the Scanned PDF - Mineralogical Society of America

the Scanned PDF - Mineralogical Society of America

American Mineralogi,st
Vol. 57, pp. 364 367 <1972)
ELYITE, BASIC LEAD-COPPER SULFATE, A NEW
MINERAL FROM NEVADA
,SrnNnv
A. Wrr,r,reus,PhelpsDodge Corporation,
D ouglas, Ari,zona 85607
ABSTRACT
Elyite, Pbacu(sor(ol1)s, was found at ward, Nevada where it occurs in voids
in massive sulfides showing incipient oxidation to supergenegalena, serpierite, and
langite.
The color is violet with a pale streak; f/ : 2, G^.^" - 6r P"urc.: 6.321gcm'-8'
Good cleavage on {001}, and crystals are sectile. Crystals are monoclinic 2/m and
show: a {100},c {001}, d [501], ft ll2ol,I {310}, and h {zlll. Twinning in {001|
common.a : 1.990,F : 1.993,t : 1.994.
Cell dimensions are o : L4.2484',b : 5.768, c : 7.3O9; F : lOO"26', P2l/a.
Z : 2. The strongestlines (in A) are 7.189(99), 6.999( 100), 4.456(25), 3.627 (27)'
3.341(31), 3.136(32), 3.081(29), 3.M7 (30), 2.995(73), and 2.884(37).
Chemical analyses gave (averaged and calculated to IOO/): PbO 79.40/s, CtrQ
7.76Vo,SOt 6.90/6, and]JrO 5.9370which leads to PbnCu(SOn)(OH)"
OccunnnNcn
Elyite was found in 1964 during mining operations by Silver King
Mines, Inc. at Ward, Nevada. The mineral was only observed in the
Caroline tunnel, and these workings have since been obliterated by
open-pit mining.
The sulfide ores occurring in the tunnel were locally massive chalcopyrite, sphalerite, galena, and pyrite with only minor amounts of
euhedral qvartz, as gangue. In those areas showing incipient oxidation,
elyite was found with langite (Williams, 1964), serpierite, and super-
genegalena.Voids in the sulfide massestend to be partly filled with
earthy browh to black galena,and elyite crystalsoccur in this earthy
material. Langite and serpierite are later. In specimensexhibiting
later minerals such as brochantite or cerussitethe elyite had disappeared.
of elyite were preserved,and the total supply
Only a few specimens
doubtlessis lessthan 50 milligrams. A specimenhas been deposited
at the British Museum(Natural History).
Prrvsrcer, Pnoppnrrps
Elyite is a lovely violet color (Royal Horticultural Society,83'B,
Munsell 5P 4/10) with a pale violet to white streak.The luster is silky
in fibrouscrystal groups.The hardnesson Mohs' scaleis 2 and crystals
was not observedin either long or short wave
are sectile.Fluorescence
lenglh U. V. Cleavageon {001} is goodbut difficultto observeowingto
ffi4
ELYITE
365
T A B L EI
CHEMICAL
N A L Y S EOSF E L Y I T E
Pb0
81.9
Cu0
8 .0 3
s0-
6.45
5
8r.4
7.94
H^0
.366
81.65
79.40
79.40
. r00
7.98
7.75
7.07
.089
7,10
5.90
7.12
5.93
6.41
2?q
A
I
l 0 2 .8 3
l,
9 9. 9 9
| 0 0. 0 0
2
_ a n a l y s e sp e r f o r m e d b y R . F . S y m e s o n e l e c t r o n
(Natural llistory)
3
g r a v i m e t r i c a n a l y s i s b y J . A . A i l e n ( p h e l p s D o d g eC o r p o r a t i o n ) o n 8 2 u g ,
loss occurred between 550'C and 720.C
4
rat ios
5
averageof analyses I,2,
6
averageanalysis recalculated to l0OZ
7
P b t | c u( s o 4 ) ( o H )
8
probe at British
Museum
J
the minutenessof crysta,lswhich never exceed0.15mm in length.The
crystals are prismabicto fibrous and occur as radiating sprays or
tufts, sometimesmatted, which are perched upon or embeddedin
earthy galena.The specificgravity was estimatedas aboui 6 from.the
rate of settling in glycerine using more accuratrelyknown minerals
as bracketingstandards.
CHplrrsrny
Microchemicaltests upon elyite showedcopper,lead, and sulfate.
Tests for halogenswere negative. Qualitative analysis by electron
probe verified thesefindingsand duplicateanalysesfor Cu, Pb, and S
were then performed using linarite, anglesite,lead and copper as
standards.The results of theseanlysesare shown in Table 1.
Water was determinedgravimetricallywith the lossoccurringabove
550o C, and its presenceverified in the closedtube.
The results of the analysesagreewell with the theoreticalformula
PbaOu('SO+)(OH)s
and the "empirical" cell constants(usingthe cal(SO+)
culateddensity)arePb+.ooCut.to
os, (OH),.n0.
In dilute (1 : 7) cold nitric acid elyite crystals quickly turn to a
flocky white mass;in cold 1:5 HCI they are filmed with white PbCl2.
They are insolublein cold or hot water,
SIDNEY A. WILLIAMS
Cnvsrer,r,ocnAPHY
Despite the minutenessof the crystals some gave relatively good
goniometric data and a number of forms were found. The crystais are
invariably elongateon [010]and tabular on c, {001}, the dominant form.
Otherformsfoundare:o{100},d{501},/c[120],,{310},and h{211}.A
typical crystal is shownin Figure 1. Mirror twinning in {0C1} is common
and non-repetitive; never were more than two individuals found in
twinned position. Single crystals could be readily separatedfor X-ray
study, for the twin plane is 4,plane of easyparting.
X-Rev ANer,vsrs
A single crystal 0.13 mm long was used for rotation and Weissenburg exposures.
Cell constantsobtainedwereusedto index the powder
pattern, and their refinement was carried on frorn powder data using
b =
a,program written by F. B. Millett. The results are a = 14.248Fr,
5.768,c: 7.309(all -t- 0.002A)I F : l@o2V ! 7'. The spacegroup
is P21/a, and the calculateddensity is 6.321 gcm-s for Z = 2. The
indexedpowder data are presentedin Table 2.
Oprrcs
Elyite is transparent in transmitted light and pleochroicin violet
wilh Z > Y > X. The indicesof refraction are c = 1.990'B = 1.993,
y =.L.994 (all +- 0.001)in Na (D) light, and 2V'is76o aI'480,68o
at 550,66o at 580,and 64" al 630 nm. The optic orientationis Y : b,
x r\ c (in p) - 35o, 42", 45o, 49" at 480, 530, 580, and 630 nm respectively. Dispersion is quite noticeable in interferencefigures.
DrscussroN
Elyite is not likely to be confusedwith minerals of similar composition; it differs markedly from linarite in physical properties.No
mineral with the same color is similar chemically.
The mineral is named for John Ely, an important figure in the
early mining history of easternNevada (Ashbaugh,1963).
The mineral and mineral name have been approvedby the Committee on New Minerals and New Mineral Names,IMA.
ELYITE
367
TABLE2
X - R A Y P O I . / D EDRA T AF O RE L Y I T E
V-fi ltered,
!/Lo
CrKq radiation;
1l 4 m m . W il s o n C a r e r a
!(ots.)n
!(calc.)i
bkl
!/Lo
d(obs.)e !(carc.)A
hkl
qq
7. I894
7 .t 8 8
001
f8
2.772
2.772
\02
100
6.999
7. 0 0 6
200
It
2.663
lt
\.614
4.617
2.663
2.667
201
t2i
22o
4'+se
+,qfi
2t0
t7
2.624
2.628
2.624
302
4lI
2l
3.621
3.628
301
20
2,435
17
) .400
3.40t
2.436
2.434
401
loJ
soi
3l
3.341
t3
2.335
2.335
l02
600
5,559
?)
3.136
3.135
302
t1
2.243
2.243
2.24\
sti
I 13
,o
3.081
1.081
112
3
2.194
2,200
421
3C
3.o47
3.O50
0t2
a2
5
2.166
t
2.994
410
2.169
2.i65
403
6|o
2t2
9
2 . A 11
2.009
2 . 0r0
2.ot5
6t2
503
213
ooE
I
2.97o
)
t2
2.930
2.930
4il
2.884
2 .8 8 4
:t20
9AA
plus ten additional
t i nes to I .497i
|/ l o
d(ots.)i
a) precision
o f r e a s u r eyda l u e s! o . o o S a
i t 7 i d e c r e a s i nt g
o r o , o o z ia t z i ,
basedon fiye reasurements
of onefi lm.
Acrrownncnnarwrs
r am grateful to R. F. svmes (British Museum) and J. A. A[en (phelps
Dodge corporation) for performing chemical analyses. F. B. Millett (phelps
Dodge Corporation) provided invaluable aid by writing a refinement program.
Rnnonnwcns
AsHneucu, D. (1963) Neuad,ols Turbulent yesterday
a Study in Ghost
Touns. Western Lore Press,Los Angeles.
Wrr,r,rerrs,S. A. (1964)A new occurrenceof langite. Am.er.Mineral.+g,Ll4B_lL4S.