In this issue

This New Mineral Names has entries for 5 new minerals, including cerchiaraite-(Al), cerchiaraite-(Fe), štěpite, vysokýite, and yaroshevskite.

Cerchiaraite-(Fe)*, Cerchiaraite-(Al)*

A.R. Kampf, A.C. Roberts, K.E. Venance, C. Carbone, D. Belmonte, G.E. Dunning, and R.E. Walstrom (2013) Cerchiaraite-(Fe) and cerchiaraite-(Al), two new barium cyclosilicate chlorides from Italy and California, USA. Mineralogical Magazine, 77(1), 69–80.

Cerchiaraite-(Fe) (IMA 2012-012), ideally Ba4Fe43+(Si4O12)O2(OH)4Cl2[Si2O3(OH)4], and cerchiaraite-(Al) (IMA 2012-011), ideally Ba4Al4(Si4O12)O2(OH)4Cl2[Si2O3(OH)4], are new minerals described from different locations. For the cerchiaraite-(Fe) type localities are the Cerchiara mine, Liguria, Italy and the Esquire No. 7 and No. 8 claims, Big Creek, Fresno County, California, USA. Cerchiaraite-(Al) was found at the Esquire No. 1 claim, Rush Creek, Fresno County, California, USA and at the Esquire No. 7 and No. 8 claims noted above. At the Cerchiara mine, cerchiaraite-(Fe) occurs as tan to brown thin prisms and matted fibers in small fractures and veinlets within the metacherts of a Jurassic ophiolitic sequence. It is associated with aegirine, calcite, Mn-bearing diopside (variety schefferite), hematite, K-feldspar, norrishite and quartz. The origin is related to re-equilibration of the ophiolitic sequences during tectonometamorphic overprinting (~80 Ma) in prehnite-pumpellyite facies conditions (P = 2–3 kbar, T = 250–300 °C). Cerchiaraite-(Fe) and cerchiaraite-(Al) from the Esquire No. 1, No. 7, and No. 8 claims occur in parallel-bedded quartz-sanbomite vein assemblages which formed as a result of fluid interaction along the margin of the vein. At the Esquire No. 1, No. 7, and No. 8 claims, both minerals occur as subparallel aggregates of blue to bluish green irregular prisms in subparallel crystal aggregates generally less than 1 mm across. Associated minerals at the Esquire No. 1 claim for cerchiaraite-(Al) include bazirite, diopside, goethite, opal, quartz, sanbornite, titantaramellite, traskite, and witherite. At the Esquire No. 7 claim, cerchiaraite-(Fe) and cerchiaraite-(Al) are associated with bazirite, diopside, muirite, pyrrhotite, Ba-rich tobermorite, traskite and witherite. At the Esquire No. 8 claim, they are associated with bazirite, calcite, diopside, pyrrhotite, titantaramellite, and Ba-rich tobermorite. Crystals of both minerals are transparent with a colorless to tan streak (Cerchiara mine) or pale green-blue streak (Esquire No. 1, No. 7, and No. 8 claims), have a vitreous luster, brittle tenacity, irregular fracture, show no cleavage and have a Mohs hardness of ~4½. The density could not be measured for cerchiaraite-(Fe) due to the fibrous nature of the crystals; Dcalc = 3.710 g/cm3. For cerchiaraite-(Al), Dmeas = 3.69(3) g/cm3,Dcalc = 3.643 g/cm3. The new minerals do not fluoresce in long-wave or short-wave ultraviolet light. Cerchiaraite-(Fe) is uniaxial (+), with ω = 1.741(2), ɛ = 1.768(2). It is weakly pleochroic with O (colorless) < E (yellow). Cerchiaraite-(Al) is uniaxial (–), with ω = 1.695(2) and ɛ = 1.677(2). It is strongly pleochroic with O (colorless) < and E (blue). The average of 10 electron probe WDS analyses of the cerchiaraite-(Fe) from the Cerchiara mine is [wt% (range)]: Na2O 0.05 (0.00–0.13), BaO 40.81 (39.13–42.08), CaO 0.17 (0.03–0.42), MgO 0.06 (0.00–0.13), Mn2O3 0.22 (0.04–0.46), Fe2O3 19.03 (18.25–20.26), Al2O3 0.87 (0.74–0.94), TiO2 1.51 (0.52–2.25), SiO2 23.51 (23.26–23.83), Cl 5.47 (5.13–5.98), O=Cl –1.23, H2O (by stoichiometry) 5.84. The empirical formula based on 27 anions pfu is (Ba3.82Na0.02Ca0.04)∑3.88 (Fe3+3.42Ti4+0.27Al3+0.25Mn3+0.04Mg0.02)∑4.00Si5.62O15.47(OH)9.31Cl2.22. The average of 11 electron probe WDS analyses on the cerchiaraite-(Al) from the Esquire No. 1 claim is [wt% (range)]: BaO 44.82 (43.75–46.91), MgO 0.43 (0.35–0.59), MnO 0.30 (0.20–0.44), Fe2O3 (total) 7.27 (5.58–8.25), Fe2O3 6.55 and FeO 0.65 (on the basis of bond-valence analysis), Al2O3 8.94 (8.12–9.79), SiO2 25.38 (25.25–26.22), Cl 7.53 (7.35–7.94), O=Cl –1.70, H2O (by stoichiometry) 5.76. The empirical formula based on 27 anions pfu is Ba4.00(Al3+2.40Fe3+1.12Mg0.15Fe2+0.12Mn2+0.06)∑3.85Si5.78O15.34(OH)8.75Cl2.91. The strongest lines in the X-ray powder-diffraction pattern of cerchiaraite-(Al) from Esq.1 [dobs (Å) (Iobs%; hkl)] are: 3.009 (100; 411,002), 2.580 (93; 501,222), 3.316 (77; 321), 1.880 (68; 213,532,730,721,602), 1.4031 (54; 941,723,912,950). The unit-cell parameters refined from powder-diffraction data are: a = 14.317(4), c = 6.0037(18) Å, V = 1230.6 Å3. Single-crystal X-ray diffraction data collected on a crystal of cerchiaraite-(Fe) from Esq.8 of size 70 × 40 × 40 μm refined to R1 = 0.0253 for 329 unique reflections with I ≥ 4σ(I) shows the new mineral is tetragonal, space group I4/mmm, with a = 14.3554(12), c = 6.0065(5) Å, V = 1237.80 Å3, and Z = 2. The new minerals are isostructural with cerchiaraite. Their structure consists of corner-sharing SiO4 tetrahedra that form 4-membered rings that link via corner-sharing to an edge-sharing chain of Fe3+O6 octahedra running parallel to c. A Cl site alternates along c with the Si4O12 ring. A large channel in the framework contains Ba atoms around its periphery and statistically distributed Si2O3(OH)4 silicate dimers and Cl atoms. The names are after cerchiaraite, where a suffix-based naming scheme is used and in which the original cerchiaraite is renamed cerchiaraite-(Mn). Five cotype specimens are deposited at the Natural History Museum of Los Angeles County, Los Angeles, California, U.S.A. O.C.G.

Štěpite*, Vysokýite*

J. Plášil, K. Fejfarová, J. Hloušek, R. Škoda, M. Novák, J. Sejkora, J. Čejka, M. Dušek, F. Veselovský, P. Ondruš, J. Majzlan, and Z. Mráek (2013) Štěpite, U(AsO3OH)2·4H2O, from Jáchymov, Czech Republic: the first natural arsenate of tetravalent uranium. Mineralogical Magazine, 77(1), 137–152.

J. Plášil, J. Hloušek, R. Škoda, M. Novák, J. Sejkora, J. Čejka, F. Veselovský, and J. Majzlan (2013) Vysokýite, U4+(AsO2(OH)2)4·4H2O, from Jáchymov, Czech Republic. Mineralogical Magazine, 77(8), 3055–3066.

Štěpite (IMA 2012-006), ideally U4+(AsO3OH)2·4H2O and vysokýite (IMA 2012-067), ideally U4+(AsO2(OH)2)4·4H2O are new natural arsenates of tetravalent uranium discovered at the intersection of the Geschieber and Geyer veins, 10th level of the Svornost (former “Einigkeit”) mine Jáchymov (St Joachimsthal) ore ditrict, Krušné Hory Mountains (Erzgebirge), ~20 km north of Karlovy Vary, NW Bohemia, Czech Republic. The Jáchymov ore ditrict is a classic example of Ag-As-Bi-Co-Ni-U hydrothermal vein-type deposit The new minerals were found on the surface of native arsenic lens (with traces of arsenopyrite and pyrite and with no uraninite) weathered by post mining processes being exposed to a moist environment for more than 40 years. The supergene association includes arsenolite (abundant), bĕhounekite, claudetite, kaatialaite, scorodite, parasymplesite, gypsum, picropharmacolite, melanterite, native sulfur and a partially characterized phase (H3O)2+(UO2)2(AsO4)2·6H2O. Štěpite was originally reported from Jáchymov as an unnamed new phase U4+(HAsO4)·4H2O (Ondruš et al. 1997) and it was subsequently codified as UM1997-20-AsO:HU at the IMA list of valid unnamed minerals.

Štěpite forms crystalline crusts of tabular crystals with prominent {001} and {010} faces, up to 0.6 mm in size, commonly intergrown to form aggregates up to 6 mm across. It also occurs as blocky intergrowths of crystals and as minute radiating aggregates of thin platy crystals. Crystals of štěpite are emerald-green with a gray to greenish gray streak and vitreous luster, have very good cleavage on (001), an uneven fracture, are brittle, and have a Mohs hardness of ~2. The density was not measured; Dcalc = 3.90 g/cm3. Štěpite is not fluorescent in either short-wave or long-wave ultraviolet light. It is nonpleochroic (color in transmitted light is not given), biaxial (–) with α = 1.636(2), β = 1.667(3), γ = 1.672(2), and 2Vobs < ~5°, shows anomalous interference grayish to pale yellow colors on the 001 plane. The wavenumbers of the main absorption bands of the IR spectrum (cm−1) are: 3457 and 3392 (OH-stretching vibrations of H2O and OH); 1652 [v2 (δ) bending vibration of H2O]; 1402 and 1236 [δ(As-OH) bending]; 1076, 1035, and 1004 (probably overtones); 936, 869, 853, 830, and 815 [overlapping bands of v(AsO3OH) stretching vibrations (v1 symmetric and split triply degenerate v3 antisymmetric vibrations)]; 758 [v(As-OH) stretching vibration]; 653 (possibly libration modes of H2O molecules); 559 and 425 [δ(AsO3OH) bending vibrations]. The wavenumbers of the main absorption bands of Raman spectrum (cm−1) are: 3552 and 3484 (OH-stretching vibrations of H2O and OH); 1641 [v2 (δ) bending vibration of H2O]; 1490 and 1239 [δ(As-OH) bending]; 896, 844, and 811 [overlapping v(AsO3OH) stretching vibrations (v1 symmetric and split triply degenerate v3 antisymmetric vibrations)]; 760 [v(As-OH) stretching vibration]; 420, 401, 377, 368, 351, 322, and 312 [δ(AsO3OH) bending vibrations]; 287, 262, and 235 [v(OH-O) stretching vibrations]; 180, 160, 139, 115, and 107 (lattice modes). The average of 6 electron probe WDS analyses is [wt% (range)]: Na2O 0.13 (0.08–0.19), UO2 (valence of U verified by XANES spectroscopy) 50.19 (49.71–50.63), SiO2 0.12 (0.09–0.20), P2O5 0.46 (0.29–0.51), As2O5 38.64 (37.41–39.73), SO3 1.95 (1.23–2.51), H2O (calculated on the basis of 4H2O + 2OH from the structure determination) 16.41. The empirical formula based on 12 O apfu is (U1.01Na0.02)∑1.03[(AsO3OH)1.82(PO3OH)0.04(SO4)0.13(SiO4)0.01]∑2.00·4H2O. The strongest lines in the X-ray powder-diffraction pattern [dobs Å (Iobs%; hkl)] are: 8.190 (100; 004), 7.008 (43; 112), 5.475 (18; 200), 4.111 (16; 008), 3.395 (20; 312,217), 2.1543 (25; 419). The unit-cell parameters refined from powder-diffraction data are: a = 10.9905(4), c = 32.782(2) Å, and V = 3959.7 Å3. Single-crystal X-ray diffraction data collected on a crystal of size 0.16 × 0.13 × 0.08 mm refined to R1 = 0.0353 for 1434 unique reflections with I ≥ 3σ(I) shows štěpite is tetragonal, space group I41/acd, with a = 10.9894(1), c = 32.9109(6) Å, V = 3974.5 Å3, and Z = 16. The structure of štěpite consists of sheets of eight-coordinate uranium atoms and hydroxyarsenate “tetrahedra” perpendicular to [001], with the uranium being bonded to six oxygen atoms which belong to the hydroxyarsenate groups and two oxygen atoms from interlayer H2O molecules. The UO8 polyhedra are connected to five other U polyhedra via six AsO3OH groups. The [U4+(AsO3OH)22+]0 sheets are linked by hydrogen bonds involving H2O molecules in the interlayers and OH groups in the sheets. The new mineral is named in honor of Ing. Josef Štěp (1863–1926), a Czech mining engineer who played a leading role in the development of the Jáchymov mines, and the “father” of the world’s first radioactive spa at Jáchymov.

Vysokýite forms rich, radial aggregates, consisting of light-green very fine, exceptionally long fibers (up to 8 mm) elongated on [010]. Crystals of vysokýite are occasionally covered by small aggregates of green tabular štĕpite crystals or their hemispherical aggregates and are associated with prismatic green crystals of bĕhounekite. Vysokýite has an alabaster luster and a greenish-white to grayish streak. It is brittle with uneven fracture and perfect cleavage along (100) and (001); the Mohs hardness is ~2. Density was not measured due to fibrous nature of the crystals; Dcalc = 3.393 g/cm3. The mineral does not fluoresce under short- or long-wave UV radiation. It is colorless in transmitted light (pleochcroism not mentioned). The refractive indices could be only measured along and perpendicular to fibres: α′ = 1.617(3), γ′ = 1.654(3) (589 nm). The estimated optical orientation is α′ ~ X, γ′ ~ Z. The Raman spectrum covering the range 50–3150 cm−1 shows bands (cm−1) at 2750 and 2230 (v O-H stretching vibrations of As-OH and of hydrogen-bonded H2O molecules; 1545 and 1435 (combination bands and/or overtones); highest intensity bands 920 and 816 (v3 antisymmetric and v1 symmetric As-O stretching); 769 (As-OH stretching); 595 and 559 (δ As-OH bending vibrations); 427, 368 [v4 (δ) O-As-O bending], 324 [v2 (δ) bending]; 200, 184, 99, and 61 (lattice modes). The average of 5 electron probe WDS analyses is [wt% (range)]: SiO2 1.03 (0.70–1.05), UO2 29.44 (24.50–32.05), As2O5 48.95 (46.29–50.99), SO3 0.12 (0–0.48), H2O 15.88 (by stoichiometry 4H2O+8OH from the crystal structure), total 95.42. The reason of the low total is not explained. The empirical formula based on 20 O apfu is U1.00[AsO2(OH)2]3.90(SiO4)0.16(SO4)0.01·4H2O. The strongest lines in the X-ray powder diffraction pattern are [dobs Å (Iobs%; hkl)]: 8.872(100; 100), 8.067 (50; 002), 6.399 (7; 103), 4.773 (6; 104), 3.411 (10; 302), 3.197 (18; 313). Single-crystal X-ray diffraction data collected on a crystal of size 0.19 × 0.02 × 0.01 mm refined to R1 = 0.0595 for 2718 unique reflections with I ≥ 3σ(I) shows vysokýite is triclinic, space group P1̄, with a = 10.749(2), b = 5.044(3), c = 19.1778(7) Å, α = 89.872(15)°, β = 121.534(15)°, γ = 76.508(15)°, V = 852.1 Å3, Z = 2. The crystal structure of vysokýite consists of UO8 square antiprisms sharing all of their vertices with 8 As-tetrahedra to form infinite chains parallel to [010]. These chains are linked by hydrogen bonds involving terminal (OH) groups of the double-protonated As-tetrahedra and molecules of H2O located between the chains. The new mineral is named in honor of Ing. Arnošt Vysoký (1823–1872), the former chief of the Jáchymov mines and smelters, chemist, metallurgist and specialist in technological processes of the ores.

The type specimens of štěpite and vysokýite have been deposited in the collections of the Department of Mineralogy and Petrology of the National Museum in Prague, Czech Republic. O.C.G., D.B.

Discussion

The calculated 2V for štěpite is 43°. Thus one of the measured values: 2V or refractive index β are incorrect. The mineral could be anomalously biaxial.

Yaroshevskite*

I.V. Pekov, N.V. Zubkova, M.E. Zelenski, V.O. Yapaskurt, Yu.S. Polekhovsky, O.A. Fadeeva, and D.Yu. Pushcharovsky (2013) Yaroshevskite, Cu9O2(VO4)4Cl2, a new mineral from the Tolbachik volcano, Kamchatka, Russia. Mineralogical Magazine, 77(1), 107–116.

Yaroshevskite (IMA 2012-003), ideally Cu9O2(VO4)4Cl2, in a new mineral found in sublimates of the Yadovitaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. The sublimates were collected in an open cave about 1.5 m wide and 2 m deep with an interior temperature of up to 340 °C with walls thickly encrusted by a diverse assemblage of minerals (dominantly sulfates). Yaroshevskite occurs very rarely on crusts that mainly consist of bright green euchlorine in association with fedotovite, hematite, tenorite, Cu-rich lyonsite, melanothallite, atlasovite, kamchatkite and secondary supergene avdoninite, belloite, and chalcanthite. Yaroshevskite forms isolated prismatic crystals up to 0.1 × 0.15 × 0.3 mm. Crystals are black and opaque, have a reddish black streak, metallic to adamantine luster, are brittle, show no cleavage and an uneven fracture. The micro-indentation measurements VHN = 172 (165–179) kg/mm2 corresponding to a Mohs hardness of ~3½. The density could not be measured due to the paucity of the material; Dcalc = 4.86 g/cm3. Yaroshevskite is gray with a weak bluish hue in reflected light, shows no internal reflections or bireflectance and a very weak anisotropy. The reflectance values (measured between 400 and 700 nm in 20 nm intervals) are [R % (λ nm)]: 15.8 (400), 16.2 (420), 16.3 (440), 16.2 (460), 16.0 (480), 15.8 (500), 15.5 (520), 15.3 (540), 15.2 (560), 14.9 (580), 14.7 (600), 14.5 (620), 14.4 (640), 14.2 (660), 14.0 (680), 13.8 (700). The average of 5 electron probe WDS analyses is [wt% (range)]: CuO 61.82 (60.8–62.4), ZnO 0.53 (0.4–0.8), Fe2O3 0.04 (0.00–0.07), V2O5 31.07 (30.5–31.7), As2O5 0.32 (0.2–0.4), MoO3 1.56 (1.0–1.9), Cl 6.23 (6.0–6.6), O=Cl2 –1.41, total 100.16. The empirical formula based on 20 (O+Cl) anions pfu is (Cu8.80Zn0.07Fe0.01)∑8.88(V3.87Mo0.12As0.03)∑4.02O18.01Cl1.99. The strongest lines in the X-ray powder-diffraction pattern [dobs (Å) (Iobs%; hkl)] are: 8.65 (100; 001), 6.84 (83; 01̄1), 6.01 (75; 100), 5.52 (60; 1̄01), 4.965 (55; 011), 4.198 (67; 1̄1̄1), 4.055 (65; 110), 3.120 (55; 021), 2.896 (60; 21̄1,003,2̄20). The unit-cell parameters refined from powder-diffraction data are: a = 6.4528(3), b = 8.3121(5), c = 9.1700(4) Å, α = 105.208(5), β = 96.147(5), γ = 107.881(5)°, V = 442.16 Å3, and Z = 1. Single-crystal X-ray diffraction data collected on a crystal of size 0.03 × 0.09 × 0.23 mm refined to R1 = 0.0737 for 2026 unique reflections with I ≥ 2σ(I) shows yaroshevskite is triclinic, space group P1̄, with a = 6.4344(11), b = 8.3232(13), c = 9.1726(16) Å, α = 105.338(14), β = 96.113(14), γ = 107.642(1)°, V = 442.05 Å3, and Z = 1. The crystal structure of yaroshevskite is based on corrugated layers coplanar with ac. The layers are made up of chains of edge-sharing flat squares with central Cu2+ cations, with neighboring chains connected via groups of three Cu2+-centered squares. The neighboring layers are connected via pairs of CuO4Cl fivefold-coordinated polyhedra and isolated VO4 tetrahedra. The name is in honor of the Russian geochemist Alexei Andreevich Yaroshevsky (b. 1934), professor in the Department of Geochemistry at the Faculty of Geology of Moscow State University. The type specimen of yaroshevskite has been deposited in the collection of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia. O.C.G.

*
All minerals marked with an asterisk have been approved by the IMA CNMMC.
For a complete listing of all IMA-validated unnamed minerals and their codes, see http://pubsites.uws.edu.au/ima-cnmnc/.