Abernathyite, a New Uranium Mineral of the Metatorbernite Group*

Home , Abernathyite, Autunite, Metatorbernite

ABERNATHYITE, A NEW URANIUM MINERAL OF THE METATORBERNITE GROUP*

NI. E. TuouesoN, Br-eNcno INGnalt, aNo E. B. Gnoss, Lr. S. GeologicalSurttey, Grand' Jwnction, Colo., and' Washington, D' C' and, U. S. Atomic Energy Commission,Grand Junction, Colo' Ansrnecr

Abernathyite, a new uranium mineral from the Fuemrol No' 2 mine, Emery County' yellow, Utah, has the formula K(UO:)(AsOr)'4HzO. The mineral occurs as transparent, fluorescent, thick tabular crystals belonging to the tetragonal system, ditetragonal-di- pyramidal class (4lm 2/m 2/m). The space group is P4/nmm ; ao:7 .17+0'0I A; co:9'08 :1'57010'003, iO.Ot A; o:c--l:1.266;Z:2. Optically, the mineral is uniaxial negative, e o:1,597+0.003. The hardness is between 2 and3. The calculated specificgravity is 3.74. -, The chemical analysis shows,in per cent: KzO,9'5;UO:, 57.7;AszOe,2l'6;P2O5,1'5; HzO Abernathy, operator 4.6;HzOt ,9.9; total, 104.8.Abernathyite is named for the finder, Jess of the Fuemrol mine.

INrnonucrroN AND Acr

OccunnpNcn AND AssocrATEDMTNERALS The Fuemrol No. 2 mine is on a lower slope of Temple Mountain' on the southeast flank of the San Rafael swell, Emery County, Utah' about4T miles southwestof GreenRiver, Utah (Fig' 1)' Mining in the

* Publication authorized by the Director, U. S' Geological Survey' 82 83 ABERNATHYITE, URANIAM MINERAL OF TEE METATORBERNITE

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Frc. 1. Index map of locality of abernathyite' area is in vanadiferous and uraniferous asphaltic sandstones in the Shinarump conglomerate. Temple Mountain, a small elongate mountain, is capped by Wingate 84 M. E. THOTIPSON, BLANCE INGRAM, AND E. B. GROSS

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Frc. 2. Geology of the "collapse" area at Temple Mt., Emery County, Utah. sandstone. Beneath the Wingate sandstone, in descending order, are red standstonesof the Chinle formation, gray Shinarump conglomerate, and red shalesand sandstonesof the Moenkopi formation. A,,collapse', zone (Fig. 2) about 1,800 feet long and 400 feet wide extends below the Wingate sandstonenear the central part of the mountain. The area of disturbedrocks has beencalled the "flop over" or the "tongue.,, Within the disturbed area the sandstonehas bleached white or gray, 85 ABERNATHYITE,T]RANII]M MINERAL OF THE METATORBERNITE

of Iacks bedding features, and is much fractured' fn the upper portions ex- the flop over, large massesof goethitic and hematitic sandstoneare posed. At the Fuemrol No. 2 mine near the lower end of the flop over, the in sandstoneis iight to clark gray and contains nodular massesranging grains diameter from 1 to 5 inches. The nodules are composed of sand

gray clay aggregate. the Abernathyite occurs as a crystaliine coating lining a fracture in sandstone and is associated with yellow-brown earthy scorodite. No other minerals were found associatedwith the new mineral in the samples mine that were avaiiable for this study, but other specimensfrom the contain native arsenic' orpiment, and realgar (T' W' Stern, oral com- two other uranyl munication). Jarosite, pitlicite, metazeunerite, and arsenatesof uncertain composition have also been found'

Pnvsrcer- AND OPTTcALPnopBnups The crystals of abernathyite are unusually clear and transparent for a mineral of the metatorbernite group' They are yellow, have vitreous (3660 Iuster, and fluorescemoderately a yellow-green color in both long pale A) and short (2537 A) wavelength ultraviolet light. The streakis yellow. The crystals are thin to thick tabular in habit and occur singly and in perfect groups. Prominent forms are {001} and {110}' They show a other Lurul .l.urruge, but the cleavageis not micaceousas is typical of minerals of the metatorbernite group. The hardnessis between 2 and,3. As the largest of the crystals is only tests about 0.5 mm. on an edge, it was necessaryto observe the scratch for hardnesswith a binocular microscope. An insufficient amount of the mineral was available for a direct meas- io- urement of the specific gravity, but the crystals sink in methylene dide of specific gravity 3.32. The specific gravity is calculatedas 3.74 for the pure K(UO2)(AsOD'4HrO compound. Abernathyite is uniaxial negative, a:I'597+0'003, yellow, and are e:1.570*0.003, pale yellow to colorless'A few of the crystals anomalously biaxial negative, with 2 V Iessthan 5 degrees' M. E. THOMpsoN, BLANCHE INGRAM, AND E. A. GROSS

Cnnurcar- Axar,ysrs A qualitative spectographicanarysis by K. E. valentine, of the Geo- logical Survey, showed U, As, P, and K present in amounts more than 1

Becausequestions might be raised about the value of a chemical analysis for which such a small amount of material was available, some of the precautions taken in the analysis are stated here. These precautions ,.trial consisted mainly of duplicate analyses and of runs" on artificial mixtures. rt was possibleto make up artificial mixtures containing nearly the correct proportions of As, K, U, and p in advance of the Jemical analysis, becausethe spectrographic analysis, the r-ray powder pattern,

Tesln 1. CHnurcar, Allerysrs or AennwarHymn

Analyst: Blanche Ingram, U. S. Geological Survey

Analysis recalcu- Analysis of lated '4HzO abernathyite to 100 K(UOz)(AsOr) per cent

KzO 9.5r 9.1 9.0 UOs s7.72 55.1 55.0 AszOs 2r.6 20.6 22.2 PsOo 1.5 1.4 HrO+ (e.e) (e.4) HsO- (4.6) (4.4) Total HgO 14.53 13.8 13.8

104.8 100.0 100.0

I A value of 8.8 per cent KzO was obtained in the first analysis. The analysis was then repeated on a larger sample, taking advantage of the information obtained from the first determination. The value of 9.5 per cent KeOls considered more accurate. 2 Average of 57.6, 57.6, 57.9. 3 Average of 14.5, 14.4. ABERNATHYITE, URANIUM MINERAL OF TEE METATORBERNITE 87

Ttnrl 2. Mornculen R.trros ol ColpolleNrs ol Amruernvrrn

Molecular Molecular Analysis weight ratios

KrO 9.5 94 UOa s7.7 286 AszOs 2t.6 230 PzOs 1.5 r42 HeO* 9.9 18 HzO- 4.6 18 and the physical properties of the new mineral made it fairly certain that the mineral was a member of the metatorbernite group and that its formula was probably K(UO) [(As,P)O+]'nH2O. The uranium determination was repeated three times; total HzQ was determined twice. Potassium was determined gravimetrically twice, the first time on a sample of 5 mg. original weight after HzO-, HrO*, As2O5,and IlOa had been determined. A second analysis for potassium was made by F. S. Grimaldi, of the GeologicalSurvey, on a 10-mg.sample which was treated with HCI and HBr to remove the arsenic.The potassium was then precipitated directly. Theserepeat analysesgave consist- ent results. The results of the chemical analysis total 104.8 per cent. No explanation for this high total is offered. The analysis, when recalculated to 100 per cent, agrees very closely with the theoretical composition (Table 1). The molecular ratios obtained from the analysis are very close to ideal proportions (Table 2). The simplest formula to be obtained from these ratios is K(UO) (AsO4). 4H2O. A small amount of phosphorus substitutes for arsenic in the ratio of one part. P2O5to 14.4 parts As2O6by weight'

X-Rav Der,l An *-ray difiraction powder pattern was taken by D. D. Riska, of the GeologicalSurvey, with a Debye-Scherrercamera (114.59-mm.diameter) using Ni-filtered Cu radiation. The pattern of abernathyite very closely resemblesthe patterns of several other members of the metatorbernite group-synthetic hydrogen-autunite, metatorbernite, and metazeunerite. The pattern was easily indexed by comparing it with a pattern of another member of the group whose cell dimensions were known (Table Jt. The cell dimensions of abernathyite and several other minerals and artificial compounds that are generally consideredto belong to the meta- 88 M. E. THOMPSON, BLANCHE INGRAM, AND E. B. GROSS

Tasln 3. X-Rlv Dmrnacuor Powoen Dera. nnn UNn-Crr,r, CoNsreNrs ol AsrnNTaruvrrr Spacegroup: P4/nmm; ao:7 .1710.01A; co:9.08+0.01A; ao:co:l:l'266: Z:2

d(*t \ hkt

10,broad 9.r4 9.08 001 JOJ J. OJ 101 4 J.II 5.07 110 4 4.58 4.54 002 + 4.43 4.43 111 8, broad 3 .84 3.84 102 7 3.59 3.59 200 112 8 3.34 \r.s+ 201 I 3.16 3.02 {t.ot 003 t3.02 2tl 202 6, broad 2.79 iz.sr \2.7e 103 5, broad 2.61 12.63 t l.) 12.62 212 3 2.54 1

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|.69r 224 1r.667 402 t.667 \1.667 330 1.662 JJI 1.662 323 r.646 304 1.641 420 1.625 1.624 412 1.620 205 1.606 fr.ss+ 332 1.582 j 1.s8o 215 ,rr.J/y +21 r.542 403 3 1.5r4 1.512 422 1.508 413 3 t.482 J I .458 6 1.421 3 t.372 1 1.359 1 1.300 5 1.280 A | 261 1, broad r.240 1, broad 1.212 3 r.206 3 1.198 1 |.r87 torbernite group are listed in Table 4 for comparison. We are grateful to Gabrielle Donnay, of the GeologicalSurvey, for the measurementof the

T,lert' 4. Colrp,q.nrsoN ol Umrr-Cor,r DruBxsroNs or AsnnNA.rnvtto wtrrt TrrosB or Orrrun Mnunnns ol rnr MorltonsnnNrrr Gnoup

Mineral or compound on(A) ro(A) Reference

Abernathyite K(UOz) (AsOr) '4HzO 908 Synthetic troegeriteH(uot(Asor) 4H:o 7.16 880 _l Synthetic Na(UOz) (AsOr)' 4HrO 712 8.70 _t Synthetic NHa(UOr) (AsOn)' 4HzO 7.2r 885 -1 Meta-autunite I Ca(UOz)z(PODz. 2i-6iE rO 6.98 8.42 .J Metatorbernite Cu(UOr)z(POr): 8HzO 6.95 2x8.70

I Mrose.M. E.. 1953. 2 f)onnay, Gabrielle(oral communication). M, E, THOMPSON, BLANCHE INGRAM, AND E. B. GROSS lattice constants of abernathyite from Buerger precessionphotographs. The constantsare given as follows: ao:7.!7 +0.01 A; co:9.08f 0.01 A; space group PL/nmm (Drlh); cell contents 2 formula units K(UO| (AsOr)'4HrO. The calculateddensity is 3.74. Beintema (1938) assignedmeta-autunite to the spacegroup P4f nmm, but he had to postulate a statistical distribution of Ca over half the symmetrically equivalent sites in the crystal structure in order to ac- count for this high symmetry. Recently, G. Donnay (oral communication) found that this mineral and others in the group actually have lower symmetries as well as true cells which are multiples of Beintema's cell, so that the cations are in reality in ordered arrangement. On the other hand, her measurementsindicate that the true symmetry of abernathyite is PL/nmm with all the cation sitesoccupied by K ions, of which there are twice as many as there are Ca ions in meta-autunite.

RTTnRENcES

BuNtnua, J. (1938), On the composition and the crystallization of autunite and the meta- autunites: Rec,lravaur chim,, Pays-Bas, 57, 155. Mnosr, M. E. (1953), Synthetic uranospinite: Am. Minerotr.,38, 1159. Muruny, F. M. (1944), Geologic map of the Temple Mountain district, Union Mines De- velopment Corp. (Unpublished map).

Monuscript recei.vedJan. 21, 1955.