American Mineralogist, Volume 82, pages 1261±1264, 1997

New names*

JOHN L. JAMBOR1 AND ANDREW C. ROBERTS2

1Department of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada 2Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0G1, Canada

Chrombismite* conchoidal , extremely brittle, perfect {101}Å cleav-

Xinchun Zhou, Jincai Yan, Guanxin Wang, Shizhong Wang, age, H ϭ 2±2½, VHN10 ϭ 38±51, red internal re¯ection, 3 Liang Liu, Guiming Shu (1997) Chrombismite, Bi16CrO27, twinned on (010) and (100), Dcalc ϭ 5.24 g/cm for Z ϭ 4. a new mineral species from the Jialu mine, Shaanxi Clearly visible anisotropy in re¯ected light; re¯ectance per- Province, China. Can. Mineral., 35, 35±38. centages in air (WTiC standard) at 470, 543, 587, and 657 Electron microprobe analysis (average of 15) gave Bi nm are 29.7±35.4, 28.8±33.1, 26.7±30.3, and 26.6±29.9, 87.23, Cr 1.35, O 11.27, sum 99.85 wt%, corresponding respectively. Single-crystal X-ray study indicated mono- to Bi3ϩ Cr6ϩ O . Valences of Bi and Cr were determined clinic symmetry, space group P21/n; a ϭ 8.121(3), b ϭ 16.006 0.997 27 Ê by XPS. The mineral occurs as columnar to acicular crys- 23.969(9), c ϭ 5.847(3) A, ␤ϭ107.68(3)Њ as re®ned from tals up to 25 ϫ 50 ␮m, and as irregular to spherical ag- a powder pattern (114 mm Debye±Scherrer, FeK␣ radia- tion) with strongest lines of 3.998(74,060), 3.816(54,210, gregates up to 1.5 mm across. Orange to yellowish-brown Å color, brownish-yellow , adamantine luster, translu- 3.587(86,221), 2.823(100,116), 2.778(84,260), and 2.670(58,301).Å cent, VHN100 ϭ 113.3 (95.8±128.0), brittle, no , 3 The mineral is associated with orpiment, realgar, and Dmeas ϭ 9.80(3), Dcalc ϭ 9.85 g/cm for Z ϭ 2. Optically uniaxial positive, ⑀ϭ2.55(2), ␻ϭ2.50(2), weakly pleo- other Tl-As sulfosalts in cavities in Triassic dolomite at chroic. Gray to light orange in re¯ected light, orange in- the Lengenbach quarry. The new name is for Franz ternal re¯ection, weak bire¯ectance and anisotropy. Te- Jentsch (1868±1908), head of a syndicate that was in the tragonal symmetry, space group I4, I4ÅÅ,orI4/m, a ϭ forefront of the exploitation of mineral specimens from 8.649(3), c ϭ 17.24(1) AÊ . Strongest lines of the powder the quarry. Type material is in the Natural History Mu- pattern (57 mm Debye±Scherrer, FeK␣) are 3.19(100,123), seum of Basel, and in the Mineralogical Institute, Uni- 2.730(40,310), 1.980(40,316), 1.715(30,219), and versity of Basel, Switzerland. 1.655(55,503,433), in good agreement with data for the Discussion. An incomplete description that focused on synthetic analog. the structural differences between jentschite and edenhar- The mineral occurs as a primary phase associated with terite was abstracted in Am. Mineral., 82, 431±432 pyrite, chalcopyrite, and gold in mesothermal quartz veins (1997). J.L.J. at the Jialu gold mine in Luonan County. The new name refers to the main elements present in the mineral. Type Jùrgensenite* material is in the Geological Museum of China, Beijing. J.L.J. H. Pauly, F.C. Hawthorne, P.C. Burns, G. Della Ventura (1997) Jùrgensenite, Na2(Sr,Ba)14Na2Al12F64(OH,F)4,a new alumino¯uoride mineral from Ivigtut, Greenland. Can. Mineral., 35, 175±179. Jentschite* S. Graeser, A. Edenharter (1997) Jentschite (Tl- Electron microprobe analysis gave Al 10.97, Mg 0.38,

PbAs2SbS6)Ða new sulphosalt mineral from Lengen- Ca 0.28, Sr 32.76, Ba 8.63, Na 3.25, K 0.30, F 42.50, H2O bach, Binntal (Switzerland). Mineral. Mag., 61, 131± (calc.) 1.22, sum 100.29 wt%, which for Al ϭ 12 corre-

137. sponds to (Na1.54Mg0.46)⌺2.00 (Sr11.03Ba1.85Na0.63K0.23Ca0.21)⌺13.95- Na Al F (OH) . The mineral occurs as fan-shaped Electron microprobe analyses (mean of 15) gave Tl 2.00 12 66.00 2.00 aggregates up to 2 mm across, and as grains up to 10 mm 23.92, Pb 21.44, As 19.16, Sb 12.53, S 22.42, sum 99.47 across, elongate [010], white color and streak, vitreous lus- wt%, corresponding to Tl Pb As Sb S . Occurs as 1.00 0.87 2.22 0.87 6.03 ter, brittle, H 3 ±4, no cleavage or parting, uneven frac- prismatic, platy to acicular, polysynthetically twinned crys- ϭ ½ ture, non¯uorescent, D ϭ 3.89(1), D ϭ 3.94 g/cm3 for tals, up to 2 mm long, showing major {010} and {130}, meas calc Z 1. Colorless in transmitted light, biaxial negative, and minor {001}, {041}, {101},ÅÅ {121}, and {151}. Å Bril- ϭ ␣ ϭ 1.436(1), ␤ϭ1.442(1), ␥ϭ1.442(1), 2V ϭ 0±5(5)Њ, liant black color, black metallic to submetallic luster, dark meas 2V ϭ 0Њ, Y ϭ␤, no dispersion. Single-crystal X-ray red streak, translucent red in thin fragments, uneven to calc structure study indicated monoclinic symmetry, space * Before publication, marked with an asterisk were group C2/m; a ϭ 16.046(1), b ϭ 10.971(1), c ϭ 7.281(1) approved by the Commission on New Minerals and Mineral AÊ , ␤ϭ101.734(6)Њ as re®ned from a Guinier powder pat- Names, International Mineralogical Association. tern (CuK␣) with strongest lines of 7.844(80,200), 3.643 0003±004X/97/1112±1261$05.00 1261 1262 JAMBOR AND ROBERTS: NEW MINERAL NAMES

ÅÅ (90,311), 3.453(100,112), 3.193(100,420), 3.112(90,421), 0.54), Cl 4.67 (3.84±5.74), H2O (loss on heating) 14.5, 2.998 (50,330), 2.989(90,022), 2.220(80,441),Å 2.173 O ϵ Cl 1.05, sum 100.68 wt%, corresponding to Å (90,150), and 2.001(80,801). Na0.90K0.05Ca0.23Cu2.79(AsO4)2.07Cl0.81´4.91H2O. Occurs as The mineral is associated with jarlite and stenonite in blue to emerald green aggregates of thin (ϳ0.1 mm) ®ssures in the main cryolite mass at Ivigtut. The new square crystals, and as spherules to 0.2 mm in diameter. name is for Vilhelm Jùrgensen (1844±1925), co-founder Crystals are tabular on {001}, showing also {100}. Vit- of the cryolite factory at Ivigtut. Type material is in the reous luster, translucent, pale blue streak, irregular frac- Geological Museum, University of Copenhagen, Den- ture, perfect {001} cleavage, H ϭ 2±3, non¯uorescent, 3 mark. J.L.J. Dmeas ϭ 3.33(2), Dcalc ϭ 3.36(1) g/cm for Z ϭ 8. Optically uniaxial negative, ␻ϭ1.686(2), ⑀ϭ1.635(2); intensely pleochroic, O ϭ blue to intense green-blue, E ϭ clear Juabite* blue to clear green. Single-crystal X-ray study indicated

A.C. Roberts, R.A. Gault, M.C. Jensen, A.J. Criddle, E.A. tetragonal symmetry, space group P42212; a ϭ 10.085(2), 6ϩ 5ϩ Ê Moffatt (1997) Juabite, Cu5(Te O4)2(As O4)2´3H2O, a c ϭ 23.836(8) A by re®nement of the powder pattern (114 new mineral species from the Centennial Eureka mine, mm Gandol®, CuK␣ radiation), with strongest lines at Juab County, Utah. Mineral. Mag., 61, 139±144. 11.90(100,326), 9.29(60,228), 7.132(50,219), 5.043 (60,424), 3.098(80,523), and 3.061(70,506). Three electron microprobe analyses gave CuO 38.25 The mineral is an oxidation product associated with (38.11±38.48), PbO 0.57 (0.41±0.74), TeO 32.58 3 tennantite, covellite, geminite, and pushcharovskite on (32.44±32.75), As O 22.81(22.48±23.04), H O (calc. for 2 5 2 quartz gangue. The new name is for V. Mahnert, director 3H2O) 5.19, sum 99.40 wt%, corresponding to 6ϩ 5ϩ of the Natural History Museum of Geneva, which is the (Cu5.01Pb0.03)⌺5.04(Te O4)1.93(As O4)2.07´3H2O. The infrared Ϫ1 repository for the type material. J.L.J. spectrum has a strong band for H2O at 3283 cm and a weaker band at 1642 cmϪ1. The mineral occurs as emerald green, platy masses (Ͻ1 mm across) in which the crystals Sheldrickite* average 125 ϫ 100 ϫ 1±2 ␮m, showing {010} and minor Å J.D. Grice, R.A. Gault, J. Van Velthuizen (1997) Sheld- {100}, {101}, and {101}. Translucent to transparent, vit- rickite, a new --¯uorocarbonate mineral reous luster (adamantine on crystal faces), pale green species from Mont Saint-Hilaire, Quebec. Can. Min- streak, brittle, uneven to subconchoidal fracture, perfect eral., 35, 181±187. {010} cleavage, H ϭ 3±4, non¯uorescent, D ϭ 4.59 calc Electron microprobe analysis gave Na O 9.16, CaO g/cm3 for Z ϭ 2. White in re¯ected light, with ubiquitous 2 48.84, SrO 0.36, F 16.17, CO (calc.) 25.81, H O (TGA) turquoise-blue internal re¯ections. Single-crystal X-ray 2 2 5.61, O ϵ F 6.81, sum 99.14 wt%, corresponding to study indicated triclinic symmetry, space group P1or Na (Ca Si ) (CO ) [F (OH) ] ´H O, ideally P1Å;aϭ8.984(5), b ϭ 10.079(7), c ϭ 8.975(5) AÊ , ␣ϭ 1.01 2.97 0.01 ⌺2.98 3 2 2.90 0.07 ⌺2.97 2 NaCa (CO ) F ´H O. Occurs as a colorless to white ag- 102.68(7), ␤ϭ92.45(6), ␥ϭ70.45(5)Њ as re®ned from 3 3 2 3 2 gregate of blocky crystals up to 2 mm wide, with indi- the powder pattern (114 mm Debye±Scherrer, CuK␣ ra- vidual crystals up to 0.1 mm, and as aggregates of silky diation) with strongest lines of 9.28(70,010), 4.65 white ¯akes to 2 mm across. Vitreous luster, white streak, (70,020), 3.097(100,030,211),Å 3.018(60,212), 2,658 brittle, uneven fracture, H ϭ 3, good {001} parting, non- (50,301),ÅÅÅÅÅÅÅ 2.468(50,222), and 1.740(50,115,521,151). ¯uorescent, D ϭ 2.86(4), D ϭ 2.86 g/cm3 for Z ϭ The mineral occurs on drusy quartz in vugs in a single meas calc 3. TGA showed H O loss in one continuous step between specimen from the dumps of the Centennial Eureka mine, 2 160±265 ЊC. Strong infrared absorption bands for O±H Juab County, Utah. The new name refers to the type lo- and CO occur at 3376 and 1464 cmϪ1, respectively. Op- cality. Associated minerals are enargite, beudantite, and 2 tically uniaxial positive, ␻ϭ1.538(2), ⑀ϭ1.563(4). Sin- the possible Pb analog of arsenobismite. Type material is gle-crystal X-ray structure study (R ϭ 0.046) indicated in the Systematic Reference Series of the National Min- trigonal symmetry, space group P3 ; a ϭ 6.718(3), c ϭ eral Collection housed at the Geological Survey of Can- 2 15.050(4) AÊ from indexing of a Gandol® powder pattern ada, Ottawa, and in The Natural History Museum, Lon- (114 mm camera, CuK␣ radiation) with strongest lines of don, UK. J.L.J. 2.791(50,113), 2.508(40,006), 2.010(100,116,213), and 1.939(40,300). The mineral is associated with shortite, , mi- Mahnertite* crocline, polylithionite, , , , H. Sarp (1996) Mahnertite, (Na,Ca)Cu3(AsO4)2Cl´5H2O, ¯uorite, and several other minerals that are thought to be a new mineral from the Cap Garonne mine, Var, late-stage hydrothermal products in a marble xenolith in France. Archs Sci. GeneÂve, 49(2), 119±124 (in French, English abs.). nepheline syenite at the Poudrette quarry, Mont Saint- Hilaire, Rouville County, Quebec. The new name is for Nine electron microprobe analyses gave CuO 36.37 G.M. Sheldrick (b. 1942) of the University of GoÈttingen.

(35.04±37.78), As2O5 39.07 (38.05±40.58), Na2O 4.58 Type material is in the Canadian Museum of Nature, Ot-

(3.95±5.33), CaO 2.14 (1.70±2.73), K2O 0.40 (0.21± tawa, J.L.J. JAMBOR AND ROBERTS: NEW MINERAL NAMES 1263

Ru-Os-Ir, Ru-Ir-Pt, Pt3Cu, Rh2As, (Ru,Rh)(Te,Sb)2, RuO2(?) RuO 2 One of two analyses of ®ne-grained pseudomorphs af-

S. TrsticÂ, M. Tarkian (1997) Platinum-group minerals in ter laurite gave RuO2 74.62, FeO 10.39, HgO 10.96, OsO2 gold-bearing placers associated with the VelucÂe ophiol- 1.81, IrO2 3.35, sum 101.13 wt%, possibly corresponding ite complex, Yugoslavia. Can. Mineral., 35, 1±21. to RuO2, with Hg likely a contaminant from amalgama- tion. In re¯ected light, dark gray with a brownish tinge, Platinum-group minerals recovered from stream and strongly bire¯ectant and anisotropic. terrace sediments along the Srebrenica River and its trib- Discussion. For another reported occurrence of Ru ox- utaries were derived from the VelucÂe ophiolite complex ide or hydroxide, see Am. Mineral., 80, 847±848 (1995). in central Serbia, Yugoslavia. Electron microprobe anal- J.L.J. yses indicate that the following new or unusual PGM are present.

(Ir,Os)Te2, (Ir,Os)(S,As,Te)2, (Ir,Os)(As,Te), Ir-Ru-Os alloy (Ir,Os)(Te,As), (Ru,Ir,Os)Te Analysis gave Pt 12.39, Ir 50.08, Os 16.97, Ru 12.91, N. Tolstyk, A. Krivenko, L. Pospelova (1997) New com- Rh 6.64, Fe 0.42, Cu 0.44, and Pd, Ni, As, Sb Ͻ0.10, pounds of Ir, Os and Ru with selenium, arsenic and tellurium. Eur. J. Mineral., 9, 457±465. sum 99.85 wt%, corresponding to Ir0.42Ru0.21Os0.14Rh0.10- Pt0.10Fe0.01Cu0.01. In the system Ru-Os-Ir, the composition A heavy-mineral concentrate from alluvium of the Zo- falls within the purported miscibility gap between lotaya River in western Sayan, Russia, contains magne- and . The mineral occurs as a discrete tite, hematite, ilmenite, , Os-Ir-Ru and Pt-Fe al- grain, and as exsolution lamellae and blebs in a grain of loys, Se-bearing , tetra-auricupride, Se-rich Pt-Fe alloy. iridarsenite(?), and the following PGM analyzed by elec- tron microprobe. The PGM were derived from serpentin- Ru-Pt-Ir alloy ized hyperbasites. Analysis of exsolution blebs within a Pt-Fe alloy gave (Ir,Os)Te Pt 49.28, Ir 13.25, Os 4.06, Ru 28.70, Rh 3.99, Fe 0.47, 2 Cu 0.32, sum 100.07 wt%, corresponding to Analysis gave Ir 26.56, Os 15.55, Ru 0.59, Pt 0.17, Rh 0.36, Cu 0.15, As 2.93, Te 50.01, S 0.04, Se 1.84, sum Ru0.42Pt0.37Ir0.10Rh0.06Os0.03Fe0.01Cu0.01. The composition is within the unnamed, Ru-rich part of the system Ru-Pt-Ir. 98.20 wt%, corresponding to (Ir0.60Os0.36Ru0.03Rh0.01Cu0.01)⌺1.01 (Te1.71As0.17Se0.10S0.01)⌺1.99. Occurs as a thin rim on a grain of (Ir,Os) alloy. Light gray color, anisotropic. Pt3Cu Analysis gave Pt 85.98, Ru 0.26, Rh 0.35, Fe 0.21, Cu

11.82, Ni 0.43, sum 99.05 wt%, corresponding to (Ir,Os)(S,As,Te)2 (Pt2.74Rh0.02Ru0.02)⌺2.78(Cu1.16Ni0.04Fe0.02)⌺1.22, possibly Pt3Cu Analysis gave Ir 38.65, Os 21.30, Ru 0.25, Pt 1.16, Rh (Am. Mineral., 78, 1110±1111, 1993). Occurs as an an- 0.15, Cu 0.90, Fe 0.11, As 12.53, Te 6.74, S 15.00, Se hedral grain 130 mm across, and as exsolution blebs and 0.26, sum 97.05 wt%, corresponding to (Ir0.59Os0.33Cu0.04- rods in Pt-Cu-Sb alloy. Ru0.01Pt0.01Rh0.01Fe0.01)⌺1.00(S1.36As0.49 Te 0.15)⌺2.00. Occurs as an inclusion in (Ir,Os) alloy. Rh2As (Ir,Os)(As,Te) One of three analyses listed gave Pt 0.49, Rh 60.81, Pd 12.65, As 26.04, sum 99.99 wt%, corresponding to One of four analyses gave Ir 45.35, Os 19.49, Ru 1.78, Pt 0.39, Pd 0.37, Cu 0.52, As 11.87, Te 17.48, S 1.29, Se (Rh1.67Pd0.34Pt0.01)⌺2.02As0.98. In re¯ected light, pale brown- ish gray with a green tinge, distinct bire¯ectance, mod- 1.06, sum 99.60 wt%, corresponding to (Ir0.65Os0.28Ru0.05- erately to strongly anisotropic. Numerous grains of the Cu0.02Pd0.01Pt0.01)⌺1.02(As0.45Te 0.38S0.11 Se0.04)⌺0.98. Occurs as a mineral are present, and size is up to 120 ϫ 150 ␮m. veinlet 10 mm wide in a grain of (Ir,Os) alloy. Gray color in re¯ected light, weakly anisotropic. (Ru,Rh)(Te,Sb) 2 (Ir,Os)(Te,As) Analyses of a subhedral grain 45 ϫ 75 mm, and of a Analysis gave Ir 39.55, Os 23.35, Ru 0.25, Pt 0.22, Rh grain intergrown with Pt-Fe alloy, gave Ru 12.73, 13.41, 0.16, Cu 0.23, As 8.90, Te 19.49, S 0.41, Se 4.45, sum Rh 9.33, 8.79, Ir 5.90, 6.66, Pt 5.15, 4.15, Cu 0.11, 97.01 wt%, corresponding to (Ir0.60Os0.36Ru0.01Cu0.01- Ͻ0.10, Te 50.39, 51.92, Sb 9.60, 9.58, As 2.38, 2.11, Bi Pt0.01)⌺0.99(Te0.45As0.35Se0.17S0.04)⌺1.01. Occurs as a rim on 4.64, 3.76, sum 100.23, 100.38 wt%, corresponding to (Ir,Os) alloy.

(Ru0.47Rh0.34Ir0.11Pt0.10Cu0.01)⌺1.03(Te1.48Sb0.29As0.12Bi0.08)⌺1.97 (Ru,Ir,Os)Te and (Ru0.49Rh0.32Ir0.13Pt0.08)⌺1.02(Te1.51Sb0.29As0.11Bi0.07)⌺1.98.In re¯ected light, gray with a brownish tinge; isotropic, with Two analyses gave Ir 19.66, 12.66, Os 15.46, 12.60, re¯ectance slightly higher than that of laurite. Ru 15.01, 24.21, Pt 0.74, 0.78, Rh 1.10 , ±, Cu 0.17, 1264 JAMBOR AND ROBERTS: NEW MINERAL NAMES

0.31, Fe ±, 0.26, As 0.32, ±, Te 46.47, 42.33, S ±, 0.07, 2.964(100,222), 1.814(55,440), and 1.548(50,622). The Se 0.19, 2.61, sum 99.12, 95.83 wt%, corresponding to mineral occurs in braunite-rhodonite bedded Mn ore at the

(Ru0.41Ir0.28Os0.23Rh0.03Pt0.01Cu0.01)⌺0.97(Te1.01Se0.01As0.01)⌺1.03 Gozaisho mine, Fukushima Prefecture. The ideal formula and (Ru0.64Os0.18Ir0.18Pt0.01Fe0.01)⌺1.02(Te0.89Se0.09S0.02)⌺0.98. Oc- of romeÂite is suggested to be NaCaSb2O6(F,OH). curs as a rim on , and as veinlets in Os-Ir-Ru Discussion. The formula of romeÂite is conventionally alloy. Grayish white in re¯ected light, re¯ectance similar written with Ca rather than Na, and OH rather than F to that of the host alloy, isotropic. predominance. Clari®cation of the formula of romeÂite, Discussion. See also Am. Mineral., 78, p. 673 (1993) and of the validity of lewisite vs. romeÂite, is required. for an abstract on (Ir,Pt,Rh)S2 from another locality. J.L.J. J.L.J.

Ag0.66Pb0.88Bi0.1Sb1.33S4 New Data J. MartõÂnez-FrõÂas (1996) The Congostrina mine: A unique Afghanite case of Bi- and Sb-rich sulphosalt association in the Hiendelaencina mining district (Spain). Neues P. Ballirano, E. Bonaccorsi, A. Marsas, S. Merlino (1997) Jahrb. Mineral. Mon., 377±383. of afghanite, the eight-layer member of the group: Evidence for long-range or- Electron microprobe analyses (15 listed) gave Ag dering. Eur. J. Mineral., 9, 21±30. 10.27±10.88, Pb 24.98±26.20, Sb 21.00±22.32, Bi 24.33± Single-crystal X-ray structure study (R 0.045) gave 25.10, S 16.98±17.77, sum 99.06±100.98 wt%, corre- ϭ a 12.8013(7), c 21.4119(18) AÊ , and the new space sponding to Ag Pb Bi Sb S . The mineral occurs as ϭ ϭ 0.66 0.88 0.81 1.33 4 group P31c. Perfect Si,Al order lowers the symmetry homogeneous cores, up to 50 ␮m across, rimmed by frei- from P6 mc. J.L.J. bergite. In re¯ected light, pale green, nonpleochroic, no 3 internal re¯ection, isotropic. Re¯ectance and hardness are similar to those of . Associated minerals are mainly Mineral ``A'' galena, aramayoite, and friebergite, which occur in a quartz-barite-siderite gangue in epithermal veins. J.L.J. S.L. Korzeb, E.E. Foord, F.E. Lichte (1997) The chemical evolution and paragenesis of uranium minerals from the Ruggles and Palermo granitic pegmatites, New Hampshire. Can. Mineral., 35, 135±144. Na-dominant romeÂite E.E. Foord, S.L. Korzeb, F.E. Lichte, J.J. Fitzpatrick S. Matsubara, A. Kato, M. Shimizu, K. Sekiuchi, Y. Su- (1997) Additional studies on mixed uranyl oxide±hy- zuki (1996) RomeÂite from the Gozaisho mine, Iwaki, droxide hydrate alteration products of uraninite from Japan. Mineral. J., 18, 155±160. the Palermo and Ruggles granitic pegmatites, Grafton County, New Hampshire. Can. Mineral., 35, 145±151. Electron microprobe analysis gave Na2O 7.52 (7.07± 7.95), CaO 10.87 (10.51±11.25), MnO 0.24 (0.18±0.29), Chemical analysis, X-ray powder diffraction data, and

Sb2O5 78.21 (77.96±78.42), F 4.10 (3.88±4.38), O ϵ F other results (TGA, IR) indicate that mineral ``A'', ini-

1.73, H2O (by difference) 0.78, sum 100 wt%, correspond- tially described in Am. Mineral., 41, 539±568 (1956) as ing to (Na1.00Ca0.80Mn0.01)⌺1.81Sb2[O5.69F0.89(OH)0.36]⌺6.94. Oc- one of several minerals in ``gummite'', is an orange to curs as honey to brownish yellow octahedral crystals, up yellow-orange mixture that formed by hydrothermal al- to 4 mm, showing {111} and infrequent {311}. Vitreous teration of uraninite. The mixture consists of at least two to subadamantine luster, no cleavage, Dmeas ϭ 5.05(2), Dcalc uranyl oxide-hydroxide hydrates, one of which is a mem- ϭ 5.096 g/cm3 for Z ϭ 8. Single-crystal X-ray structure ber or members of the schoepite group, and the other of study (R ϭ 0.013) indicated cubic symmetry, space group which is similar to phases known only as synthetic com- Fd3m, a ϭ 10.265(2) AÊ . Strongest lines of the X-ray dif- pounds. The X-ray data for mineral ``A'' are closest to fractometer pattern are 5.933(45,111), 3.097(50,311), those for synthetic UO2.86´1.5H2O and UO2(OH)2. J.L.J.