Canadian Mineralogist
Vol. 23, pp. 50?-510(1985)
EHRLEITE,
A NEW CALCIUMBERYLLIUMZINC PHOSPHATEHYDRATE
FROM THE TIP TOP PEGMATITE,CUSTER,SOUTH DAKOTA
GEORGEW. ROBINSON,JOEL D. GRICEANDJERRYVAN VELTHUIZEN
Mineral ScientesDivision, National Museum of Natural Scienca,National Museumsof Canada,Ottawa, Ontario KIA 0M8
Lesonzeraiesde diffractionX lpsplus htensesdu clichE
depoudresontlc suivantes
Id enA (D@tDl l2ral?l)(ffi1l),
00), 6.58(30X1
01,01l), 5.r 0(20)
7:42Q0)(010),6.95(50X1
(102),4.31(40XU2)L3:89(A0Xl03)'
l3)' 3.43Q0)
3.46(20X1
(l2l), 3.l6(lm)Qr2,2rr,rr3)€.2.723(@)(123,023).
La denet 2.62(calcul€e),
avecduret6
sitdestde2.64(2)(mesur6e)
enlumibre
Mohs - 3Yz.L'ehrl9iten:estpasfluorescente
ultraviolette;
elleestsolubledansHCI froid dilu6d 2070.
Optiquement,
elleestbiaxepositive,aveca 1.556(2),
B
pourI = 589nm;2V(mesul9)
62 ,
1.560(l)andr 1.580(1)
49' (calcul6);
Xllc*, Yltb = l8o et Zlra : 9". Lesanaly(electrordque
sesparmicrosondes
etionique)ont donndBeO
7.9, CaO20.9,ZnO 14.8,P2O540.5,[H2O]15.9,total
10090(poids),d'oir la formuleempirique(poursixatomes
soit
de phosphore)Ca3.y2Bq
322n1e1P6O24.
15.9.28H2O,
Le nom honoreM.
id€alement
CaaBqZn2(PO+)e.9HzO.
type.
HowardEhrle,qui a ftouvdle sp6cimen
ABSTRACT
Ehrleite, a new mineral speciesfrom the Tip Top mine,
Custer,South Dakota, occursas vitreous, white to colorless,thick tabular crystalsup to 2 x 2 xl.l mm on a matrix
of beryl and quartz, with mitridatite, roscherite, hy"droxylherderite and goyazite-crandqllite. The crystalsshow three
pinacoids {100}, {010} and i00l} (assuming centrosymmetry),the habit form being chosenas {001}. Traces
of parting are observedon (001);the fracture is unevento
subconchoidal.Precessionphotogxaphsshow ehrleiteto be
triclinic and twinned by reflection on {001}, with possible
space-groups
Pl and Pl. The cell parametersare a7 .32Q),
b'7.54(t), c 2.a2(Q A, a 9r.19(44),p 99.94(82),7
98.64(47)', V 666.5A3 and Z= l.Jhe strongestelevenXray powder-diffracrionlines td in A (I) (hkl)l are t2.4te_0)
(00r), 742Q0)(010), 6.95(50)(100),
6.58(30)(l0l,0r l),
5. l0(20xr02),4.3I (40)(ll2), 3.!6_(20Xt03),
3.46(20X1
l3), Mots-clds:ehrldite,nouvelleespece
minerale,Dakotadu
3.43p0)(t2t),3.t6[m)Qr2,2tl,l 13)and 2.723(@)On,aX).
Sud,b6ryllium,pegmatite.
The densityis 2.64Q) (mas.) and1A g/cmt (calc.),with
Mohs hardness3 72.Ehrleite is non-fluorescentin ultravioler
radiation and soluble in cold, 20Vo}JCl.It is optically biaxINTRoDUc'IIoN
ial positive,with a 1.556(2),B I .560(l)and 7 1.580(l)for
I = 589 nm; 2Z(meas)62',2V(aLc) 49o:X\c*, Yltb =
The Tip Top mine, in the Black Hills of South
l8o and Zlta = 9".Its composition,determinedby elecDakota,
is famousfor the wide varietyof phosphate
tron and ion microprobes,givesBeO 7.9, CaO 20.9, ZnO
14.8,P2Oj 40.5,[H2O] 15.9,total 100.0wt.9o, and yields minerals it has produced. During the winter of
l98l-1982, mining operations in the outerthe empiricalformula Ca3.e2Bq
32Zn1.s1P
6O2a.6.9,28H2O,
basedon six P atoms, or, ideally, [email protected]. intermediatezoneresultedin the discoveryof an unuThe namehonors Mr. Howard Ehrle, who found the type sual assemblageof secondaryphosphateminerals.
specimen.
The subsequentcollection and dispersalof specimens
immediately rousedthe intere$tof botl amateur and
professionalmineralogists,and has culminatedin the
discoveryof five new mineral species:fransoletite
(Peacor et ol. 1983), tinsleyite (Dunn e/ al. 1984),
(Griceet a|.1985), ehrleite(this study)and
tiptopite
SoMMAIRE
an unnamedmineral presentlyunder investigation.
L'ehrl6ite, nouvelleespdcemindraleprovenant de la mine In addition, the specimensof the associatedmineTip Top a Custer(Dakota du Sud), setrouve, sur b6ryl et rals montgomeryite,robertsiteand englishiteconsquartz, en cristaux de facies tabulaire et d'€clat vitreux, titute some of the finest known of those species
blancsi incolores,atteignant2 x 2 x 0.1 mm, associds (Dunn e/ al. 1983,Campbell 1984).
d mitridatite, roschdrite, hydroxyl-herddrite et goy{rsiteEhrleite CaaBqZn2@O)6.9H2O is a very rare
crandallite. Les cristaux, dans l'hypothbse d'une centrosy- species;to date, only two specimensare known. The
m6trie, prdsententtrois parall6loidres, {100}, {010} et name honors Mr. Howard Ehrle, of Miles City,
{001} le plan d'aplatissement6tant choisi comme(001),'sui- Montana, who found the holotype specimenand
vant lequel on observe aussi des plans de separation. La
submitted it to the National Museum of Natural
fracture est irregufdre ou subconchoi'dale.Les clich€s de
pr6celsion confirment la sym6trie triclinique, groupe spa- Sciencesfor identification. Both the new mineral and
tial Pl ou Pl , et un maclagepar r6flexion sur {00t}, I,Ss the name have been approved by the Commission
on New Minerals and Mineral Names, IMA. The
plans r6ticulairessont a 7.32(7), b 7.54(l), c n.a2@) A,
q 91.19(44),P 99.94 (82), 198.64(47)', V 6ffi5 Ls et holotype specimenis preservedin the collection of
Z=1.
the National Museum of Natural Sciences.Ottawa
Keywords: shrleite, new mineral species,South Dakota,
phosphate,beryllium, pegmatite.
507
508
THE CANADIAN MINERALOGIST
(NMNS #49289),A secondspecimen,the cotype,is
in the Museum of Geology, South Dakota School
of Mines and Technology, Rapid City (SDSM&T
#29s8).
to2 x 2 x 0.1 millimetresand as aggregate$
of randomly orientedcrystalssomewhatresemblingclear,
tabular barite. Upon magnification, however,their
true morphology becomesevident (Figs. 1, 2). The
APPEARANCE, PHYSICAL AND
Oprrcar Pnopsnrrcs
Ehrleiteoccursas individual tabular crystalsup
za
Frc. l. Tabular crystalsof ehrleite.SEM image;width of
field of view is 130 pm.
Ftc.3. Stereographicprojection of optical and crystalloeraphic elementsof ehrleite,
TABIA
00!.
010
t00
Ior
orl
011
qo2
1L0
11r
io?
0L2
012
lrz
rr1
II2
LLz
io:
020
2ot
200
113
L2L
xr3
i2I
201
2L2
ZrI
ir3
oo4
210
L22
22t
014
].].a
i23
022
2L3
123
204
2L2
030
o3I
Frc.2. Twinned tabular crystalsof ehrleite. SEM image;
width of field of view is 170 lm.
1.
X-RAY
POIIDER-DII'FRACTION
L2.22
7.44
7.r2
6 . 6 9I
e.sol
6.221
e.:-rl
5.60
5.30
s.11
4.84
4.61
4.36
4.24\
4.09t
3.93
3.04
3.71
3.601
3.s6,
3.47
3.43
3,3611
r.:ssf
3.267
3.200)
3.L79,
:. ra:j
3.055)
3.033)
s.oosl
z.i93l
2.779>
z.ttol
2.127\
2.683t
2.660
2.6L4
2.5s4\
2.5491
2.481
2.4s4
DATA FOR EERLEIIrE
2.4 4L
2.323
6. 18
2.130
2.086
2.O44
2.O34
r.981
r.932
1.903
1.8?8
4.42
4.59
{. L6
1.917
1.793
L.767
1.730
L.66I
1.648
3.86
3.46
3.286
1,540
3.16I
1.502
L.479
t.45L
1.431
3.014
1.366
1.348
2-662
2
2.459
1
C u - & 6E a d l a t l o n ,
1.54178L.
C6l1 Parueters:
b 7.54(L't, a 72.421414, 6 9L.214r, B 99.9(8),
L.244
a ?.32(71,
y 98.5(5)"
EHRLEITE, A NEW Ca-Be-Zn PHOSPHATE HYDRATE FROM soUTH DAKOTA
crystals are triclinic and twinned on {001}, with
observedforms {100}, {010} and {001}. Ehrleiteis
milky white to colorlessand transparent,with a white
streak. It has a vitreous lustre, a Mohs hardnessof
-3Y2, an unevento subconchoidalfracture and au
apparent pafting on (001). It is nonfluorescentin
ultraviolet radiation. The averagemeasureddensity,
as determinedby flotation in a bromoform-butyl
alcohol solution, is2.64(2) g/cm3, which compares
favorably to the calculateddensity of 2.62 g/cm3
basedon six phosphorusatoms. It is readily soluble
in cold, ?.00/o
HCL
All measurementsof optical propertiesweremade
in sodiumlight 6= 539nt1). Ehrleiteis biaxial positive; its indicesof refractionareo 1.556(2),B I .560(l)
and "y 1.580(1);2Z (measured)62", 2V (calculxed)
49'. The optical orientation is shown in Figure 3,
with Xllc*, Yttb : 18" and Zlto : 9o,
509
dardized on copper. Wavelength-dispersiondata
were obtained and correctedby computerprogram
(Tracor-Northern ZAF, version ll, l98l). Except
for traces of Mg and Al, no other elementswith
atomic numbers greater than nine were found.
Beryllium was analyzedby ion probe, and water
calculated by difference. It is regrettable that lack
of sufficient sample precluded a water determination by any conventional means; the presenceof
hydrogenwas confirmed by ion probe, though the
amount could not be quantified.
The resultingcompositeanalysisgaveBeO7.9(9),
CaO 20.9Q), ZnO 14.8Q),P2Oj 40.5(0),H2O 15.9,
total 100.0wt.Vo. Basedon six phosphorusatoms,
the empiricalformula is Ca3.eBq.r2Zq.srPe.oOz.rs.
9.28H2Oor, ideally, CaaBqZn2(POa)6.9H2O.The
observedexcessB€ is probably best explainedby the
relatively high rangeof error associatd with the analytical techniqueemployed.
X-RAY Cnysratlocnapny
Using the observeddensity and the constantsof
Mandarino (198l), the Gladstone-Dalecalculations
Six crystalsof ehrleitewerechosenfor precession yield K. 0.2141andKc0.2l36, with a compatibility
studies,and all were found to be twinned by reflec- index l-(Kr/K") of 0.0023, indicating superior
tion on {001}. The zero- and upper-level a-axis agreementbetween the physical and chemical data
precessionphotographsrevealthe effect of this twin- (Mandarino 1979).
ning on the reciprocal lattice; 1) there is a mirror
plane perpendicularto c*;2) the observedpe$odiPanacsNEsrs AND OcCURRENCE
city along c* yields a pseudocellwith c -Za A and
a twin index of six, and 3) the twin obliquity is zero,
The Tip Top mine is locatedjust southwestof the
and there is no reciprocaliattice row perpendicular centreof Sec. 8, T3S, R4E, approximately8.5 km
to the c* axis. Thus the twin lattice is closeto, but southwestof Custer, South Dakota. As previously
not actually monoclinic. When the crystal is viewed mentioned,mining activity at the time the two known
with a polarizingmicroscope,it can be seenthat the ehrleite specimenswere discoveredwas confined to
compositionplane (001) centrally divides the crys- the outer-intermediatezone of the pegmatite.This
tal into two equal halves.This is also evidenton the zone is characterizedby large crystalsof perthitic
SEM photograph (Fig. 2).
microcline,triphylite, quartz and muscovite.AccesThe unit-cell dimensionswere refined from X-ray sory minerals include beryl, albite, fluorapatite,
powder-diffraction data obtained using a 114.6-mm- elbaite and columbite-tantalite (Grice et ol. 1985),
diameter Debye-Scherrercamerawith CuKa radia- Secondaryphosphatemineralization occurred along
tion (Table 1). The refined cell-parameters^and fracturesin the beryl, quartz and perthite, but subvolume are o 7.32Q), b 7.54(l), c 12.42(4)A, q sequentmining hasremovedvirtually all of this area.
9"1^.19(44),
Neither of the ehrleite specimenswere collected
P 99.94(82),7 98.64(47)"and V:666.5
Ar, with Z : l. T:herather large standard deviations in place; therefore, their exact geologicalrelationare a result of difficulties in indexing the powder pat- ship to the pegmatite as a whole is unknown.
tern of a triclinic cell. Only 12 reflectionscould be Nevertheless,the paragenesisof speciespresenton
indexeduniquely with the aid of precessionphoto- eachspecimenmay be described.The associatedspegraphs.
cies on each specimenis somewhat distinci. The
matrix of specimenI (NMNS #49289)is intergrown
CrreN4IcAJCOMPoSITION
beryl and qtJartz. The first phosphates to have
formed are olive greenmitridatite and orange-brown
Becauseof the particular elementsfound in ehrleite roscherite, followed by clear, botryoidal hydroxyland the small amount available for analysis, it was herderite;white, micaceousgoyazite-crandallite;and
necessaryto employ a combination of anlytical tech- ehrleite.The matrix of specimen2 (SDSM & T #2958)
niquesto determineits composition. Analysis for Ca, consistsof beryl only. Rusty orange,botryoidal apaP and Zn was done by an ARL - SEMQ electron tite appearsto be the frst phosphateto have formed,
microprobeusing syntheticCarPrO, and sphalerite followed by black, globular, amorphous Mn
asstandards.The microprobe was operatedat 15 kV oxide(s);beige-white,powdery roscherite;clear, radiand a beam current of 100 x l0-e amperes,stan- ating aggregatesof pardscholzite; and ehrleite.
510
THE CANADIAN MINERALOGIST
AcKNowLEDGEMENTS
Gnrce, J.D., Ppecon, D.R., RosrNsox,G.W., VeN
Vslruurzsr.r, J., RosBnrs,W.L., Cavrnrlr, T.J. &
Dmw P.J. (1985): Tiptopite (Li,K,Na,Ca,[)g
Be6(PO/6OH)4, o n€w mineral species from the
Black Hills, South Dakota. Can. Mineral.23,4346.
We thank Mr. Howard Ehrle and Mr. W.L.
Robertsfor generouslyproviding the specimensfor
this study. We are also indebted to Mr. I. Wainwright at the Canadian Conservation Institute, for
access
to the SEM, and to Dr. P.J. Dunn and Profes- Mewoanno, J.A. (1979):The Gladstone-Dale relationsor J.D.H. Donnay for their many helpful discusship. III. Some general applications. Can Mineral.
17,7l-76,
sions.
REFERENCES
Cavpgpr.r.,T.J. (1984): Phosphate Mineralogy of the
Tip Top Pegmotite, Custer, South Dakota. M.Sc.
thesis, South Dakota School of Mines and Technology, Rapid City, S.D.
DuNN, P.J., Ronnnrs, W.L., Caurnrll, T.J. &
LeevsNs, P.B. (1983): Red montgomeryite and
associatedminerals from the Tip Top pegmatite with
notes on kingsmountite and calcioferrite. Mineral.
Record 14, 195-198.
Rousr, R.C., Carrtpsell, T.J. & Rossnrs,
W.L. (1984): Tinsleyite, the aluminum analogue of
leucophosphite, from the Tip Top pegmatite in
South Dakota. Amer. Mineral. 69. 37+376,
(1981): The Gladstone-Dale relationship. IV.
The compatibility concept and its application. Can.
Mineral. 19, 441-450.
Precon, D.R., Dutr.l, P.J., Rosenrs,W.L., Cavearll,
T.J. & NewsuRv,D. (1983):Fransoletite, a new calcium beryllium phosphate from the Tip Top peematite, Custer, South Dakota. Bull. Mindral, 106,
499-s03.
ReceivedFebruary6, 1984,revisedmanuscriptaccepted
January18, 1985,