MINERALOGICAL
782
NOTES
HurroN, C. O. (1956) Manganpyrosmalite, bustamite and ferroan johannsenite from
Broken Hill, New South Wales. Arn. Minetal.4l' 581-591.
Parecrr, C. (1937) The minerals of Franklin and Sterling Hill, N. J. U' S' Geol,.Surtt.
ProJ. Paper 18O,75-79
Scn.tr-rrn, W. T. (1938) Johannsenite, a new manganesepyroxene. Am. Mineral' 23r 575582.
Scnr.lvrn.tro, G. (1953) Sulla johannsenite dei giacimento a silicati manganesiferi del
Monte Civillino. Rend..Soc.Mineral.Ital.9,21O 218.
Yonnn, H. S. alln T. G. Sanau,l (1957) Olivine *-ray determinative curve. Am. Mineral.
42,475-491.
THE AMERICAN MINERALOGIST,VOL 50, MAY_JUNE, 1965
CRYSTALLOGRAPHIC
DATA
FOR RARE-EARTH
PART II
ALUMINUM
GARNETS:
C. B. RuerNSrErNAND R. L. BenNs, Bell Telephone
Laboratories,Inc., Murray Hill, l{ew Jersey.
The rare-earth aluminum garnets may be representedby the general
where R representsthe rare-earthion. The crystalloformula RaAIzAlsOrz
graphic properties of the rare-earth aluminum garnets from terbium to
thulium in the periodic table were reported by Rubinstein and Barns
(1964). This note presentsthe indexed r-ray powder data and index of
refraction for gadolinium, ytterbium and lutetium aluminum garnets
which will hereafter be referred to as GdAlG, YbAIG and LuAlG. In
addition, the growth habit of YbAIG is reported.
All the crystalsusedin this studl- were grown by a techniquediscussed
by Van Uitert et al.(1965). The crystalsvaried in sizefrom fractions of a
The total impurity conmillimeter to a full centimeter in cross-section.
per cent. The powder
be
0.1
to
crystals
is
estimated
in
the
centration
Norelco
with
a
Straumanis-Type
photographs
were
taken
diffraction
filter.
Ni
and
an
radiation
using
CuKa
114.6
mm
diameter
of
camera
given
are
so
obtained
The
data
film
shrinkage.
were
made
for
Corrections
1.
Table
in
The lattice parameters used to calculate the spacings reported in
Table 1 are given in Table 2. The color, r-ray density and index of refraction are also given in Table 2. For convenience,our previously reported lattice parameters,r-ray densitiesand colorsare also included in
Table 2. The refractive indices were determined with a Rayner refractometer equippedwith a sphaleriteprism. The indicespreviously reported by
Rubinstein and Barns (1964) were redeterminedby this, more accurate,
method. A conservativeestimate of the error for the lattice parameter
gives 3o limits of + 0.003 A and an estimateof the probable error for the
index is +0.001.
Iablc
I,
x-Rry Pordcr D.tr
hkt
I
vlsual
2lt
220
32r
4oo
4?o
\zz
9
l.
qtl
Sample
C d AG
I
d (A)
d (^)
c al c d
obgd
Y b AG
l
d (a)
d (a)
calcd
obld
l}.s3a
\.86s
4.2f7
3.t8\
2.980
2.663
2,430
2. l ?\
t.933
r.758
1.7f8
1.65t
1, 6 2 0
L592
1,513
1.49o
I.332
1.300
r.285
t.270
l. lo8
r.062
t.o54
.9682
.8996
.8890
.6t9t
.tl t6
. ?866
2
3
I
3
|
|
3
I
2
t
|
3
2
r
r
4,944
4.252
3.237
3.028
2. 708
?.\72
2,211
r.964
t,785
I .749
t.679
| .648
1.518
I,53S
1.5t4
1.354
I .321
1.306
r.291
1.124
L079
I .070
,9823
.9t29
.9027
,8318
,821rc
,7985
|
I
.7850
.7753
. 7E50
. 7753
E
6
3
4
5
3
ll
8\o
e\z
9 2 1 ,7 6 1, 6 5 5
66\
t04o,864
I tzt,lo5t,963
880
t?2?,lo6l{'
1244
1260,to8l|
I 44O,| 262
l\42,1?o6,rolo4
1521,!s3,r365
I I l03,109?
rs32,.]Js6
t z l o o ,t 2 8 6
Aluninun Grrnets, CuKa (l
4.277
3.?30
3.O20
2.697
2.464
2.207
t,959
1.783
I .745
r.6?6
I .646
t.6t5
t.537
t.sil
l.3sr
| .3t9
1.305
1.29r
t.l2r
1.079
l.o7t
.982\
. 9 13 2
.9033
.83t8
.8239
.7985
7
6
ro
\
5 tt , 5 3 2
63t
\\4
640
721,633,552
6\a
732,651
goo
Taeln
for Rlrc-E.rth
'
\.8?o
\,2!6
3.r88
2,9A2
2.66?
z. \35
2. I 78
1.935
1.759
t.l?2
t.514
1, 6 2 3
L59\
1,515
l.qgt
|.331+
1.302
r.286
t.?7?
l. lo8
1.063
r.os4
.9675
.8992
.8E91
.8t93
. E rr ?
.7865
1.5\l8A)
R.dlation.
L u AG
l
d (A)
d (a)
c
alcd
ob3d
4.856 \.863
4.205 \.212
3.175 3.l8ll
2,958 ?.978
2.659 2.664
2.\32
2.\29
3, I 7s
?.l72
1.930 L932
1.758 1,756
1,.719 l.?19
1.651 1.65?
1. 6 2 0
1, 6 2 1
I .591 1.s92
1.513
l.5ll
1.488 l.l+89
I.330
|,332
1,300
l.?98
1.284 |,28s
1.270 1.270
l 106 l. 106
1.061 l.06l
i .O53 1.O53
.9665 .9562
.8981 .89?9
.8873 .8879
.8180 .8181
,8105
.8lo\
.7855 ,7855
2. Cnvsrar, Pnopnnrrns or rHE RARE-EARTE ALuMTNUu GanNnrs
Colorr
Lattice
parameter2
(A)
Colorless
Pale Yellow
Calculated
r-ray
density
Index of
refraction3
G/c-')
t2.ltl
5.97r
1 .866
Pink
12.074
12 0+2
t2.otl
11.981
Pale Green
rr.957
6.063
6.193
6.297
6.397
6.476
|.873
1 .868
1 .863
1. 8 5 3
I .854
YbAIG
Colorless
Pale Yellow
lt.929
6.619
1 .848
LuAIG
Colorless
Pale Yellow
l1 .9t2
6.692
1.842
GdAIG
TbA}G
DyAIG
HoAIG
ErAIG
TmAIG
Colorless
PaleYellow
Pale Yellow
Golden Yellow
1 The color exhibited by some samples may be modified due to lead impurities from
the flux in which the crystal was grown.
, CuKar:1.54050 A.
3 S o d i u mD ( I : 5 8 9 0 A ) .
784
MINERALOGICAL NOTES
t2.15
G d T b Dy
Ho Er Tm Yb Lu
r2.to
F
z
12.05
F
.n
z
o
u
lrl
o
| 2.OO
F
F
J
| 1.95
I t.90
64
65
69
68
67
60
A T O M I CN U M B E R
70
7l
Frc. 1. Lattice constant versus atomic number for the rare-earth aluminum Earnets.
T h e G d A I G l a t t i c e p a r a m e t e r1 2 . l l l A u g r " . r w i t h t h e v a l u e 1 2 . 1 1A
determinedby Bertaut and Forrat (1956),but it doesnot agreewith the
value 12.122A extrapolated by Geller et al. (7964a) from their data on
the system Gd3 Fe5-" Al* Orz. In this mixed system the lattice constant
v e r s u s1 i s l i n e a r o v e r t h e r a n g e s0 { 1 ( 1 . 0 a n d 1 . 0 ( 1 ( 3 . 0 a n d t h e e x trapolation was made from the latter range. However, in the system
Y3 Fes-" Al" Orz which was investigated by Geller et ol. (1964b) the
lattice constant versusl behavior is linear up to 1:2.5, but beyond this
point there is an inflection toward the abscissa.A similar inflection might
occur in the Gda Fe5-, Al* Op system for 1) 3.0 which would explain the
discrepancvbetweenthe extrapolatedvalue and our measuredvalue.
Figure 1 contains a plot of the lattice constant versus atomic number
for all the rare-earth aluminum garnets investigated. The resulting curve
is similar in form to one drawn for the rare-earth iron garnets by Espinosa
(1962) and unlike the straight line relation reported by Bertaut and
MINERALOGICAL
785
NOTES
Forrat (1957)for the rare-earthaluminum garnets.An explanationof the
shapeof the curve is given by Espinosa (1962).
The growth habit of YbAIG was examinedby optical goniometry. AII
the growth faceswerefound to be of the dodecahedron[110] and trapezohedron [112] types. The crystal is similar in appearanceto Fig. 135 by
Ford (1958).
The authors wish to thank D. J. Nitti for taking the *-ray powder
patterns and L. G. Van Uitert and W. H. Grokiewicz for growing the
cr1'stals.
RrrrxnNcns
1219-1222.
Brnteur, F. eto F. Fonner(1956)Compt.
Rend.243,
--(1957)Compt.
Rend.24,96 99.
.
Esrrxos,r.,
Phys.37,23M-2347
G.P. (1962)
Jour.Chem.
Fono, W. E. (1958)Dana's TertboohoJ Minera.logy4th Ed. John Wiley and Sons,Inc',
New York, 75.
Gnr.r.rn,S., H J. Wrr,rr.tus,R. C. Snrnwoon aNn G. P. EsprNose(1964a)(to be published).
--H. J. Wrrrr.urs, G. P. EsprNosaeNr R. C. Snnnwooo (1964b)Bell SystemTech'
Jour.43,565-623.
RuuNsruN, C. B. .tNn R. L. B.tnNs (1964)Am. Minerol.49, 1489-1490.
VeN Urrenr, L. G., W. H. Gnooxrowrcz aNn E. F. Dn.qtsonN (1965)Jour. Am. Ceram.
Soc.48.105-108.
THE AMERICAN
MINERAI,OGIST,
VOL. 50, MAY-JUNE,
i965
NEW ANALYSIS OI- GENTH'S VOLBORTHITEI
MancanBr D. FosrBn AND WALDEMART. Scuatlon,
U. S. Geolog'i'cal
Surwy,Washington, D. C.
GBNtn's ANar,vsBs or VoLBoRTHTTE
In 1877 Genth published a paper giving the results of his analysis of
volborthite from Woskressenskoi,Perm, U.S.S.R. Genth recognizedhis
analyses as very imperfect, becausein the material he worked with
volborthite occurred as a crystalline coating on the grains and pebbles,
and in the cavities of an argillaceousconglomerate.He found it impossible
to pick out the volborthite, so crushed the whole mass to separatethe
grains of the conglomerate. The material was then treated with very
dilute nitric acid. He does not specify the strength of acid used nor the
duration or temperature of treatment. The insoluble matter, which
amounted to more than 80 per cent of the sample treated, was filtered off'
and the solution was analyzed. After such a treatment of an argillaceous
1 Publication authorized by the Director, U. S. Geological Survey.