). This occursas subhedralcrystals,averaging0.2 mm inspecimenhas a 7 x 7 cm crust of dark brown
TABLE I. X.RAY POWDER DATA FOR TERRIII'TIIARMTIERIItstabular beudantitecrystalsup to I mm across,andyellowish brown ferrilotharmeyeritecrystalsup tol(€lc)
hkl
/sL
d(m6)
hHd(elc.)/est.
d(tu6.)
about 0.6 mm in size. The water analysis for
ferrilotharmeyerite was obtained from this311
L010 2'069
56.66
001
30
6.66
specimenbecauseof the dearth of material on the400
LV6LM65494
110
4.95
70
NMC specimen.
, 1.988
ritrT
4.60
4.5930sr.983 I'
The mineral is the ferric iron analogue of
1.986 403
4.42zu4,4410lotharmeyerite(Dunn 1983,Kampf et al. 1984)and
1,E24 _;
1.9X
tt1
53544
203544is named to reflect this relationship. The mineral 100
z6. 1.850
3395
3398
1.U7 |' r s 4 730Mttz
and mineral name have been approved by the100
3.175 3.t'78
tn
3.118 0m
, tar2Commissionon New Minerals and Mineral Names. mr.8ll I'
201t08
u23L940
ml
2.938
I.M.A. The two specimensdescribedabove have 100'10D,
1n3
1J7Z
rc
2.p4
al
2.92i
been designatedcotype, and are the only known
tra
2.7V:ri' l72l
2.74
70
specimensof ferrilotharmeyerite.
1.701 |' 1 . 7 m50..;
X-RAY

CRYSTALLoGRAPHY

Precessionstudies were undertaken on several
fragmentsof ferrilotharmeyerite0.1 to 0.2 mm insize from NMC 64573,but in all casesorientation
photographs indicate that single-crystalmultiple
crystallitesare present.Even the smallestfragment
is composedof at leastfour individuals. Nevertheless,lr0land b" L20l' photographsofonefragment
clearly show monoclinic symmetry and gave
measuredunit-cell parameters:o 8.98, b 6.23, c2541/211\2/20
m972

lm

2544

50, 2.414
2.475 |' 2 . 4 7 1t0

2297

2.296

r0

2.26, zn6|' 2 2 6 0

r0, 2.2t92210 |'2204

003
402

20.2.154
2.147 |,
2.139

2Arrl

soten

1 6At"-"'[ 1.675312

20

1J89

1589

2430

1J59

1J5904020. 1J191518 |'
1509

42r.

30

. 1.469
1.468 |'1-468

23423

ffi

Z2l- I 14.6 m Debye-schere! powder @e&, Gr adiadotr Ni-filter (lGttro- in@miti6 estimated visually, valu6 of^d quoted h A- indsed with a 8.99'7,b 6136,c'1390 A-B 115.74"

1J4178 A)

FERRILOTHARMEYERITEFROM TSUMEB

227

size,in randomly orientedto subparallelaggregates bourne, Australia, provided the water analysisby
up to 3 mm in maximum dimension. The crystals CHN Analyzer. Microchemicaltestswere negative
are transparent, medium yellow to brownish for Fe2+and positivefor Fe3*.
yellow, with an adamantinelustre and a very pale
The empirical formula for NMC 64573,on theyellow streak. For M38092,the ferrilotharmeyerite basis of As2, is Cat.x5(Zn6.62Cuo.rr)rr.oo
Thecrystals are tabular to wedge- or lozenge-shaped, (Fe6.s7Zn6.1a)s1.61[AsO3.1e(OH)0.e0]2(OH)2.80.
averageabout 0.6 mm in size, and are commonly empirical formula for M38092, on the basisof As(Ca6.e2Pbs.65)p6.er(2n6.66Cu6.3a)p1.
2,
isintergrown with beudantite. These crystals are(OH)o.ss]z(OH)r.s0.
translucent,with a greasylustre and a pale yellow (Fe6.332n6.
154.le.er)gq.eIAsO:.arstreak. The mineral is brittle, with an uneven By analogy with lotharmeyerite, the idealized
fracture and a good {001} cleavage.The Mohs formula is Ca(Zn,Cu)(Fe3",ZnXAsojoH)2(oH)3.
hardnessis approximately3. Ferrilotharmeyeriteis Becauseproven casesof solid solution involving
not fluorescent under either long- or short-wave Cu2+ and Fe3+ are unknown, but Cu-Zn solid
ultraviolet light. The densityfor ferrilotharmeyerite solution has been reported in secondaryarsenatesfrom NMC &573, as determinedby the heavy-liquid and phosphates,such as philipsburgite (Peacorel
flotation techniqueusingClerici solution, is 4.25(5) ol. 1985)and kipushite (Piret el ai. 1985),all Cu
g/cm3. The calculatedvalue is 4.25 g/cm3 on the is assumedto substitute for Zn.
The compatibility indices of NMC 64573 ferbasis of the empirical formula for M38092, and4.38 g/cm3 on the basisof the empiricalformula rilotharmeyerite, on the basis of the Gladstonefor NMC 64573.
Dale relationship (Mandarino 1979)are 0.025 (forOptically, the mineral from NMC 64573 is the measureddensity)and 0.054(for the calculated
biaxial positive, with a l.8ll(5), I l.8M(5), tdensity), indicating a good to excellentagreement
1.88(l),2V(meas.)85(5)",as determinedin sodium betweenthe physical and chemicaldata.
light O 589nm), and2V(calc.)89o,Xapproximately parallel to a, and Y parallel to D. Pleochroism
ACKNOWLEDGEMENTS
is strong: X olive green, Y pale green,Z colorless.
Absorption is X > Y > > Z. Inclined dispersionof
The authors are grateful to Mr. David Sewell'
the optic axesis distinct,r>v.
Departmentof Geology,University of Melbourne,
for assistance with the electron-microprobe
analysesof specimenM38092, and to John M.
CHEMICAL COMPOSITION
Hughes, Robert F. Martin, and especially toFerrilotharmeyerite was analyzed by electron Anthony R. Kampf, for critical readings of themicroprobein two laboratories,at the Department manuscript.
of Geology, University of Melbourne, Australia,
REFERENCES
and the Smithsonian Institution, Washington.
Operating conditions, standards and analyticalresults are given in Table 2. A wavelength-disper- DuNN, P.J. (1983): Lotharmeyerite, a new mineralfrom Mapimi, Durango, Mexico. Mineral. Rec, 14,sion scanrevealedno elementsheavierthan oxygen
35-36.
other than those reported. The Australian Mineral
Development Laboratories (AMDEL) in Mel(1984):
Keupr, A.R., Sstcrrv, J.E. & RossvnN,G.R.
New data on lotharmeyerite. Mineral. Rec, 15,
223-226.

NMC 64573
C\rO fi.g
7aO
Fqq
CaO
PbO
AOr
MnO
MgO
AiO:
HzO
Total

2.9
15.8
M.\
12.1
n.d.
n.d.
tr.
r.
46.7
n.g.
91-6

5,75
13.94
13.96
10.86
213
0.13
Id.
n.d.
48.66
5.85'
10118

(3.82-7.9r)(1235-152s)(132G1s20)(1oJG1123)(0.673.47)(0.02-030)(4838-48.90)'E detemined by C-H-N anallei
tr. E ra@; ed. = not d€tected; &g. = not give!;
NMC 64573: SEMQ eledron miooprobe opeBted at 15 kV, 0.025 pA wple anen!
*ith standards: mangadre (Mn), eprite (C!), fluonpaiirc (Ca), zinc qide(Zn), olivenite (As), and honblende (Fe,Mg).
lvt,8F2:

JEOL eledron micoprobe opeoled at 15 kV, 0.02 pA wple
orenl
vitlt standards: mpper (Cu), wollotonite (Ca), zinc (Zn), Ntropyrite(Ar), hematite (Fe), orundum (Al), od galena (Pb). Valu$ in bBckeb
are the nngs.

MeNoanrNo, J.A. (1979): The Gladstone-Dalerelationship. III. Some generalapplications.Can.
Mineral. l7,7l-76.
Peecon, D,R., DuNr'.i,P,J., Rautr, R.A., SrunueN,
B.D. & ZrrurN, L.G. (1985):Philipsburgite,a newcopper zinc arsenate hydrate related to kipushite,from Montana. Can. Minerol. 23.255-258.
J. (1985):
Prnrr, P., DrLrers, M. & PIner-MEUNtER,
Occurrence and crystal structure of kipushite, a
new copper-zinc phosphate from Kipushi, Zaire.
Can. Mineral. 23, 35-42.
Received May 29, 1990, revised manuscript accepted
June 26, 1991.