THE AMERICANMINERALOGIST,

VOL. 50, MAY_JUNE,1965

MCKELVEYITE, A NEW HYDROUS SODIUM BARIUM
RARE-EARTH URANIUM CARBONATE MINERALFROM THE GREEN RIVER FORMATION, WYOMINGI
Cn,q.nlrsMrr-toN, Br,excnn INcnalr, Joax R. Cr-anxano
Enwlnr J. Dwonwrr U. S. Geol,ogical,
Suraey,Woshington,D. C.
AesrnA.cr
A new mineral of composition

Nui.*,Bu?icu?:s.3inpliuiitco')3-.
sH,ooccurs in 4 subsurface localities some 20 miles apart in Sweetwater County, Wyoming. It is
the fust known mineral with considerable uranium (4.67o as UO) from the Green River
Formation. Two types are known, one (very rare) in apple green crystals and simple
morphology, which has not been analyzed, and a more abundant t1pe, dark green or black,massive and in crystal aggregates, both of which have been analyzed. The massive material
contained 20.7/6 insoluble (organic 8.7/6, acmite 3.50/6,biotite 7.5/s, quartz LD/s); andthe crystal aggregates contained 1816 insoluble (organic 3.0t6, acmite 2.45Ta,biot:iIe9.47o,quartz 3.0/s) . This is the first authigenic biotite recognized in the Green River Formation.
AII these insoluble constituents are presumably syngenetic with mckelveyite. The analysis
of mckelveyite (crystal aggregates) recalculated for these impurities, is BaO 40.6, CaO 4.0,
SrO 1.7, Y2Ox7.7, LazOs 0.09, CezOa0.16, PrzOa0.05, NdzO:0.26, Sm2O30.34, Eu2Os0.19,
Gd2Os 1.18, Tbros 0.38, DyrOr 1.00, HozOs 0.28, Erros 0.95, Tm:O: 0.12, YbzOa 0.61,
Lu2O30.08, UOz4.6, ThOs O.1,Na2O 3.9, K2O 0.1, COz25.7, HsO 6.1, sum 100.2.
The crystals are trigonal, space group P3, a9.L74+O.0O2 L, c 19.15410.007 A, cellvolume 1396.110.7 A3; the three strongest observed o-ray powder lines are 2.942 (100),
4.47 (85), 6.40 A (35). The density calculated for two formula units per cell is 3.62 g cm-3;
the measured density of the massive aggregate is 2.87, of the crystals 3.14; corrected for impurities, the density of mckelveyite in the massive aggregate computes to 3.58, in the crystals 3.47 g cm-3. There is no good cleavage, but fractures are approximately paralled to(0001) and (ll2l). Piezoelectric tests are negative. Forms observed: r {0001}, r {10T1},-ze l0ll2l, m ll0lll,{01T0}. Mckelveyite is uniaxial, negative, e:1.57, a:1.66,
pleochroic, green, @>€,
Mckelveyite with essentially yttria rare earths occurs together with burbankite, acerium rare-earth mineral.
The mineral is named in honor of Vincent E. McKelvey, geologist of the U. S. Geological Survey.
INrnonucrroN

AND OccunnpNcB

In studying waste residuesfrom soda ash production of the trona mineof the Food Machinery Corporation at Westvaco near Green River,Wyoming, tiny green crystals have occasionally been found (Fig. 1).
Although there were not enough of these crystals for chemical analysis,
optical, spectrographic, and r-ray diffraction powder studies indicatethat the crystals represent a leglffiineral species.More crystals of the
new mineral were found in a diire from the Intermountain Chemical
I Publication authorized by the Director, U. S. Geological Survey.

593

C. MILTON, B. INGRAM, J. R. CLARK, AND T,. J. DWORNIK(b)Frc. 1. (a) Green mckelveyite crystal (circled) in matrix of dolomitic marlstone withcoarse shortite crystals. Drillcore, Westvaco, lVyoming. (D) Green mckelveyite crystals
removed from matrix, in trona milling operations at Westvaco

MCKELVEVITE

595

Company John Hay No. 1, Wyoming (Fahey, !962) at a depth of 1557
feet near the main trona bed, associatedwith labuntsovite, Ieucosphenite,searlesite, and other typical minerals of the Green River Formation(Milton and Eugster, 1959; Milton and Fahey, 1960; Milton et al.,1960). Enough material for chemicalanalysis finallybecame available in1959 when the new mineral was found in relative abundance in a few
inches of core taken at a depth of 1576 feet from the Diamond Alkali
Daco No. 3, SweetwaterCounty, Wyoming. The core was obtained by
J. D. Love, U. S. GeologicalSurvey, in the courseof a study of the newly

Frc. 2. Aggregate of mckelveyite crystals as used in chemical analysis. Magnification:
100X. Crystals from Diamond Alkali Daco No. 3 core, depth 1576', SweetrvaterCounty,
Wyoming.

discovered uranium-phosphate dolomite zones in the Wyoming Green
River Formation (Love and Milton, 1959). The several hundred milligrams of crystals (Figs. 2, 3) in this core were usedin the presentstudyi,*
Although these crystals were usually black rather than greenin color, andvaried somewhat in habit from the crystals found earlier, the evidence
indicates that the color differencesare due merely to the presenceof contaminants. The new mineral is shown in typical thin section in Fig. 4.
According to J. D. Love (writt. comm., 1961), the mineral is known tooccur at four localities, all in the Wilkins Peak Member of the Green
River Formation (Fig. 5).
Several years of intermittent labor in handpicking the samples foranalysis were required. The analyses were made on microquantities
and their interpretation presented special problems becauseof the presenceof contaminants.Nevertheless,the resultsof the presentstudy ade-

596

C. MILTON, B. INGRAM, J. R. CLARK, AND E. J. DWORNIK

Frc. 3. Mckelveyite crystals from the core taken at 1576 feet, Diamond Alkali DacoNo.3, Sweetrvater County, Wyoming. Magnification: 150X. Characteristic habit of theanalyzed crystals is shown. The hexagonal base of the crystals is usually dark green or
black; the trigonal array of lighter coiored (to pale green) platelets superposed on the basereveals the three-fold symmetry.

Fre. 4. Thin section in ordinary light showing dark hexagonal mckelveyite crystals in
dolomitic marlstone, associated with semi-opaque limonite (?) and clear dolomite. Specimen from John Hay No. 1, Sweetwater County, Wyoming, depth 1797.5ft. Magnification:

38X.

597

MCKELVEYITE

quately characterizethe new mineral, even though some minor details
may require revision in the future.
The new mineral is named mckelveyite in recognition of the studies of
the Phosphoria Formation of Wyoming and Idaho by Vincent E. McKelvey, geologist of the U. S. GeologicalSurvey. The specimensdescribedhave beenplacedin the collectionsof the U. S. National Museum.
Cnplrrcer, SruorBs oF McKELVEyTTE
Description of samples onil methodsof analysi,s.Two chemical analyses
were made of mckelveyite.The first analysiswas carriedout on 500 mg of

T19N

I n t a r m o u n t ! i n .o h n H l y N o . 1 , l a 7" t797 5'oandWastv!co Tr ) n r M i n a

Gron RiverIa
D i r m o n d A l k . l i D.co No. 31369" 1 76'

TIEN

Parkini Gra.n

liv.r No 3,1785'o

T17N

Dirmond Alk.li Rrid No. 2,1424'
R 1 1 0w

R109W
?

R108W

R107W

g MrLEs

Frc. 5. Map showing the location in Sweetwater County, Wyoming, of the four known occurrences of mckelveyite. Footage indicates depth of occurrence in drill holes.

massive,formlessblack aggregatematerial, and the second,on 180 mg of
selectedcrystals. The sampleswere from the core taken at 1576 feet in
Diamond Alkali Daco No. 3, SweetwaterCounty, Wyoming. Particularcare was taken in assemblingboth samplesto insure freedom from thedolomite matrix. Data from both analyses(Tables 1-6) show the natureof the problems involved and the observeddifferencesbetween the two
samples.
The selection of procedures for analysis was based on initial microspectrochemicalanalysesof the samples by Claude L. Waring, U. S.
Geological Survey. The spectrochemicalanalysesconfirmed the essential
similarity of the massive material and the selected crystals. Only thoseelementsshown presentin amounts greater than0.l/6 were determined

598

c. MILT',ON, B. INGRAM, J. R CLARK, AND E. r. DWORNIK

chemically. Each sample was divided into acid soluble and insoluble
fractions by treatment with 1+3 HCI. Spectrographicanalyseswere
made on both fractions of the black aggregatesample to decide whichelementswere to be determined in each fraction. A similar division ofelementswas assumedto occur in the selectedcrystals. The insoluble
fractions were decomposedfor analysiseither by fusion with NarCO:rorby HF-HClOr treatment. A descriptionof the methods usedfollows,andthe basicdata from the two analysesare given in Table 1.
1) CO2, II2O. Determined gravimetrically. The sample for determination of total COz
and H2O was mixed with VzOs and heated in a combustion train at 900o C. in a stream ofoxygen. The sample of massive material was first treated with 1*3 HCl in a beaker and theinsoluble residue collected in a perforated platinum boat on an ignited asbestos filter. The
insoluble residue in the boat was dried at 110" C. and then ignited in the combustion furnace. Complete transfer was impossible due to the tendency of the residue to creep and toadhere to the beaker. Consequently, the procedure was modified for the sample of crystals,
which was treated with 1*3 HCI in a small Munroecrucible. The soluble portion was separated by filtration and the residue dried and then ignited in the combustion furnace withouttransfer from the crucible. HzO in the soluble fraction is obtained by subtracting HzO- andHzO in the insoluble from total HzO.
2) F. Determined spectrophotometrically with thoron after distillation from HsPOnHCIOr medium. The sample for determination of total F was first decomposed by Na2COr
ZnO fusion; the ftision mixture was leached with HzO, and the leachings distilled. For determination of acid soluble F, the sample was placed directly in the distillation flask and the Fsoluble in HaPOTHCIOT was distilled.
q BaA. Determined gravimetrically as BaSOr.
q CA, SrO, NazO, K:O. Determined by flame photometer.
5) REzOu UaOs,ThOz. The oxides were weighed as a group after separation by NHrOH
precipitations to the phenolphthalein end point. Using a separate sample, uranium was determined fluorimetrically and thorium was determined spectrophotometrically with thoron.
The ignited weight was also corrected for the small amount of Fe:Or present. Total REzOa
was determined by difierence. A concentrate of 3.1 mg. rare-earth oxides, with uranium andthorium oxides, obtained from the analysis of the crystals was analyzed spectrographically,
after treatment with HF to remove Fe2O3(and part of the UaOr), for determination of therelative proportions of the various rare-earths.
6) FezOz (total iron). Determined spectrophotometrically with o-phenanthroline. (Nodetermination of ferrous iron was undertaken.)7) AlzOr Determined spectrophotometrically with alizarin red S.
8) M gO. Determined spectrophotometrically with thiazole yellow.
9) SiOr. Determined gravimetrically after double dehydration.

Includ,ed,organic matter in mchelaeyile.The black coloration that varies
from one mckelveyitecrystal to another, and the excessof total C02 overacid-evolved COz (Table 1) are attributed to the presenceof varying
amounts of organic material included in mckelveyite crystals. The organic matter is presumably amorphous since its presencedoes not affectthe o-ray diffraction powder patterns of mckelveyite samples. Smith(1963) has shown that the oil shaleof the Mahogany zone,Green River599

MCKDLVDYITE
T.terE 1. Cnnurcer, AN,q.LysEsoF Mcrrlvrvrrn
lnou Swrnrweten
Blanche Ingram, analyst (except as noted)

CouNtv, Wvoltrxc

Weight Per Cent

Determined on total sample
Total H:O
Total CO:COz, acid evolution
Total F
L o s sa t 1 1 0 ' C .
Insoluble (1+3 HCD
Determined on fraction soluble in 1+3 HCI
BaO
CaO
SrO
UOrl
ThOr2
REzOt
FerOr
NarO
KrO

sio:
F
H:O (by difference)
Determined on fraction insoluble in l*3
SiOr
FezOr
AlzO:

Massive

Crystals

10.6
4 5. 5
20.0
0.05
0.7
19.7

7.7
30.0
2r.2

JJ

.4

3.0
t.l

3.8
0.11
9.0
0.69
3.6
0 .1 6
0. 3 3
0.02
4.8

33.s
3.3
1.4

3.8
11.0
0 .7 5
3.2
0 .1 0
0.20
5.0

HCI

7.8
3.3
0.69

Mgo
NarO
KtO
C as COzB
HzO

18.2

0.47
0.60
2 2 . r( 2 s . s )
5.1

J.'

0 .1 40.68
0. 3 3o.94
e . 3( 8 . 8 )2.7

I Analyst,
Joseph Budinsky, U. S. Geological Survey.
2 Analyst, Lillie
Jenkins, U. S. Geological Survey.
3 The values in parentheses are those obtained by difierence of total COz and acidevolved COz and are considered more accurate than the values from direct determination
because of the transfer difficulties.

Formation, contains a hydrocarbon of nearly constant composition with
C:80.57o. The reasonableassumption can be made that the organic
contaminant in mckelveyite is similar to that of the hydrocarbon describedby Smith. Thus 8.7 weight per cent of the massivesampleand 3.0

600

C. MILTON, B. INGRAM, J. R. CLARK, AND E. J. DWORNIK

weight per cent of the crystal sample may be attributed to the organic
contaminant (Table 2).
Biot'ile, acmite antl quartz in mckelaeyite.X-ray diffraction powder photographs reveal acmite, biotite and quartz intimately associatedwith
mckelveyite. Acmite and quartz are common authigenic minerals in theGreen River Formation, but biotite has not beenrecognizedpreviously.
T,qslr 2. Couposrrrox Assuuno lon OncnNtc Me.rrnn rN Mcrnr,vovtrB
Weight Per Cent
Analytical data (Table 1):

Total CO:COe, acid evolution
Difference (organic COr)
Equivalent C
Organic matterrl Assuming organic matter with'C:80.5%

Massive

Crystals

4 5. 5
20.0
25.5
70
8.7

30.0
2 1. 28.8
3.0(Smith, 1963).

X-ray diffraction powder patterns were prepared both from selected
mckelveyite crystals and from the residue remaining after mckelveyite
crystals had been treated with dilute HCl. The observeddata for thepattern obtained from the acid-treatedresidueare comparedin Table 3
with representativedata for quartz, acmite and biotite. Selection of
biotite data for comparisonis necessarilyarbitrary, sincesuch data vary,>>_>
I Camera diameter, 114.59 mm.; racliation Ni-filtered Cu, CuKa, f:1.5418 A;
b:broad, d:diffuse. Lower limit of 29 measurable, approximately 7" (13 A;. Fil- no.
16184, powder spindle no. 12397, prepared by Mary E. Mrose, U. S. Geological Survey,
from residue after treatment of mckelveyite crystals with dilute HCl.
2 X-ray diffractometer measurements; radiation, Mn-filtered Fe, Fe Ka, X:1.9373 A;
internal standard, silicon. Annite syrithesized at 600' C., 2,070 bars.
3 Zr-filtered Mo radiation; camera diameter 16 inches. Reference given on A.S.T.M.
card is "Sample from boiler scale."a Ni-filtered Cu radiation; G. C. diffractometer. Reference given on A.S.T.M. card is
Swanson and Fuyat, NBS Circular 539, Vol. III (1953).
5 Line attributed to biotite.

MCKELVEYITE

601

T,tsln 3. x-rev Poworn Drllnacrron Dere coupanro ron Acro-Tnnarro Rrsruuu
ol Mcrnlvl;vrrr lNo Brorrrr, Acurm axn euanrz
Acid-Treated
Residue,
Mckelveyite

Synthetic
AnniteAcmitePresent Studyl

Eugster and Wones(1e62)'

ASTM
3-06213

70
<2
<2
10

a"',"(A)d.u"(A)

IA.2
6.51
5.00

10.264(+ . s t

d

20

I

I

3.64

'
100
5

'''3.:4'91
3.24
3.12
3.01
2.92
2.70
2.60

q

10
5,d
1 5 ,b

2.46
2 -415
2.28
2.23
2.16
2.13
2.005
1.982

5
5

5,b
5
5
z

10

d"o. (A)

6.5

5 .070
4.644

J

5
4.43

1,o
14.26

5

35
3.975
3.7r1

5

3.380
3.t79
3.106

80
15
10

2.734
2.654
2.532
2.465

5
70

3.64

2.99
2.9r

100
40

2.54

60

2.48

27

2.458

t2

2.20

20

2.282
2.237

T2
6

2.12
2.03
1. 9 8
1. 9 3

20
20
7
7

IJ

40

2.t99

20

2.018

10

1.932

J

2
5
5

lr.67s
1

1.692

20

1.68

2.128
1 .9806

1.817
1. 8 0 1

l7
<1

r.672

7

7

1 .659

J

7
7
7
13

1 .608
1. 5 4 1

<l
15

1.820

r.73
J,D

ASTM
5-04904

13
7

ro

Ir.oso1.66
1. 6 3t.6l
1. 5 4
1.51

|.635

1.542
1.514
+plus

additional lines-+

602

C. MILTON, B. INGRAM, J. R. CLARK,AND E. J. DWORNIK

dependingon the compositionof the biotite. X-ray fluorescenceanalysis
by H. J. Rose, Jr., U. S. GeologicalSurvey, of the acid-treatedresidue
from mckelveyiteshowedonlv major Fe. Crushedcrystalsof mckelveyite
were then examinedoptically b1'D. R. Wones,U. S. GeologicalSurvey,
who identified minute biotite fragments among the crushedcrystals andobtained a maximum index of refraction 1.633+0.004. This value,
together rvith the r-ray measurementol 1.542A for dosoindicates thatthe biotite is a variety containing 35 to 45/6 Fe end-member annite

ffi

t;

Frc 6. Electron micrograph of micaceous particles in mckelveyite crystals. 220OOY..

(D. R. Wones,writl. comm., 1961). Comparisonwith the r-ray powder
data for synthetic annite (Table 3) therefore seemsreasonable.AII theobservedlines in the residuepattern can be satisfactorily accountedfor
as due to biotite, acmite, or qvartz. Thus the evidencegiven in Table 3
estabiishesidentification of these impurities intimalell' associatedwith
rnckelvelrite.
In an attempt to examinethe micaceousinclusionsin closerdetail than
was possiblewith optical microscopy, a carefully handpicked grain of
mckelveyitewas preparedfor electronmicroscopestudy. The samplewas
disaggregatedby gentlecrushingand further by ultrasonictreatment in awater suspension.Droplets of the finely dispersedmaterial wereplacedon
collodion-coveredsupport screensand the water allowed to evaporate.

MCKELVEYITE

603

Platy particlesassumedan orientation parallel to the substratewhich on
insertionin the microscopewould be normal to the electronbeam.
Several difierent mounts were scannedin an effort to locate micaceous
flakessuggestiveof biotite. Micaceousminerals transparent to electrons
characteristicallyexhibit a "wavy extinction" such as shown in Fig. 6.
The hexagonaloutlines of the platelets are readily apparent. During thecourseof observation,micaceousflakesand aggregateswere isolatedfrom
the other material in the field of view with the selectedarea diffraction
device. A typical electron diffraction spot pattern obtained and thesampleyielding that pattern are illustrated in Fig. 7. This type of pattern

Frc. 7. Electron diffraction spot pattern of micaceous flakes from mckelveyite
and sa4rple from which pattern was obtained. 3000X.
I

is characteristic of micas and structurally related clay minerals. No
electron diffraction patterns could be obtained for the mckelveyite itself
becauseof the inability oi the electronbeam to penetratethe thicker andmore denseparticles.
With the knowledge provided by the r-ray diffraction and electron
microscope studies, the chemical analysesof the acid-insoluble fractions(Table 1) can be interpreted. The calculationsare presentedin Table 4
and show the approximate weight percentagesthat can be assignedto
each impurity.
Iron in the insoluble fraction was calculated as FerOr which is acceptable for acmite but questionable for the biotite, which undoubtedly
containssomeferrous iron. Sincethe ratio of FeO:FezOain the biotite is
unknown, however, the figures for iron (Table 4) are given simply as total
iron, all FezOe.Biotite analysescited by Foster (1960) and by Deer,
Howie, and Zussman (1962) show the wide range of variability in re-

604

C. MILTON, B. INGRAM, J. R. CLARK, ANl) N. T, DWORNIK

ported biotite compositions. The approximate formula, K2O'6(Fe,M g ) O . ( F e , A l ) 2 O 3 ' 6 S i O 2 . 2 H 2 Om, a y b e a s s i g n e d t o t h e b i o t i t e i nmckelveyite. Consideringthe difficulties associatedwith the analysis ofsuch small samples, the chemical analyses, r-ray diffra"ction data andelectron-microscopepatterns are ali in reasonableagreementand, considered together, confirm the nature and approximate quantities of thesilicate contaminants in mckelveyite.
Tatlo 4. Cnrlrrc,tr Cer,cur,erroxslon Acurrn, Brorrru nxo Quenrz rN Mcr<rr,vrvr:rB

Assumedl

I w"knt lAssu-edl

Molecu- ] Weight lPer Centl Molecu- Weightlar Ratio Per CentlRecal. tol lar Ratio lPer Centx 1 0 4|lroo%lx 1 0 4I

A, Massive aggregatesample, acid-insoluble fraction
SiOr
Fe03 (total l'e)
Al:Or
Mgo
NarO
KzO
HzO
F

553
399
0.69
(0 43)ao47
0.60( 0 .2 3 )003)

l 1. 9 7

920
250
68
to7
76
64
128
l6

304

1. 8 3
t.21

456
174
68
10?

2.74
2.78
0.69
0.43

3 6 .s
37.r
9.2
5:7

64
128
16

060
o.23
0.03

8.0

o.47

o.4
100.0

1197

096

7.50
B Crystals, acid-insoluble {raction

SiOz
Fe03 (total Fe)
AbOr
Mgo
NarO
K:O
HzO
F

800
445
014
0.68
0.33
0.94
(0 28)
0.05

)

t4 87
14 87

1331
2i9
14
170
53
100
155
26

212
53

617
226
14
170

360
0 1,t
0.68

100
155
26

094
028
005

39.5
383
l5

72
10.0
30
0.5
1000

2.45

9.40

3.O2

I Analysis ('Iable 1) of Iraction insoluble in 1+3 HCI of mckelveyite samples; figures {or SiOz and FezOr
also include the value found in the soluble portion of the sample. Value for HzO derived by assuming 3/6 byweight of biotite, Value for F in crystals assumed equal to total F in massive aggregate.
2 Assumed by assigning a.ll NarO to acmite and stoichiometric proportions to Feroa and SiOr.
r Biotite analysis derived from subtraction of acmite from total insoluble plus assumption ol 8 00/6KtO in
massive aggregate analysis, 10 0/a in crystals [The formula given calls lor more Fe (about 1/e FerOr) than
was determined.
a MgO value not determined for massive aggregate sample; value assumed in proportion to the ratio of
KrO determinations in massive aggregate and crystal samples.

605

MCKELVEVITE

Composit'ionof mchelueyite.The results of the spectrographic analysis forrare earths in a 3.1 mg sample of oxides from the crystal sample areshown in Table 5, together with the calculationsin terms of per cent
RE2O3that are usedin arriving at the formula of mckelveyite.
Tesr,n 5. Rena Ea.nrns rN Mcxrlvnyrrr
Weight Per Cent
Rare
earth
element

Calculated

atedt

as RErOr

for

Massive

Recalculatedr
REzOsfor

Crystals

Yttria
La
Ce
Pr
Nd
Sm
Eu

Massive

6.32
043
0.75
023
1.2
1.6
1.0

05
0.9
0.3
1.4
1.9
1..1

0.06
0 11
0.04

or7
0.23
013

007
013
0.04
o.2l
0.28
0.16

Yttrium
earths(otnerthan YrOa)

5.8
l8
5.0

r.4
4.6
0.59
30
040

669
2.O7
574
160
526
067
342
0.45

0.80
025
0.68
0.19
064
008
0.41
006

007
014
0 0.5
o.2l
o29
0.16

098
031
0 8.i
o23
078
0r0
0s0
007

Crystals

6.51

7.69
0.09
016
005
o.26
0.34
0.19

o92

089
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu

I

101
o32
0.86
o24
0.81
0.10
052
0.08

109
1.18
038
1. 0 0
o28
0.95
0.12
0.61
008

380

3 94

4.60

t1 01

tt .3713 38

r Spectrographic analysis made on 3.1 mg of precipitated rare earths, uranium and thorium orides fromcrystals, by Sol Berman, U. S Geological Survey.
z The massive mckelveyite is assumed to have rare earth .atios similar to that of the crystals. Obtainedby multiplying REzOr by l/75.2, then (for massive) by 0 09, (for crystals) by 0.11.
3Obtained by further multiplying by 1/80 and 1/82 (mckelveyite respectively 79.37a it mmsive and
82 2/6 in crystal samples, Tables 2 and 4. From Table 6 slightly difierent, but practically equivalent factors
are obtained, 1/19.6 and 1/82 5).

The calculationsfrom which the proposedformula of mckelveyite is
obtained are presentedin Table 6. The analysesare thoseof the fractions
solublein (1*3) HCI (Table 1) plus the COzevolved on acid treatment(Table 1) plus valuesof H2O obtained by difference,but not including thesoluble Fe2O3and SiO, which have been assignedto the silicates(Table

606

C. MILTON, B. INGRAM, J. R. CLARK,AND E. J. DWORNIK

4). Despite the analytical difficulties, the results from both analyses
agreereasonablywell. If the cation content is calculatedfrom the analysis
of crystals on the assumptionon that there are 32 oxygen atoms in one
formula unit, the following carbonateformula results:

js.3jnni..,ulitco,);-.5H,oNu,'l,Br;.*,cuiCnvsrenocRApHlr .qxo Oprrcs or McrBrvBvrrp
Mckelveyite crystals have trigonal symmetry and the true spacegroupis P3. However, only a few reflectionsviolate the symmetry of spacegroup P3ml , and the morphologyis consistent with presenceof the mirror
plane. The unit-cell constants were obtained from measurementsof'I'.q.erE

6. Ce.lcularroNs

Molecular
Weight,
Oxide

tsaO
CaO
SrO
) alkaline
earthsYrOa
Ce earths
Y earths(other than
Y:Or)
UOr
Tho,
)RErOr
*UOr
Na2O
KrO
> Alkalis
COr
HrO) mckelveyrte
Organic(Table 2)
Acmite(Table 4)
Biotite(Table 4)loR THE Cnnurcal

Analysist
Weight Per CentI

Fonuur-a oF MCKELvEYTTE

Recalculated
Analysis2
Weight Per Cent

Molecular
Ratios

Massive

1 5 335 6 .1
1 0 3. 6

3 3. 4
3.0
t7

33.5
33
14

42.O
38
21

226
341,

5.2
o7

63
09

6.5
0.9

375
270 0
264 0

3.1
38
0 1l

38
.38

39
48
0.1

62.0
94.2

3.6
016

0 .1 0

o2

44.O
18.0

200
4.8

21.2
50

25 1
6.0

257

99.9

100.2

4.5

3 51

2.45

7.50

9 .40

096

302

(Table 4)
Total )
1 SeeTable 1.
z Recalculated to 100/6 mckelveyite.

406
40
1.7

.274
068
020

265
071
.016

.362
o29
.003

. 3 52
.034
.003

46

6,0

.ot2
.o17

0.1

39
0.1

6.r

.060
.o73
oo2
. 0 75
570
.333

.066
.063
.001
.064
.581
.339

1.0

1.2
9.5
5.5

1.0
9.0
<t

607

MCKELVEYIT-E
Taem

7. X-n.tv DrlpnlcrroN
Porunn Dera lon Mcrnr,vnvrtr
T r i g o n a l , P 3 : a : 9 . 1 7 4 + 0 . 0 0 2 , c : 1 9 . 1 5 4 + 0 . 0 0 7A

Calculatedr

hkl
001
oo2
100
10r
003

ro2
103
004
110
111
112
104
200
201
005
113
202
105
203
114
006
204

2r0
211
106
i15
212
205
00?
213
300
301
116
107
302
214
206
303
008
215

dur
1 9 .1 5 4
9 -577
7. 9 4 5
7. 3 3 9
6 385
6 115
4 977
4.788\
4. s87)
1 461
4.137
4.101
3.973
3.890
3.831
3.725
3.669
3 450
3 373
3.312
3.192
3.057
3.003
2.967
2 962
2.940
2.865
2 . 75 8
2.736
2.648
2.623
2.620
2.,587
2.553
2.544
2.488
2.446
2.394
2.363

Measuredz

Calculatedr

drrr

798

5

640

35

5 .03

2d

4.64

<2

4.47
4.15

85
20

3.88

<2
<2

3.32
3.19

2 942

2.648

30
10

hkl
117
304
220
108
221
207
222
310
311
216
305
223
312
009
118
313
224
109
208
306
217
314
400
401
225
402
119
0, 0, 10
315
307

dr,tt
2.350
2.318
2 294
2.292
2 277
2 253
2.230
2.204
2.r89
2.187
2 178
2.158
2.147
2 128
2.122
2.08.3
2.069
056
051
038
023
002
1 986
1.976
1 968
1 945
1. 9 3 1
1. 9 1 5
1.910
1 903

Masuredt

dltt
2 349

2.276
2.229

2 127

2 069

2 040
2 001

1 967

t.767
| .728
1. 6 5 9
1.629
1.578
1.527
1.466

10
10
10
10

)
5

2.445
plus additional lines,
all ilith I<5

I All possible calculated du<r listed for d 2 I 900 A. ttr" tttl are Miller-Bravais indices; i is omitted
2 Camera diameter, 1 t4 59 mm; radiation, Ni-filtered Cu, X(CuKa) :1.5418 A. Lower linit measurablefor
20, approximately ?" (13 A); d:diftuse. Filn no. 16183, powder spindle no.12392, prepared by Mary E.
Mrose, U. S. Gmlogical Survey, from hand-picked green mckelveyite crystals, Sweetwater County, Wyoming

single-crystal precessionphotographs and were refined by a least-squares
analysis (Evans et aL,1963), using the preliminary single-crystal information in conjunction with the measuredr-ray difiraction powder data. The
final values obtained for the hexagonal cell are: a--9.17++0.002,
c : 1 9 . 1 5 4 f 0 . 0 0 7A , c e l l v o l u m e : l 3 g 6 . t + 0 . 7 4 3 . F i n a l i n d e x i n go f t h epowder diffraction lines, and the observed powder difiraction data are
given in Table 7.

608

C. MILTON, B. INGRAM, J. R. CLARK, AND E, J. DWORNIK

Mckelveyite crystals of several different habits were observed (Figs.
|b,2,3). All crystals tend to be platy on c {0001} ; a hexagonaloutline isformed by rhombohedra r {1011} or e l0ll2l. Small hexagonalprism
Iorms m {10101 and -m {0110} may also be present.Other crystals arebounded by the hexagonalprisms m ll0l0l and -m {0110} with small e{ 0112 } terminal forms. The trigonal symmetry is strikingly demonstrated
bv frequent occurrence of a threefold radiating array superposedon ahexagonalbase(Fig.3). No easy perfect cleavagewas noted, but imperfect fractures can be produced approximately parallel to (0001) and(ll2l). Piezoelectrictests were negative. The crystals are opticallyuniaxial negative,e:1.57 and c.r:1.66. Basal sectionsare pale greenand
nonpleochroic;prismatic, strongly pleochroic in green, with c,r)e. The
brown color of the organic matter persistsin the nonpleochroicposition,
so the crystals appear brown rather than colorlesswhen much organic
matter is present.
The measuredspecifi.cgravities of the mckelveyite samplesare 2.87
(massive,by pycnometer) and 3.14 (crystals, flotation in iodomethaneplus acetone). The density calculatedf or two formula units,
lf,

,L

,-

Nai.'sBaa.'oCai.'rSro.zREi.iUi.:(COt;'
5HrO
i n t h e c e l l v o l u m e 1 3 9 6 . 1A t i s 3 . 6 2g c m - 3 .I f t h e m e a s u r e ds p e c i f r cg r a v i ties are correctedfor the presenceof the impurities (Table 4), assuming
specificgravities as follows: acmite 3.5, biotite 2.9, quartz 2.65, organic
matter 1.0, the values become3.58 for the massivematerial and 3.46 forthe crystals. If the same assumptionsfor the silicatesand organic areused, pius the calculatedvalue of 3.62 for mckelveyite,a value of 2.89 isfound for the massivesample (comparedwith 2.87 measured)and 3.25
f or the crystals(comparedwith 3 . 14 measured).
R,q,nB-B;rnrnCoNroNr Colrpennt rN McKEr,vEyrrE AND BunnaNrrro,
aNl ExrlrpuFrcATroN on Onno AND HARKTNS'Ruto rN MCKELVIyrlE
Mckelveyite and burbankite (Pecoraand Kerr, 1953) are both probabiy fairly widespreadmineralsin the Wyoming GreenRiver Formation;
burbankite is also known from many Green River localities in Utah
(Milton and Eugster, 1959). Compositionsof these two rare-earth carbonates are compared in Table 8, which includes analysesfor burbankite
from Montana (Pecoraand Kerr, 1953),Wyoming, and Russia (Borodin
and Kapustin, 1962). These analysesshow that the rare-earth content ofburbankite remains relatively constant despite the mineral's occurrence
in diversegeologicalenvironments(e.g.,alkalic pegmatite and lacustrine
Green River). Even though mckelveyite and burbankite (Fig. 8) are
presumably formed under virtually identical geochemicalconditions,inthe sameplace at the sametime, the two mineralsare altogetherdistinct

MCKELVL,YITE
Tanr,B 8. Coulosrrroxs
BuneeNrrrn

Coupenrl ron McrelvrvrrE
FRoM Wvoutlc
rnolr Wyournc, MoNreNn. lno Russra.

Mckelveyite

BaO
CaO
SrO

Wyomin92

406
4.0

Major

MontanaB

14.02
1 3. 6 8
19.70

r.4
.to

46.3
Y:Oa
La:oa
CezOr
Pr:O:
NdzOa
Smzo:
EuzOa

,J

0.09
0 .1 6
0.05
0.26
034
0 .1 91.2
t2'rmzo:
YbzO:
LuzOr

UOz
ThOz
NarO
KrO
) alkalies
COz
HzO
AlzOr
Fe:oa
Mgo
SiOz

Russias

1 1. 6 2
10.86
t2 86

14 60
9. 8 1
9.96

2.34
4.65
0.37
r.40
0 .1 0

1.2

Russiaa

47.40
0 .1 00.05

3 5. 3 4
0.00

34.37
0.26

4.73
8 .1 8
053
t.6t
0.06

4.24
8.34
0.64
2.45
0.t7

042
1.1

GdrOr
Tb:oa
DyzOr
Ho:oa
ErzOr

awo

Burbankite

Wyomingr

11

609

5.4

118
0. 3 8
1.00
0.28
0.95
o.l2
0.61
0.08

8.86
0.08

15.84
o.t2

r0.17
33.39

12.93
32.14
2.60
0.00
0 .1 0
000
0.06

12.43
34 30
097
1.05
0.48
0. 3 50 .1 998.42

100.23

46
4.6
0.1
3.9
0.1

4.0
0.1
40
25.7
6.1
0.0

10.17

4.1

100.2

I Mckelveyite, Wyoming, this report
2 Burbankite, Wyoming-preliminary
spectrographic data-unpublished.
3 Burbankite, Montana-Pecora and Kerr, 1953.
a Burbankite, Karelia, Russia, Borodin and Kapustin, 1962; greenish-yellow
in dolomite-ankerite.
6 Burbankite, Karelia, Russia, Borodin and Kapustin,or pink

1962; yellow in calcite.

610

C. MILTON, B INGRAM, J. R. CLARK,AND II,. J. DWORNIK

from one another in rare-earthcontent. A virtually completesegregationof yttrium earths has occurred in mckelveyite, whereas cerium earths
have segregatedin burbankite. The controlling factor in such rare-earth
segregationcannot thereforebe the geochemicalenvironment but must
instead be attributed to the crystal chemical character of the minerals.
In monazite and xenotime, often associated,a similar segregationis
observed.
Fig. 9 shows that the cerium earths in mckelveyite conform to Oddo
and Harkins' rule, the quantity of the various elementswith even atomic

Frc. 8. Black mckelveyite crystal aggregate with burbankite seam (arrow) separating itfrom light gray dolomitic limestone at top. Magnification, 100X.

numbers always exceedingthat of their neighborswith odd atomic number (Rankama and Sahama,1950).
RanroRcrrvrrY oF McxBrvpvrrB
Attention was first drawn to the core containing mckelveyite becauseof
its strong radioactivity. J. D. Love, U. S. GeologicalSurvey, in a written
communication(January 29,1963),noted that the coreswhich later were
found to contain mckelveyite were among the most radioactive of alltested by 7-ray scintillator in his examination of several thousand Green
River cores and outcrop samples. Nevertheless, after separation of themckelveyite, the radioactivity (and also the phosphate content) of theremaining material were found to be quite low, a result which showsthat
thesecoresdid not owe their radioactivity to the presenceof uraniferous
apatite. It may also be noted that the zone in which mckelveyite occurs

6tl

MCKELVEYITE

in the basalWilkins Peak appearsto contain more Ce, La,Y, Sc, Ga, Yb,
Nd, Ti, Zr, Cu and Nb than any uraniferous phosphatic zone in the Wilkins Peak Member of the Green River Formation. This zone is also the
only one in Wyoming known to contain Sm and Sn (Love, in press.)
with a half-Iife oI 6.7X1011years is radioactive, being the only
Sm1a7
known natural emitter of alpha particlesasidefrom the heavy radioactive
elements(Hand. Chem. and Phys. 196I-2, p. a83). However, the strong
radioactivity of the core is largely attributed to the uranium content of
125:ils,:i";".,:; :;i;:3 ?T ::

:: ::

::

H #

:;

'"T ;3 ii

I-rc. 9. Oddo and Harkins' Rule, exemplified in mckelveyite'mckelveyite, the first mineral with considerableuranium content to befound in the Green River Formation.
Irving A. Breger,U. S. GeologicalSurvey,has suggestedthat during or
following deposition of the Green River sediments, the rare earths insolution were entrapped or chelated by organic complexes,and this local
enrichment of nucleation eventually resulted in formation of rare-earth
mineral complexes,such as mckelveyite. Meanwhile the originally lightcolored organic matter underwent bombardment by the radioactive elements present, thus causing the black coloration of the organic material
associatedwith mckelvevite.
Acrwowr.nncMENTS
We are deeply indebted to many of our colleaguesat the U. S. Geological Survey for assistancein this study. Experimental results were6t2

C. MILTON. B, INGRAM. J. E. CLARK. AND E. I. DWORNIK

made available by the following: S. Berman, H. Worthing, and C. L.
Waring, spectrographicanalyses;I. Ma1', J. Budinsky, and L. Jenkins,chemical analyses; M. E. Mrose, r-ray diffraction powder patterns;
H. J. Rose, Jr., x-ray fluorescenceanalysis;D. E. Appleman, refinementof o-ray diffraction powder data; J. A. Denson, photographsof crystals
and thin section. The mckelveyite specimens used in the chemical
analyseswere provided by J. D. Love. Critical comments on the entire
manuscript by M. Fleischer,Mary E. Mrose, D. R. Wones, and W. H.
Bradley were most helpful. I. A. Breger participated in numerous discussions of the problems associatedwith the organic contaminant,
D. R. Wones gave valuable assistancetowards elucidation of the problems related to the biotite, and J. W. Adams gave helpfui discussion
relating to the rare earths.
RrlBtBNces
Bonoorr,r, L. S. aNr U. L. KapusrrN (1962) [Burbankite-first
discovery in U.S.S.R.]
Doklady, Akad. Nauk. SSSR 147, 462-+65. Abstract in Chem. Abs. (1963) 58, 8779.
Dren, W. A., R. A. Holvrn and J. Zussuax (1962) Roch-Forming Minerol,s,I,rol,.3: Sheet
Sili,cates.Longmans, Green and Co., London, 58 60.
Eucsrnn, H. P. em D. R. WoNos (1962) Stability relations of the ferruginous biotite,annite. Jour. Petrology3,82 725.
Evaxs, Howann T, Jn , D,lxmr, E ApplrueN aNo Davro S. HaNorvBnren (1963) The
least squares refinement of crystal unit cells rvith powder difiraction data by an automatic computer indexing method [abs, E-10]. Program and Abstracts, Am. Crystal
Assoc. meet., Cambridge, Mass., 42.
Fanrv, J. 1.0962) Saline minerals of the Green River formation. U. S Geol Surtey ProJ.
Paper 4O5,
Fosrrn, Mencannr D. (1960) Interpretation of the composition of trioctahedral micas.
U . S. Geol.Su.rtey Prof Paper 354-8.
Handbooh oJ Chemi.stryand Physi.cs.43ded. (1961 2) Chem. Rubber Publ Co., Cleveland,
Ohio.
Love, J. D. (in press) Uraniferous phosphatic lake beds of Eocene age, Wyoming and Utah.
U. S. Geol. Swoey ProJ. Poper 474-E.
--AND Cn,lnr.rs MnroN (1959) Uranium and phosphate in the Green River formation of Wyomin g labs I Geol. S oc. A m. B illI 7O, 16+0
X{rr.roN, C , E. C. T. Cseo, J. J FlHnv aNo M. E. Mnosr (1960) Silicate mineralogy of theGreen River Formation of Wyoming, Utah, and Colorado. Report Intl,. Geol,.Congress,
XXI Sess.,Par, XXI, 171 184.
Copenltogen,
H. P. Eucsrrn (1959) Mineral assemblagesof the Green River Formation. RasearchesinGeoclrctnistry.P.H
Abelson,ed.,JohnWileyandSons,NervYotk, 118-150.
-eNn J. J. Fanrv (1960) Classification and association of the carbonate mineral of theGreen River Formation. Am. Jour. Scl. (Bradley Vol.) 258-A, 242-246.
Prcote, W. T, eNo Jor H Krnn (1953) Burbankite and calkinsite, trvo nerv carbonate
minerals from Montana Am. Mineral,.38, 1169-1183.
RaNraur, K. e^*o Th G. Sau,lltr, (7950) Geochemistry.Univ. Chicago Press.
Srtrn, Joau lVann (1963) Stratigraphic change in organic composition demonstrated by oil
specific gravity-depth
correlation in Tertiary Green River oil shales, Colorado. Am.
A ssoc. P etroleum. Geol. Bull. 47, 804-813.
Manttscript recei'oed,September3, 1961; aecepted.
for publi.cotion, September20, 196't.