Mineralogy of the Zippeite Group 433

C anadian M ine raloei.st Vol. 14, W, 429436 (1976)

MINERALOGYOF THEZIPPEITE GROUP

CLIFFORD FRONDEL Department of Geological Sciences,Hamatd University, Cambidge, Massachusetts

JUN ITO James Franck Instilute, University ol Chicago, Chlcago, Illinois

RUSSELL M. HONEA 1105Bellatre Street,Broomtield, Colorado

ALICE M. WEEKS Department of Geology, Temple University, Philadelphia, Pennsylvania

ABsrRAcr en trois groupes, chimiquement et aux rayons-X, selon qu'ils contiennent: K ou NHa, Na, ou un The ill-defined mineral zippeite and a number cation divalent. De nombreuses solutions solides of zippeite-like minerals, hitherto supposed to be existent entre pOles i cations divalents, mais non hydrated uranyl sulfates, are found to contain one K et Na. Le compo# correspondant au p6le Na or another of various monovalent or divalent ca- est orthohombique avec a 8.80, b 68.48, c 14.55L; tions in addition to uranium. They correspond to tous ces min6raux possddent une m0_me pseudo- syntletic phases with the formula l"(UOr6(SOrg maille avec 4 -8.8. b -17.1, c -7.2L. (OH)ro.yHgO, where A is K, Na or NHa (with La nature chimique de la zippEite type de Joa- .r-4 and y-4) or Co,Ni,Fe2+,Mna+,Mgln (with chimsthal (J. F. John 1821) n'est pas connue. Un r=2 and y-16). All are structurally related but min6ral analogue, d6crit par R. Nov6dek (1935) et three subgroups are indicated by X-ray and ch€m- provenant de la m0me localit6, est identifi6 corrme ical evidencel the K and NHa members, the Na potassigueet est consid6r6 comme n6otype. D'autres member, and the divalent cation members. Extensive phases naturelles ont 6t6 identifides; ce sont les solid solutions exist between the divalent cation zipp6ites de sodium (la plus commune), de cobalt, members but not with the K and Na members. The de nickel, de maen6sium et de zinc. Un min6ral Na member is orthorhombic with 8.80. a , 68.48. alt6r6 repr6sente probablement la zipp6ite de fer. c 14.55A; all of the members relaied to are an Les efforts faits pour synth6tiser les zipp6ites de orthorhombic pseudocell -8.8, -17.L, with a 6 Ca et de Cu ont 6t6 vains. c -7-24. Clraduit par la R6ddction) The chemical identity of tle type zippeite of J. F. John (1821) from Joachimsthal is not known. A INTRoDUCTIoN similar mineral described by R. Nov6Cek (1935) The fint uranium sulfates found in nature from the same locality is identified as tle K member and is taken as the neotype. Other identified were recognized by the German chemist J. F. natural phases include sodium-zippeite (the com- John in 1821.. At that time the only otler known mon member), cobalt-zippeite, nickel-zippeite, mag- uranium minerals were the species subsequently nesium-zippeite and zinc-zippeite, An altered min- called uraninite, torbernite and autunite. John eral probably representing the iron member also described and qualitatively analyzed an emerald occurs. Efforts to synthesize the Ca and Cu mem: green uranvitriol and a yellow earlhy basisches group bers of the failed. schwefelsiiures uranoxyd from Joachimsthal, SorvrvrernB Czechoslovakia. The uranvitriol later was described crystallographically and named johan- La zipp6ite, min6ral mal d6fini, ainsi qu'un cer- nite by Haidinger (1830). The yellow earthy tain nombre de min6raux analogues, 6taient consi- sulfate was named zippeite* by Haidinger (1845) d6r6s jusqu'ici comme des sulfates d'uranyle hydra- but without further description. t6s; ils s'avdrent contenir, outre l'uranium, I'un ou I'autre de diff6rents cations monovalents ou diva- Minerals attributed to zippeite have since Ients. Ces min6raux correspondent aux phases syn- th6tiques l"(JOr)0(SOJa(OH)ro.)HzO, of I est Il Na ou NHa (avec r=4 et y=4) ou bien Co, Ni, *A memorial of Frantiiek X. M. TipW GlSt- Fe2+, Mnz+, Mg Zn (avec x=2 et y=16). IIs sont 1863), Czech mineralogist, is given by Kettner tous apparentes par leur strucfure, mais se classent (l963). 429

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been found at numerous losalities but their This included members found here to be iden- study has been attended by nany difficulties. tical with various natural zippeite-like rninelals. In part this has been caused by the very fine- The latter have been named zippeite (the K grained and admixed uature of the material and member of the group), sodium-zippeite' cobalt- by the quite limited samples available for zippeite, nickel-zippeite, mapesium-zippeite and analysis. The main source of trouble, holvever, zinc-zippeite. These names have the approval bas been the long-standing belief that the min- of the Commission on New Minerals and Min- eral was a hydrated uranyl sulfate. It is now eral Names of the I.M.,\ fouud that the earlier analyses were incomplete, and that the minerals and synthetic compounds METHoDS oF SYNTHESIS hitherto loosely grouped around the name zippeite contain one or another of various mono- Zippeite-type phases were precipitated fron valent or divalent cations in addition to the acid solutions containing uranyl sulfate to- uranyl ion. gether with sulfates of K, NII+ Na, Co, Ni, The earlier ilrrrmary accounts of natural and Fe'+, Mn2+, Mg or Zn. Precipitation was ef- synthetic so-called zippeite by Nov6Cek (1935), fected at room temperature by the addition of Traill (1952) and Frondel (1958) constitute a NILOH (or NaOI{) to solutions containing composite description of a group of related sub- divalent cations and of KOH, NaOH or NIIIOH stances.They believed tle mineral to be a hy- to solutions containing the corresponding mono- drated uranyl sulfate. This situation gave rise valent sulfates. Experimentation established to complications during the 1950's, a period of that the phases are pri:cipitated in acid solutions active study of tle mineralogy of uranium, when over a wide range of molar ratios and con- supposed uranyl sulfates falling within the range centrations. Control of pH is essential. In gen- of properties attributed to "zippeite" were found eral, if a dilute alkaline solution is slowly added at many places. Some of these substances were dropwise with vigorous stirring, bringing the tentatively referred to by new names, such as pH up to 4.O4.2, a precipitate will form on the meta-zippeite, meta-zippeite-I, meta-zip- standing for hours or days. Under these condi- peite-Il aud beta-zippeite mentioned by Gruner tions only a small proportion of the dissolved et al. (1954) and othen. A few occurrencesbe- cations is precipitated. If the precipitation is ef- came known informally by the name of the fected at somewhat higher pH, becquerelite or mine in which they were found, such as "Happy other phases in either crystalline or amorphous Jack zippeite" and 'Ilcky Strike zippeite". form may coprecipitate. With regard to the identity of the original The rapid addition of the alkaline precipitant, mineral from Joachimsth4l,Nov6dek (1935) did depending on its normality and the vigor of not succeed in finding type specimens of John's stirring, may locally give a relatively high pH material and based his description and micro- with accompanying immediate precipitation of chemioal analyses of zippeite on certain non- becquerelite. This may then redissolve slowly. type specimens from the same locality. He The rather divergent ratios of UOa to SOg re- thought that the rather variable material repre- ported in some analyses of synthetic material sented a series of hydrated uranyl sulfates. may be due to admixture of becquerelite. Uranyl Frondel (1958) obtained three of tlese speci- sulfate solutions that are nearly saturated with mens*, found them to be similar to a syn- the monovalent or divalent sulfates, and that thetic compound reported to be a hydrated have an initial pH below 3, generally yield satis- uranyl sulfate, and described this material as factory results. zippeite-proper with the composition 2UOg' The use of NaOH in precipitating the divalent SOa'5HzO. cation and K members often results in the co- Following the recognition early in the present precipitation of the Na mernber. This precipitates study that certain synthetic zippeite-like pre- fust and may then be followed, on standing, by parations contained K as an essential sonstituent, the divalent cation compound. The Na msmber two of Nov6dek's specimens and the earlier is commonly admixed in natural material. analyzed synthetic compound were re-analyzed The particle size of the precipitates tends to and found to be a potassium uranyl sulfate. An increase with time when left in the mother extensive program of phase synthesis was then solution, but crystals large enough for single- undertaken that led to the recognition of a crystal study could not be obtained even after large group of structurally related compounds. several months. In general the particle size in- creases with decreasing pH at the level' of precipitation and with increasing dilution. Zip- *Kindly supplied by Dr. Karel TuCek of the Na- peite-type phases genfsining Ca or Cu could tional Museum in Prague. not be synthesized.

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Gnoup DEscRIprroN X-ray methods failed because of the very poorly crystallized nature of the precipitates. Extensive The composition and properties of the mem. mutual substitution between the various divalent bers of the zippeite group are summarized in cations is indicated in natural material. this section. Details of the individual members are given in following sections. X-ray crystallography Chemicql composition X-ray study indicates that all of the members have identical or very closely related The 8 chemical analyses of natural and syn- structures. Single-crystal study by the Weissen- thetic materials referred to zippeite are srunma- berg and precession methods of an analyzed rized by Frondel (1958): they are all believed to natural Na member did not afford a satisfactory have overlooked K or other cations. The L3 new determination of the unit cell and space group. chemical analyses reported here for natural and The unit cell is orthorhombic and very large, synthetic material indicate that the general with a 8.8O, D 68.43, c 14,55]t There is a formula for the group is ./"(UOr)s(SOe)'(OII)ro. marked pseudocell, C face-centered, with a yHrO, where r{, includes the monovalent sations 2.21, b 2.84, c 7.275l.. Most of the reflections K, Na and NIL (with .r=4, y=4) and tle on both single-crystal and powder photographs divalent cations Co, Ni, Fe, Mn, Zn, and Mg can be indexed in terms of larger pseudocells (with r=2, y-16), The mouovalent and divalent with a 8.80, D 34.24 or 17.12, and c 7.275 or cations probably occupy all or half of a single t4.554, but the true cell, verified by vely structural site. strongly exposed photographs, has 6 68.484. Syntheses effected from solutions containing The space group is not known. The only sys- varying ratios of K and Na establish that there tematic extinctions established with certainty is a small mutual substitution of K and Na are (0OD with I odd. Single-crystal X-ray study near the end-compositions but that K-rich and rvould be very desirable for other members of Na-rich phases otherwise coprecipitate. The K the zippeite group but suitatle crystals are member slowly recrystallizesto tle Na member lacking. A partial indexing for the Na member when immersed in a concentrated solution of of the group in terms of a pseudocell with a NaCl, but the Na member does not convert in 5.82. b 17.1.2and c 7.324 is given in Table 1. a KCI solution. There is a complete solid-solu- The X-ray powder data for syntletic and na- tion series between the Co and Ni members in tural members of the zippeite group aie given synthetic material and probably also in natural in Table 1. The powder photographs of the material. Efforts to investigate the solid solu- members of the group are all similu but three bility between the Co, Fe and Mg members by subgroups comprising the K and NIII members,

'I. TABLE X-MY POIDERDATA FOR I}IE ZIPPEITEGROUP

Zlppelto, Zlppeite, Sodi@z i ppelte Cobalt-zlppelte Nlckel-zlppelte, ilagnesl@-Ztppelte Z.inc: ll,rlganeser l 3ynthetlc* 'loachio- syn thetl aJ. Nlcksl-zlppelte Happy Jack trlne lqcky strlke Elne* zlppelte, zlppel te, stlEls synthetic sylltlEtlc sYntietl Cl r 4** r 4*ut J d*ua d"u1" &x r 4r"t t 4""r r 4*"" r 4eas / 4."" 'I 7 8.58 2 8.60 8.56 8.56 020 9.82 37 9.63 1 9.7 33 9.62 12 4,52 100 6.95 l0 7.06 t00 1,34 7.32 001 s.70 9 9.04 I 7,2 l0 8.52 r00 7.15 2 5.24 | 6,24 4.715 4.705 121 100 7.21 19 8.51 1 4.9 100 7.08 5 6,22 'fI12 5.41 3 5.45 4.270 4.280 040 5.54. 7 7,69 1 4.2 9 5.45 12 5,49 4.29 2 4.29 4.004 4.009 131 4.88 93 7.10 8 5.19 5 4.29 10 4.24 I 3.89 l4 3.754 3.777 201 4,23 12 6.41 l0 3.58 14 4.84 l0 4.19 4 3.85 3 3.66 3.663 3.660 002 B 3.94 I 3.48 2 4.53 5 3.93 21 3.62 9 3:50 44 3.490 3.480 230 I 3.69 12 5.47 6 3.ll 7 4.24 6 3.67 77 3.4A2 I 3.12 3.153 3.150 231 46 7 5.19 2 2,8 9 4.lS 50 3.583 8 3,227 4 2.87 2.858 2.853 060 22 3.47 19 4.82 3 2,74 l0 3.89 41 3.453 66 3.108 2 2.72 5 2.666 2.675 222 2a 3.12 26 4.19 2 2,52 50 3.54 6 3.317 22 2.860 4 2,65 9 2.529 2.526 232 16 3.90 1 2.49 35 3.44 54 3.1t0 s 2.698 3 2.47 2.439 2,M0 003 I 2.865 4 3.27 12 2,863 20 2.&4 2 2,4 2.253 2,250 062 4 2.739 100 3.45 26 3.100 19 2.660 3 2.592 4 2,22 'll8 2.206 2,205 400 'llt0 67 3.10 8 2.860 16 2.48:t 21 2.460 2 2,14 2.il8 2,119 213 2.491 21 2.45 8 2.650 6 2.391 t0 2.321 2 2.n 2,023 2.030 072,92 8 2.388 15 2.724 15 2.467 2 2.3t2 7 2,239 3 2.05 2.N2 2.004 ?62 2.303 30 2,644 3 2.362 I 2,227 13 2.210 3 1.94 1.891 1.889 402 2,&3 '1031 2.481 4 2.276. 5 2.165 13 2.189 1 1.87 tl ].746 1.745 460 2.180 2.380 6 2,227 4 2.t35 7 2.140 2 1.75 ].701 1,704 282 I 2.140 7 2.292 6 2.160 l0 2.075 't28 2.089 2 1.70 2.@0 21 2.227 6 2.467 5 2.U7 2.U1 I 1.69 't2 z,0g 12 2.1U 4 2.@8 6 2.Clr 22 1.932 1.963 19 2.128 15 r.943 t8 r.957 r0 2.075 3 1.892 4 1.85s 6 1.797 7 2.M5 3 1.924 8 1.834 I 1.752 l5 I.955 2 1.77? 4 1,795 't2t5 1.741 't27 r.853 7 1.695 6 1.747 1.697 1.V5 6 1.728 12 1.687 l0 1.69 8 1.580

*olffractoEter recordlng, cu radlctlon, Nl flltcr. Peak helghts tn arbttrqry chart untts. *Fllo recordlng, 114.6 m dl@ter c@ra. Cu radl8tlon, Nf fflt€r. +lndexlng for cell f,lth a 8.a2, b 17.12. a 7.3^.

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the Na member, and the divalent cation mem- fourlings, has symmetrical extinction Y to Y' bers can be distinguished. These subgroups of about 74o. There is a perfect cleavageparal- correspond to limits in the mutual substitution lel to the flattening, or (010), with a suggestion of the cations iniolved and to differences in tle of a cleavage inclined to this plane. degree of hydration. Efforts to index the pat- The indices of refraction fall into two groups: terns of all members of the group in terms of the divalent cation members, with a in tle the stated pseudocells for sodium-zippeite failed range 1.70 to L.75, and the Na and K members, although some of the stronger lines can be in- with cx 1.63 and 1.65 respectively. The optical dexed in collmon. The three subgroups prob- study of the natural minerals is rendered diffi- ably have different although closely related cult by the generally fine-grained nature of the structures. Traill (1952) has described a mono- material and especially by the frequent ad- clinic synthetic phase that is very similar in mixture of compositional variants, as in ef- its X-ray powder pattern and refractive iudices florescent crusts with a complex history of to the K member, zippeite, but that diffen in dqnsition. Sodium-zippeite and, less frequently, symmetry and cell geometry from sodium- the potassium member, zippeite, occur intimate- zippeite. ly admixed with other members of the group. The natural materials are frequently very fine-grained mixtures that cannot be separated 0ccurrence so that extra lines in the powder patterns are The members of the group are all secondary a cornmon problem. in origin and typically occur in the oxidized zone of uraninite deposits sqataining sulfides. Physical and optical properties They are also found, sometimes abundantly, as In synthetic material, the K and NHa mem- efflorescenceson the walls of mine workings. bers are golden yellow in color, the Na, Mg and Gypsum, uranopilite and johannits 11s gemmoD Zn members are yellow, the Co and Ni mem- associates.The sulfate content of these minerals bers orange to tan, the Mn member dull orange comes from the oxidation of the sulfides, chief' brown, and the Fe member yellowish brown. ly pyrite and chalcopyrite, but including smal- All fluoresce bright yellow in both short- and tite-chloanthite and other CoNi minerals in the long-wave ultr'aviolet radiation, somewhat less case of the Co and Ni members of the group. strongly in the Co, Ni, Mn and Fe members. Sodium-zippeite, the more common member The hardness could not be determined precise- of the group, is typical of deposits of the so' ly but is near 2. The specific gravity is more called sandstone t54te. Zippeite is more typical than 3.3 for all members. of weathered uraninite vein occurrences in Crystals of both the natural and synthetic igneous or metamorphic rocks. members are microscopic in size. They com- ZTpPF,TTE. prise rhomboidal to slightly elongate plates with very similar angles in the different members as The redefinition of zippeite as the K member measuredin plane section under the microscope. of the group is based on the re-examination of Rounded rhomboidal crystals together with material studied by Nov6dek (1935) and on the petal-like, spindle-shaped and lath-like shapes identity of this material with synthetic potas- are common. The obtuse internal angle of the sium uranyl sulfate. An identisal mineral also rhomboids is near 106o. Vermicular aggregates was found on old specimenslabelled uranochre or stacks of crystals joined by their flat sides from Joachimsthal (acquired in 1821 for the are common. Warty crusts and dense to earthy Harvard collection) that probably are contem- aggregates composed of minute shreds also occur. TABTE2. CHEI.IICALANALY5ES OF ZIPPEITE Optically, the crystals conform to ortho- I rhombic symmetry. The optical orientation is f2o 8.17 7CO an4 the same in all members: the acute bisectrix X NaZ0 is perpendicular to the plane of flattening and uol 74.39 75.38 '10.41 'I',l cleavage, (010), with Z parallel to the elonga- so3 .41 tion or c-axis; 2V(-) is moderate to large. All Hzo 7.03 4.92 members are pleochroic with X colorless to pale Iotal I 00.00 99.60 yellow, Y yellow, Z yellow golden yel- '1. dark to Calculated for (0H) K4(UOr)6(s04) 3 I 0.4H20 low. Twinning is common. The most common 2. Synthetlc rnter'lal. Jun lto, analyst. Sanple dried at twin law is on a (l0I) plane with symmetrical r05.c. extinction Z to Zt of about 28o. Another type 3. Joachi$thal. Jun lto, analyst. Heavymtals pr€sent only la spectrcgraphlc traces- Loss at 500'C 10.79. of twin, sometimespolysynthetic or repeated as optical and X-ray data ldentlcal wlth syrthetlc naterial.

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TABLE3. OPTICALPROPERTIES OF ZIPPEITE Sotruna-ZlrrrrrB '1. This mineral, the most common member of Synthetic Synthetic'1954) SJmthetlc (present study) (Gruner (Trai1l l952) the group, was recognized as a distinct mineral a 1.654 1.657 1.655 as early as 1950 by the writers and others on B 1.716 1.720 1.717 Y 1.768 the basis of its optical properties (Table 4) and 7. X-ray powder pattern (fable 1). An adequate .loachlmthaI Colorado Schneeberg Nlllslde (Larsenl92l ) nlne, Utah '1.657 1.660 1.657 TABI! 5. CHEIT,IICALNALYSES OF SODIW.ZIPPEITE 6 1.710 1.717 1.720 a 1.760 1.767 -1 .77 1. 2. 5. 6. Na20 4.96 4.9r 5.25 5.09 0ptlcally negatlv€ wlth 2Il large. PleochDlc wlth : colorless, Y pale yellfi, z yel lor. K2o 0.19 0.47 0.42 uc^ 76.53 73.76 76.79 76.92 75.86 74.'l 503 10.71 9.63 10.39 10.22 t0.43 12.5 Hzo 7,23 10.25 7.43 7.62 7.99 7.89 TABLE4. OPTICALPROPERTIES OF SODIIJI'I-ZIPPEITI Total 100.00 99.49 99.57 99.86 l. 2. tro*o: tloo.oo: '1. Synthetlc llelta Blne, Atonlc Klng Capltol Calcu lated frcn Nar(u02)5(s04)3(0H)tO.4HZ0 Utah nin€, Utah Reef, utah Jun lto, analyst' Analysls 4 on '1.637 2,3,4. Synthetlc nater'lals. o 1.630 I .630 homgen@us naterlal frcn solutlon contalnlng Na: K'4 : I' 0 1.690 1.688 1.688 'r 1.689 1.738 I .738 1.731 I .739 5. Delta nlne, Utah, Reolculated to 100 after deductlon of 7. 0.1 Cao as gypsm and 4.39 lnsoluble (sl0z,Al203,Fe203). !l.ll. nine, Happy,lack Fruits, utah ,lun lto, analyst. Utnh nlne, Utah (H€ss1924) 6. sam. Less pure sdple. Recalculated to 100 after deduction o 1.634 1.629 1.630 of 6.62 lnsoluble. Jun Iio, analyst. B 1.687 I .685 't.7391.689 Y 1.735 BlilJal negative,2tl about80'. P'leochrclcwlth .trcolorless, description, however, was obtained only after J pale y€llox, z rel lm. it had been synthesizedand analyzed (Table 5). The yellow color of sodium-zippeite contrasts with the golden yellow color of zippeite. The poraneous with the original material of J. F. optical properties of sodium-zippeite and zip- John (1821). peite are not materially altered by desiccation The X-ray powder data, optical properties over CaCl, or by exposure to air saturated with and chemical analyses of natural and synthetic water. There are no changes in the optical zippeite are given in Tables I, 2 and, 3. The characters of sodium-zippeite on heating to NHr member of the group has an almost 61'C; at 101oC, about O,SVoHrO is lost, the identical X-ray pattern and slightly higher in- indices of refraction increase (q. 1.666 B 1.7L2' dices of refraction than the K member, zip- y 1.770) and the X-ray pattern becomesslightly peite. The reported optical and X-ray data in- diffuse. dicate that both phases are represented among A notable locality is at the Happy Jack mine the numerou$ earlier reported synthesesof hy- in White Canyon, San Juan County, Utah, where drated uranyl sulfates using KOH or NHOH it occurs abundantly with other members of as precipitants. The direct water determinations the group as efflorescenceson the mine walls; reported for such material are higher (lO-13% also at the Delta mine, in the southwesternpart HzO) than that found here. of the San Rafael Swell, Emery County, Utah, In addition to the original occurrence at in part as cross-fiber veinlets; with andersonite Joachimsthal, where it occurs with gypsrn, at the Atomic King mine, Cane Springs, Moab uranopilite, johannite and other members of County, Utah. Other proven localities, all in the zippeite group, we have identified zippeite Utah, include the Oyler mine, Henry Mountains from the following localities: Great Bear Lake, district, Wayne County; the Lucky Strike No. 2 Canadaoassociated with liebigite and uranopilite mine, Emery County; the Parco No. 23 mine, [this material is different from that called, zip- Grand County; the Soda Roll mine, Green peite by Palache & Berman (1933), which prob- River district. San Juan County; and the W. M. ably was uranopilitel; at the Telegraph, Wood mine, Deer Flat, San Juan County. The min- and Kirk mines in Gilpin County, Colorado, eral from Fruita, Utah, analyzed by W. T. where it occurs with ill-defined zippeite-type Schaller (cited in Hess 1924) is sodium-zippeite. minerals containing Zn and Fe; at the Hillside Also found admixed in some specimens of mine, Yavapai County, Arizona, as one of sev- zippeite and of nickel-zippeite from Joachims- eral zippeite-type minerals; at the Besner mine, thal. Minerals described optically by Nov5dek Henvey Township, Ontario, as a coating on (1935) from Joachimsthal and by George (1949) thucholite; and as a coating on uraninite at from Gilpin County, Colorado, may be sodium- Schneeberg,Saxony. zippeite in part.

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The "zippeite" and zippeite-like minerals somewhat variable optical properties could not listed in many Atomic Energy Commission and be measured with precision. The color of the U.S. Geological Survey internal reports of the material varies from tan to brownish yellow and period 1950-1960 as occurring at numerous orange yellow. Traversing 1[e mine tunnels with mines and prospects in the Colorado Plateau a portable ultraviolet lamp afforded spectacular region and elsewhere probably are sodium-zip- views. peite in large part. Some of the earlier reported The fine-grained nature of the material nade optical and X-ray data, however, cannot be it impossibleto obtain pure samplesfor analysis. reconciled with any of the present descriptions. By means of X-ray fluorescence analysis, using standards made of the analyzed synthetic mem- CoseLrZrppEITE AND Ntcrrr--Zrppmtr bers, the Ni-Co atomic ratio was measured in 19 small hand-picked samples. The ratio was It was found experimentally that a complete found to range from approxirnately 4:1 to 1:3. solid solution series exists between the synthetic The ratio varied in material from different Co and Ni members. The X-ray powder spacings places in tle mine and also in successivelayers (Table 1) and the indices of refraction (Table in a single crust. The analyzed samples probably 6) of the end-compositions are virtually identical. representedmixtures of grains of different Ni- Co ratio in all instances. TASLE6. CHETICA!NAIYSES OF NICrcL-ZIPPEIIE AND COMI.T-ZIPPEIIE. Two complete wet-chemical analyseson com- M posite samples representing the material with nqo 0.54 0.56 Co)Ni and Ni>Co were obtained Cfable 6). F.0 0,70 0.57 t'fno 0.33 0,27 Further purification of these samples by sedi- tfto 6.0t 6,32 2,14 1.87 mentation techniques failed to remoYe admixed Coo 1.33 1.98 6.59 6.03 sodium-zippeite, as found by optical and X-ray u0: 69.09 68.4 66.1 67.2 67.8 69.07 examination. Considerable Mg, Fe and Mn are S0g 9.67 9.57 10.56 10.55 9.48 9.67 present in solid solution but Ni or Co are the H20 15.23 15.20 l8.l t7.0 15.46 15.23 dominant cations. The occupancy of the divalent Total 100.0099.49 [100.00][r00.00] 99.33100.00 percent in the two analyses o 1.745 1.73-1.74 1.747 (colorless) cation site in atomic s 1.777 1.76-1.77 1,779 (pale yellor) is (NiarCouaMgtrFerrMnu)and (CosNisnMgtFett '' y 1.84 1.82-1.83 l.g4 (yellil) Mn"). The observed variation in the indices of refraction of individual grains presumably re- l. Calcllatedfor Nl2(u0r)5(S04)3(0H)10.1 6HZ0 2. Sjmtheticnlckel-zlppelt6. ,runlto, an!lyst. flects variations in the amount and kind of the 3. Ilckel-zlppelte. Happylrack Elne, Utah. Recalculatedt! 100 substituting cations. aftef deductlngSl0Z 1.23, 4t2030.5, Tl02 0.08, (Ce,Y)2030.41, Nickel-zippeite free from admixture was 12.0 sodlm-zippelte,1.4 Johannlte. Jun lto, analyst. Joachims- 4. Cobalt-zlppelte. HappyJack nine, Utrh. Recalculatodto 100 identified in several specimensfrom after d€ductlngSl0A 0.80, 0.98 (Tt02,AlZ03.Ce203),9.0 thal. It had Ni:Co -10:3 and contained minor sodlm-zippelte, 1.6 Johannlt€. Jun Ito, analyst. Fe and Zn. The content of Ni and Co in this 5., Synth€tic cobalt-zlpp€lte. ,Junlto, anatyst. material derives from the smaltite-chloanthite 6. calculated for co2(u02)6(s04)3(0H) . I o.I 6H20 and nickeline in the uraninite veins. Ni and Co .i also were found as major constituents in zip- Zippeite-type material s6alnining Co, Ni, and peite-type minerals, too impure and small in other cations in widely varying ratios was amount for satisfactory study, from Great Bear abundant at one time at the Happy Jssft mine, Lake and Hottah Lake, Canada, and from the Emery County, Utah. Here the material oc- Hillside mine, Yavapai County, Arizona. These curred as extensive coatings on the mine walls all had Ni in excessof Co. associated with sodium-zippeite, uranopilite, johannite and zeunerite together chalcan- with MlcNrsruru-Zwpnrcn thite, antlerite, siderotil, bieberite, erythrite, epsomite and gypsum. The primary uraninite This mineral was found as a fine-grained ores at the mine (Trites et al, L959) were locally efflorescence in workings of the Lucky Strike rich in gersdorffite and unidentified CoNi min- No. 2 mine in Emery County, Utah. It occurs erals, from which the Co and Ni were derived, very sparingly, associatedwith sodium-zippeite, together with pyrite, chalcopyrite, bornite and gypsum, bieberite, cobaltocalcite and rabbiftite. sphalerite. The rnineral was originally found by M. E. The Co-Ni-zippeite solid solutions are in- Thompson, A. W. Weeks and A. M. Sherwood* timately admixed with sodium-zippeite and johannite together with finely divided elayey material. They are also relatively fine-grained, as 'r'Priority for the recopition and description of this minute shreds and petal-like crystals; and the new mineral belongsto theseauthors.

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but because of understandable uncertainties as TABLE 7. CHEMICA!NAI.YSES OF ZII{C-ZIPPEITE to its true identification at that time, it was not '1. mentioned in theh account o1 fis mineralogy of NaZo 0.12 the mine published h 1955. Zn0 7.01 3.4 A microchemical analysis by A. M. Sherwood t{90 0.87 uor 68.71 67.33 69.10 on a hand-picked 12 mg sample gave MgO 6.2, so3 oot o40 CoO 1.4, UOs 74,6, SO" 5.0, ItO 10.9, total H2o 15.85 14.26 98.1. The ratios of the analysis are not close Rm. to the formula for the zippeite group, but the t00.00 l0o.oo 101.m identification ef tls mineral as the Mg member a 1.72 1.70-1.715 (colorless) thereof is established by the X-ray powder data B 1.77 1.75-1.763 (paleye'llor) I .81 >1.7 (yellO) (Table 1). Co substitutes for Mg to a small ex- Y tent. Mg also is a significant constituent of the 1. Calculated for Znr(U02)5(S04)3(01)l0.I 5H20 cobalt-zippeite 2. Snthetlc mterla'|. Jun Ito, analyst. and nickel-zippeite from the 3. Hlllslde nlne, Adzona. Mlcrcchen.anal. on 1.050ng sanple,by Happy Jack mine. A complete series may ex- F.S.Crlro'Idl. Rem.ls lnsoluble2.1. Pbol.6, tend between the Mg-Co-Ni members. The natural material has an orange yellow to orange containing both Zn and Fe that is similar to tan color but the synthetic material is yellow. material from Gilpin County, Colorado, de- Synthetic magnesium-zippeite was too fine- ssribed below; also present are one or more fine- grained for satisfactory optical study it has grained yellow minerals with relatively low in- q. nl.'l0, F -1.74, f -L79. The natural ma- dices of refraction, q 1.61-1.65, aud dark terial examined here has slightly higher indices orange to brownish orange materials containing of refraction, with c I.72 (pale yellow), 'variedB 1.75 IvIn, Fe and Ni in variable amounts. (yellow), y 1.82 (dark yellow), that slightly in different specimens probably due to Fe2+. Mns+ eNo Cu MEMBERS variation in the Mg-Co ratio. Earlier-reported optical and X-ray data apparently represent a Repeated efforts to syntlesize the Fez* men- mixture with sodium-zippeite. The synthetic ber of the group yielded extremely fine-grained preparations all contain small amounts of op- precipitates, unsuited for optical study, that at tically amorphous foreign (?) material and no best gave very faint and diffuse X-ray patterns chemical analysis was made. of the zippeite-type. A suite of zippeite-type minerals from uraninite vein occurrences in ZNc-ZppBrrs Gilpin County, Colorado, probably includes the more or less oxidized Fe member of the zippeite The X-ray powder data (fable 1) and op- group. When uraninite was first recognized in properties tical of synthetic zinc-zippeite verify Colorado in 1871 at the Wood mine in Gilpin the unpublished description of a zinc uranyl County, it was noted by Pearce (1895) that sulfate found by Dr. Charles Miltont in speci- some specimens were coated by a "uranium mens from the Hillside mine, near Bagdad, vitriol", formed by oxidation of the pyritic ore, Yavapai County, Arizona. ft occurs with so- which consisted of johannite (gilpinite) together dium-zippeite and other zippeite-type minslatg with a golden brown to apricot mineral. The yellow, as orange and reddish brown coatings Iatter was later described optically and salled on quartzose ore containing disseminated sul- uraconite by Larsen (1921) and George (1,949). fides and uraninite. Associated minerals include Similar material occurred at tle Kirk, Tele- johannite, schroeckingerite, gypsum and bay- graph and Calhoon mines. Specimensexamined (Axelrod leyite et aI. 1951). The analyzed ma- here showed typical rhomboidal, petal-like and (Iable terial 7) is yellow and gives an X-ray spindle-shapedcrystals. The material is optically pattern identical with that of synthetic material. inhomogeneous and variable, probably caused We also have identified this mineral in more by alteration of a single phase in some in- recent specimens from the Hillside mine. It stances, but usually representing a mixture of forms shreds and minute curved crystals; the 'related phases. Many grains are mottled or optical properties (Table 7) are somewhat rimmed by alteration products. Spectrographic variable. Several other zippeite-type minerals examination of hand-picked samples showed occur at the locality. These include a more or either Fe or Zn as the dominant cation; minor less altered brownish yellow to brown mineral cations included Mg, Mn, Ni and Cu. Optically most of the samplesare in the range cr 1.71-1.74 (pale yellow), p t.77-1.80 (yellow), y I.84- tData zupplied by Dr. Milton. Priori$ for tfre 1.86 (golden). Larsen (1921) ga'te a 1.75, recognition of this new mineral belongs to him. P 1.79,7 1.85 with 2V medium. A samplewith

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Zn much in excess of Fe had a about 1.71. The X-ray pattems are very poor and variable, "HiI"fr"X#.*'s;"#;.*:l flrF8' "fr: but resemble those of the Co-Ni members. Both 472. zippeite and sodium-zippeite occur witl this johannite. Mineralogie, Vienna. material together with HEss, F. 1,. (tgZq: New and known minerals from The Mn"+ member of the group has been the Utah-Colorado carnotite regson',aJ. Geol' synthesized but has not been identified in na- Surv.Ball.750-D. tural material. The X-ray data are given in Jonrrr,J. F. (1821): ChemischeunGrsuchung eines Table 1. The indices of refraction arc q, t.73, nuii.itlichen Uranvitriols: Chem. Untersuch, 5, 1.78, y 1.83. Mn was found by optical or 254; Chem.Phys. 32' 248, P Maximilian X-ray sp-ectrography to be a ninor or trace Kernren, R. (1963): Frantiiek Xavier Geol. 4, constituent in numerous natural samples, es- Z.rppe (179I-18$). enopis Mineral, pecially the Hillside minen 2bi2qaa, fhe 404405. from reniiN,-E. S. (1921): The microscopicdetermina- mine, County' Happy Jack Utah, and Gilpin tion of the non-opaqueminerals. US. Geol. Surv' Colorado. Bull.679. The name cuprozippeite has been grven by Nov6dek, R. (1935): Study on some secoudary Boldyrev (1935) to a mineral ssalaining 5Vo uranium minerals. deske Spol. Nauk, Vestnik CuO but it is not known if the substance be- Kral., No. 7, CIz. longs in the zippeite group. Efforts to synthesize PAildi; e.' & BBRMAN,H. (1933): Oxidation Bear Lake. the Cu member of the group failed, johannite products of pitchblende from Great or basic copper sulfates being obtained together Amer, Mineral. 18, 20-24. R. (1895): Some occurrencesof uraninite sodium-zippeite or zippeite. Prancr, with in Colorado.Proc. Colorado,Sci.Joc. 5, 156-158. TtroMpsoN, M. E., Wners, A. D. & Smnwoop, REFBRENCES A. M. (1955): Rabbittite, a new uranium car' Amer. Mineral. 40' 20l'206. Mn-rox, C. & bonate from \)tah. A)cLRoo, J. M., Grrnaer,or,F. S., (1952): Synthesisand X-ray study of (1951): The uranium minerals TRATLL,R. J. MnRATA,K. J. uranium sulfate minerals. Amer. Minzral. 87" from the mine, Arizona. Amer. Mineral. Hilside 394-406. 36, t-22. Lovenrtcq T. G. (1935): TRrrEs, A. F., Cmw, R. T. & BoLDyREv,A. I( Kurs Opisatelnoi Mtnera' the uranium deposil at part (1959): Mineralogy of /ogCi.I$ingra4 3. Jack mrne, San Juan County, Utal. Fnorsort, (1958): Systematic mineralogy of the Happy C. U.S. Geol. Surv. Prof, Pap.320' 185'195. uranium and thorium. AS. Geol. Sum. BalL Wssrs, A. D. & TsolrPsoN, M. E. (1954): Identi' 1064. uranium and vanadium (1949): and fication and occurrenceof GEoRGE,D'A. Mineralogy of uranium the Colorado Plateau. U.S. Geol' U.S. Atorntc Energy minerals from thorium bearing minerals. Bull. 1009-8. Comm. RMO-563. Surv. GruNaR, J. W., Genmrrn, L. & Surtg, D. trL (1954): IIS. Atomic Energy Comm, RMn'8092. Manuscript receivedlune 1976.

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