Search

The effort for determining NMR interaction tensors from orientation-dependent spectra of single crystals may be greatly reduced by exploiting symmetry relations between atoms of the observed nuclide in the unit cell, as is well documented in the literature. In this work, we determined both the full chemical shift (CS) tensor of 207Pb and the unknown orientation of the rotation axis for the natural mineral phosgenite, Pb2Cl2CO3, from a single rotation pattern, i.e. spectra of crystal orientations from 0 to 180°. In the tetragonal crystal structure of phosgenite, four symmetry-related, but magnetically inequivalent 207Pb are generated by the Wyckoff multiplicity. The mineral wulfenite, PbMoO4, also crystallises in a tetragonal space group, but the site multiplicity for 207Pb generates only one magnetically inequivalent atom, thus not supplying sufficient experimental data to determine CS tensor and axis orientation from an arbitrary number of rotation patterns. One solution to this problem is to simultaneously acquire data of a known compound with high symmetry and Wyckoff multiplicity (here: phosgenite), which supplies additional constraints making the solution of the target compound (here: wulfenite) possible. The 207Pb CS tensors thus determined are characterised by the following eigenvalues in ppm: δ 11 P A S = ( − 2553 ± 1 ) , δ 22 P A S = ( − 1929 ± 1 ) , δ 33 P A S = ( − 1301 ± 1 ) for phosgenite, and δ 11 P A S = ( − 2074 ± 1 ) , δ 22 P A S = ( − 2074 ± 1 ) , δ 33 P A S = ( − 1898 ± 1 ) for wulfenite.

Davidbrownite-(NH4), (NH4,K)5(V4+O)2(C2O4)[PO2.75(OH)1.25]4·3H2O, is a new mineral species from the Rowley mine, Maricopa County, Arizona, USA. It occurs in an unusual bat-guano-related, post-mining assemblage of phases that include a variety of vanadates, phosphates, oxalates and chlorides, some containing NH4+. Other secondary minerals found in association with davidbrownite-(NH4) are antipinite, fluorite, mimetite, mottramite, quartz, rowleyite, salammoniac, struvite, vanadinite, willemite and wulfenite. Crystals of davidbrownite-(NH4) are light green–blue needles or narrow blades up to ~0.2 mm long. The streak is white, the lustre is vitreous, Mohs hardness isca. 2, tenacity is brittle and fracture is splintery. There are two good cleavages in the [010] zone, probably {100} and {001}. The measured density is 2.12(2) g cm–3. Davidbrownite-(NH4) is optically biaxial (+) with α = 1.540(2), β = 1.550(5) and γ = 1.582(2) (white light); 2V = 58.5(5)°; moderater>vdispersion; and orientationZ=bandY≈a. Pleochroism:X= pale blue,Y= nearly colourless,Z= light blue; andY 2σIreflections) consists of a chain structural unit with the formula {(V4+O)2(C2O4)[PO2.75(OH)1.25]4}5–, and a disordered interstitial complex containing five large monovalent cations (NH4+and K+) and three H2O groups pfu. Strong hydrogen bonds form links within and between the chains.

Wulfenite, PbMoO4, is a common secondary mineral found in oxidiation zones of many hydrothermal lead deposits. The molybdenum that occupies the tetrahedral site, surrounded by four oxygen atoms, st...

Natural wulfenite is lead molybdate (PbMoO4), which has extensive and vital economical values based on its rarity and molybdenum extraction. Through the density functional theory calculation, the electronic structure and bond population were first investigated, and the predominantly exposed surfaces were predicted. Based on the calculations, the {1 1 2} and {0 0 1} surfaces are expected to be the most common cleavage surfaces due to their lower surface energies, smaller broken bond densities, and larger interlayer spacings than other surfaces; and the results are consistent with the X-ray diffraction (XRD) observations. Moreover, the {1 1 2} and {0 0 1} cleavage surfaces were intuitively observed by atomic force microscopy (AFM), and {1 1 2} cleavage surfaces are rather smooth and flat, while the {0 0 1} cleavage surface have separated terrace, indicating that the cleavages occur more easily along {1 1 2} surfaces than along {0 0 1} surfaces. The above conclusions in this paper have important theoretical significance and guidance on in-deep understanding of the wulfenite leaching and flotation mechanisms.

The new mineral species suseinargiuite, (Na 0.5 Bi 0.5 )MoO 4 , has been discovered in the Mo-Bi occurrence of Su Seinargiu, Sarroch, Cagliari, Sardinia, Italy. It occurs as hemispherical aggregates of very small acicular crystals, up to some micrometres in length. It is colourless, with a pearly to adamantine lustre. In the studied specimens, suseinargiuite is associated with wulfenite. Micro-Raman spectra were collected in the region between 100 and 2000 cm −1 . The following bands have been observed (in cm −1 ): 131, 188, 319, ~ 376, ~ 772, and 876. Electron microprobe data collected on a chemically zoned grain gave (outer and inner zone, respectively – in wt%): MoO 3 49.03, Bi 2 O 3 42.97, PbO 2.89, Na 2 O 3.69, total 98.58, and MoO 3 45.59, Bi 2 O 3 34.47, PbO 12.04, Na 2 O 3.03, total 95.13. On the basis of 4 O atoms per formula unit, the chemical formulae are (Na 0.35 Bi 0.54 Pb 0.04 ) Σ=0.93 Mo 0.99 O 4 and (Na 0.31 Bi 0.46 Pb 0.17 ) Σ=0.94 Mo 0.99 O 4 , respectively. Main diffraction lines are [ d in A (relative intensity) hkl ]: 3.146 (100) 112, 2.912 (13) 004, 2.652 (18) 200, 1.964 (34) 204, 1.875 (15) 220, 1.728 (19) 116, and 1.616 (28) 312 and 132. Unit-cell parameters, refined from the powder X-ray diffraction data in a tetragonal setting, space group I 4 1 / a , are a = 5.296(1), c = 11.673(2) A, V = 327.4(1) A 3 , Z = 4. Owing to the lack of suitable crystals and the very small amount of available material, the crystal structure of suseinargiuite was not solved. However, X-ray powder diffraction data, micro-Raman spectra, as well as chemical analysis, show the close correspondence between suseinargiuite with synthetic (Na 0.5 Bi 0.5 )MoO 4 , which displays a scheelite-type structure.

Bluebellite, Cu6[I5+O3(OH)3](OH)7Cl and mojaveite, Cu6[Te6+O4(OH)2](OH)7Cl, are new secondary copper minerals from the Mojave Desert. The type locality for bluebellite is the D shaft, Blue Bell claims, near Baker, San Bernardino County, California, while cotype localities for mojaveite are the E pit at Blue Bell claims and also the Bird Nest drift, Otto Mountain, also near Baker. The two minerals are very similar in their properties. Bluebellite is associated particularly with murdochite, but also with calcite, fluorite, hemimorphite and rarely dioptase in a highly siliceous hornfels. It forms bright bluishgreen plates or flakes up to ~20 mm 620 mm 65 mm in size that are usually curved. The streak is pale bluish green and the lustre is adamantine, but often appears dull because of surface roughness. It is non-fluorescent. Bluebellite is very soft (Mohs hardness ~1), sectile, has perfect cleavage on {001} and an irregular fracture. The calculated density based on the empirical formula is 4.746 g cm–3. Bluebellite is uniaxial (–), with mean refractive index estimated as 1.96 from the Gladstone-Dale relationship. It is pleochroic O (bluish green) >> E (nearly colourless). Electron microprobe analyses gave the empirical formula Cu5.82I0.99Al0.02Si0.12O3.11(OH)9.80Cl1.09 based on 14 (O+Cl) a.p.f.u. The Raman spectrum shows strong iodate-related bands at 680, 611 and 254 cm–1. Bluebellite is trigonal, space group R3, with the unit-cell parameters: a = 8.3017(5), c = 13.259(1) Å , V = 791.4(1) Å 3 and Z = 3. The eight strongest lines in the powder X-ray diffraction (XRD) pattern are [dobs/Å (I) (hkl)]: 4.427(99)(003), 2.664(35)(211), 2.516(100)(21), 2.213(9)(006), 2.103(29)(033,214), 1.899(47)(312,21), 1.566(48)(140,217) and 1.479(29)(045,14,324).Mojaveite occurs at the Blue Bell claims in direct association with cerussite, chlorargyrite, chrysocolla, hemimorphite, kettnerite, perite, quartz and wulfenite, while at the Bird Nest drift, it is associated with andradite, chrysocolla, cerussite, burckhardtite, galena, goethite, khinite, mcalpineite, thorneite, timroseite, paratimroseite, quartz and wulfenite. It has also been found at the Aga mine, Otto Mountain, with cerussite, chrysocolla, khinite, perite and quartz. Mojaveite occurs as irregular aggregates of greenish-blue plates flattened on {001} and often curved, which rarely show a hexagonal outline, and also occurs as compact balls, from sky blue to medium greenish blue in colour. Aggregates and balls are up to 0.5 mm in size. The streak of mojaveite is pale greenish blue, while the lustre may be adamantine, pearly or dull, and it is non-fluorescent. The Mohs hardness is ~1. It is sectile, with perfect cleavage on {001} and an irregular fracture. The calculated density is 4.886 g cm–3, based on the empirical formulae and unit-cell dimensions. Mojaveite is uniaxial (–), with mean refractive index estimated as 1.95 from the Gladstone-Dale relationship. It is pleochroic O (greenish blue) >> E (light greenish blue). The empirical formula for mojaveite, based on 14 (O+Cl) a.p.f.u., is Cu5.92Te1.00Pb0.08Bi0.01O4(OH)8.94Cl1.06. The most intense Raman bands occur at 694, 654 (poorly resolved), 624, 611 and 254 cm–1. Mojaveite is trigonal, space group R3, with the unit-cell parameters: a = 8.316(2), c = 13.202(6) Å and V = 790.7(1) Å 3. The eight strongest lines in the powder XRD pattern are [dobs/Å (I) (hkl)]: 4.403(91)(003), 2.672(28)(211), 2.512(100)(21), 2.110(27)(033,214), 1.889(34)(312,21,22), 1.570(39)(404,140,217), 1.481(34)(045,14,324) and 1.338(14)(422). Diffraction data could not be refined, but stoichiometries and unit-cell parameters imply that bluebellite and mojaveite are very similar in crystal structure. Structure models that satisfy bondvalence requirements are presented that are based on stackings of brucite-like Cu6MX14 layers, where M = (I or Te) and X = (O, OH and Cl). Bluebellite and mojaveite provide a rare instance of isotypy between an iodate containing I5+ with a stereoactive lone electron pair and a tellurate containing Te6+ with no lone pair.

Rowleyite, [ Na ( NH 4 , K ) 9 Cl 4 ] [ V 2 5 + , 4 + ( P , As ) O 8 ] 6 · n [ H 2 O , Na , NH 4 , K , Cl ] , is a new mineral species from the Rowley mine, Maricopa County, Arizona, U.S.A. It was found in an unusual low-temperature, apparently post-mining suite of phases that include various vanadates, phosphates, oxalates, and chlorides, some containing NH 4 + . Other secondary minerals found in association with rowleyite are antipinite, fluorite, mimetite, mottramite, quartz, salammoniac, struvite, vanadinite, willemite, wulfenite, and several other potentially new minerals. Analyzed δ 13 C values for the antipinite in association with rowleyite are consistent with a bat guano source. Crystals of rowleyite are very dark brownish green (appearing black) truncated octahedra up to about 50 μm in diameter. The streak is brownish green, the luster is vitreous, very thin fragments are transparent. The Mohs hardness is about 2, the tenacity is brittle, fracture is irregular, there is no cleavage, and the measured density is 2.23(2) g/cm 3 . Rowleyite is optically isotropic with n = 1.715(5). Electron microprobe analyses yielded the empirical formula [ ( NH 4 ) 8 . 81 Na 3 . 54 K 2 . 58 ) Σ 14 . 93 Cl 6 . 29 ( H 2 O ) 16 ] [ ( V 9 . 36 5 + V 2 . 64 4 + ) Σ 12 ( P 5 . 28 As 0 . 72 5 + ) Σ 6 O 48 ] . Raman and infrared spectroscopy confirmed the presence of NH 4 and H 2 O. Rowleyite is cubic, F d 3 ¯ m , with a = 31.704(14) A, V = 31867(42) A 3 , and Z = 16. The crystal structure of rowleyite ( R 1 = 0.040 for 1218 F o > 4σ F reflections) contains [V 4 O 16 ] 12+ polyoxovanadate units that link to one another via shared vertices with [(P,As)O 4 ] 3− tetrahedra to form a 3D framework possessing large interconnected channels. The channels contain a 3D ordered [Na(NH 4 ,K) 9 Cl 4 ] 6+ salt net, which apparently served as a template for the formation of the framework. In that respect, rowleyite can be considered a salt-inclusion solid (SIS). The rowleyite framework is among the most porous known.

Bobmeyerite, Pb4(Al3Cu)(Si4 O12)(S0.5Si0.5O4)(OH)7 Cl(H2O)3, is a new mineral from the Mammoth - Saint Anthony mine, Tiger, Pinal County, Arizona, USA. It occurs in an oxidation zone assemblage attributed to progressive alteration and crystallization in a closed system. Other minerals in this assemblage include atacamite, caledonite, cerussite, connellite, diaboleite, fluorite, georgerobinsonite, hematite, leadhillite, matlockite, murdochite, phosgenite, pinalite, quartz, wulfenite and yedlinite. Bobmeyerite occurs as colourless to white or cream-coloured needles, up to 300 m m in length, that taper to sharp points. The streak is white and the lustre is adamantine, dull or silky. Bobmeyerite is not fluorescent. The hardness could not be determined, the tenacity is brittle and no cleavage was observed. The calculated density is 4.381 g cm-3. Bobmeyerite is biaxial (-) with α ≈ β = 1.759(2), γ = 1.756(2) (white light), it is not pleochroic; the orientation is X = c; Y or Z = a or b. Electron-microprobe analyses provided the empirical formula Pb3.80Ca0.04Al3.04Cu2+0.96Cr3+0.13Si4.40S0.58O24.43Cl1.05F0.52H11.83. Bobmeyerite is orthorhombic (pseudotetragonal), Pnnm with unit-cell parameters a = 13.969(9), b = 14.243(10), c = 5.893(4) Å, V = 1172.5(1.4) Å3 and Z = 2. The nine strongest lines in the X-ray powder diffraction pattern, listed as [dobs (Å)(I)(hkl)], are as follows: 10.051(35)(110); 5.474(54)(011,101); 5.011(35)(220); 4.333(43)(121,211); 3.545(34)(040,400); 3.278(77)(330,231,321); 2.9656(88)(141,002,411); 2.5485(93)(051,222,501); 1.873(39)(multiple). Bobmeyerite has the same structural framework as cerchiaraite and ashburtonite. In the structure, which refined to R1 = 0.079 for 1057 reflections with F > 4σF, SiO4 tetrahedra share corners to form four-membered Si4O12 rings centred on the c axis. The rings are linked by chains of edge-sharing AlO6 octahedra running parallel to [001]. The framework thereby created contains large channels, running parallel to [001]. The Cl site is centred on the c axis alternating along [001] with the Si4O12 rings. Two non-equivalent Pb atoms are positioned around the periphery of the channels. Both are elevencoordinate, bonding to the Cl atom on the c axis, to eight O atoms in the framework and to two O (H2O) sites in the channel. The Pb atoms are off-centre in these coordinations, as is typical of Pb2+ with stereo-active lone-electron pairs. A (S, Si, Cr)O4 group is presumed to be disordered in the channel. The name honours Robert (Bob) Owen Meyer, one of the discoverers of the new mineral.

Fuettererite, Pb_3Cu^6^(2+)Te^(6+)O_6(OH)_7Cl_5, is a new tellurate from Otto Mountain near Baker, California, named for Otto Fuetterer who is largely responsible for the development of the mining claims on Otto Mountain. The new mineral is known from only two specimens, one from the NE2 vein and the other from the Bird Nest drift. Fuettererite occurs in vugs in quartz, on the first specimen associated with Br-rich chlorargyrite, iodargyrite, and telluroperite and on the second specimen associated with angle-site, anatacamite, atacamite, chalcopyrite, galena, goethite, hematite, muscovite, phosphohedyphane, timroseite, and wulfenite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Fuettererite is hexagonal, with space group R3, a = 8.4035(12), c = 44.681(4) A, V = 2732.6(6) A3, and Z = 6. Crystals are tabular to short prismatic, exhibit the forms {100}, {101}, and {001} and reach a maximum dimension of 50 μm. The color is bluish green, the streak is pale bluish-green, and the luster is adamantine. The Mohs hardness is estimated at between 2 and 3. The new mineral is brittle with irregular fracture and one perfect cleavage on {001}. The calculated density based on the empirical formula is 5.528 g/cm^3. Fuettererite is uniaxial (−), with calculated indices of refraction of ω = 2.04 and ɛ = 1.97, and is dichroic bluish-green, E 4σF) contains edge-sharing sheets of CuO_5Cl and TeO_6 octahedra. These sheets are virtually identical to that in the structure of spangolite, but in fuettererite they are linked together to form a double sheet. The double octahedral sheets alternate with thick double layers of PbO_2Cl_6 polyhedra. The CuO_5Cl octahedra exhibit pronounced Jahn-Teller distortions and the PbO_2Cl_6 polyhedron has a lopsided distribution of bond lengths attributable to the localization of the Pb^(2+) 6s^2 lone-pair electrons.

Agaite, Pb_3Cu^(2+)Te^(6+)O_5(OH)_2(CO_3), is a new tellurate from the Aga mine on Otto Mountain near Baker, California, U.S.A. The new mineral is known from only one specimen. It occurs on quartz in association with cerussite, Br-rich chlorargyrite, chrysocolla, goethite, khinite, markcooperite, muscovite, phosphohedyphane, timroseite, and wulfenite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Agaite is orthorhombic, space group Pcɑ2_1, with unit-cell dimensions ɑ = 10.6522(7), b = 9.1630(5), c = 9.6011(7) A, V = 937.12(11) A^3, and Z = 4. Agaite crystals form as blades flattened on {010} and probably elongated on [001], and are up to about 20 μm thick and 200 μm in length. The color is blue, the streak is pale blue, and the luster is adamantine. The Mohs hardness is estimated at between 2 and 3. Agaite is brittle with an irregular fracture and one perfect cleavage on {010}. The calculated density based on the empirical formula is 6.987 g/cm^3. Agaite is biaxial (−), with calculated indices of refraction of α = 2.015, β = 2.065, and γ = 2.070°. The measured 2V is 34(5)° and the optical orientation is X = b, Y =c, and Z = a. It is pleochroic: X = pale blue, Y and Z = blue; X 4 σF) contains edge-sharing chains of Cu^(2+)O_5 square pyramids and Te^(6+)O_6 octahedra parallel to a that are joined by corner-sharing in the c direction, forming a polyhedral sheet parallel to {010}. The polyhedral sheet is very similar to those in the structures of timroseite and paratimroseite. The thick interlayer region contains 8- and 9-coordinated Pb^(2+), as well as CO_3 and OH groups. The Pb coordinations have lopsided distributions of bond lengths attributable to the localization of the Pb^(2+) 6s^2 lone-pair electrons.

Chromschieffelinite, Pb-(10)Te_6O_(20)(OH)_(14)(CrO_4)(H_2O)_5, is a new tellurate from Otto Mountain near Baker, California, named as the chromate analog of schieffelinite, Pb_(10)Te_6O_(20)(OH)_(14)(SO_4)(H_2O)_5. The new mineral occurs in a single 1 mm vug in a quartz vein. Associated mineral species include: chalcopyrite, chrysocolla, galena, goethite, hematite, khinite, pyrite, and wulfenite. Chromschieffelinite is orthorhombic, space group C222_1, a = 9.6646(3), b = 19.4962(8), c = 10.5101(7) A, V = 1980.33(17) A3, and Z = 2. Crystals are blocky to tabular on {010} with striations parallel to [001]. The forms observed are {010}, {210}, {120}, {150}, {180}, {212}, and {101}, and crystals reach 0.2 mm in maximum dimension. The color and streak are pale yellow and the luster is adamantine. The Mohs hardness is estimated at 2. The new mineral is brittle with irregular fracture and one perfect cleavage on {010}. The calculated density based on the ideal formula is 5.892 g/cm^3. Chromschieffelinite is biaxial (−) with indices of refraction α = 1.930(5), β = 1.960(5), and γ = 1.975(5), measured in white light. The measured 2V is 68(2)°, the dispersion is strong, r < v, and the optical orientation is X = b, Y = c, Z = a. No pleochroism was observed. Electron microprobe analysis provided: PbO 59.42, TeO_3 29.08, CrO_3 1.86, H_2O 6.63 (structure), total 96.99 wt%; the empirical formula (based on 6 Te) is Pb_(9.65)Te_6O_(19.96)(OH)_(14.04)(CrO_4)_(0.67)(H_2O)_(6.32). The strongest powder X-ray diffraction lines are [d_(obs) in A (hkl) I]: 9.814 (020) 100, 3.575 (042,202) 41, 3.347 (222) 44, 3.262 (241,060,113) 53, 3.052 (311) 45, 2.9455 (152,133) 55, 2.0396 (115,353) 33, and 1.6500 (multiple) 33. The crystal structures of schieffelinite (R_1 = 0.0282) and chromschieffelinite (R_1 = 0.0277) contain isolated Te^(6+)O_6 octahedra and Te_2^(6+)O_(11) corner-sharing dimers, which are linked into a three-dimensional framework via bonds to Pb2+ atoms. The framework has large channels along c, which contain disordered SO_4 or CrO_4 groups and H_2O. The lone-electron pair of each Pb^(2+) is stereochemically active, resulting in one-sided Pb-O coordination arrangements. The short Pb-O bonds of the Pb^(2+) coordinations are all to Te^(6+)O_6 octahedra, resulting in strongly bonded layers parallel to {010}, which accounts for the perfect {010} cleavage.

A new mineral species, markascherite (IMA2010-051), ideally Cu3(MoO4)(OH)4, has been found at Copper Creek, Pinal County, Arizona, U.S.A. The mineral is of secondary origin and is associated with brochantite, antlerite, lindgrenite, wulfenite, natrojarosite, and chalcanthite. Markascherite crystals are bladed (elongated along the b axis), up to 0.50 × 0.10 × 0.05 mm. The dominant forms are {001}, {100}, and {010}. Twinning is found with the twofold twin axis along [101]. The mineral is green, transparent with green streak and vitreous luster. It is brittle and has a Mohs hardness of 3.5~4; cleavage is perfect on {100} and no parting was observed. The calculated density is 4.216 g/cm 3 . Optically, markascherite is biaxial (–), with nα >1.8, nβ > 1.8, and nγ >1.8. The dispersion is strong (r > v). It is insoluble in water, acetone, or hydrochloric acid. An electron microprobe analysis yielded an empirical formula Cu2.89(Mo1.04O4)(OH)4. Markascherite, polymorphic with szenicsite, is monoclinic, with space group P21/m and unit-cell parameters a = 9.9904(6), b = 5.9934(4), c = 5.5255(4) A, β = 97.428(4)°, and V = 328.04(4) A 3 . Its structure is composed of three nonequivalent, markedly distorted Cu 2+ (O,OH)6 octahedra and one MoO4 tetrahedron. The Cu1 and Cu2 octahedra share edges to form brucite-type layers parallel to (100), whereas the Cu3 octahedra share edges with one another to form rutile-type chains parallel to the b axis. These layers and chains alternate along [100] and are interlinked together by both MoO4 tetrahedra and hydrogen bonds. Topologically, the structure of markascherite exhibits a remarkable resemblance to that of deloryite, Cu4(UO2)(MoO4)2(OH)6, given the coupled substitution of [2Cu 2+ + 2(OH

Georgerobinsonite, Pb 4 (CrO 4 ) 2 (OH) 2 FCl, is a new chromate mineral species from the Mammoth – St. Anthony mine, Tiger, Pinal County, Arizona. It occurs as minute intergrowths of thin tabular orange crystals less than 0.1 mm across with {001} dominant and minor {010} and {110}, associated with caledonite, a cerchiaraite-related mineral, cerussite, diaboleite, Cr-bearing leadhillite, matlockite, murdochite, pinalite, wulfenite and yedlinite, in vugs in a silicified matrix. Georgerobinsonite is orange-red, transparent and has a pale orange streak and an adamantine luster, and it does not fluoresce under ultraviolet light. No cleavage or parting was observed. The Mohs hardness is 2½–3; georgerobinsonite is brittle with an uneven fracture. The calculated density is 6.23 g/cm 3 . The indices of refraction are α ≈ 2.07, β > 2.11, γ > 2.11; 2 V (obs) = 84(2)°; it is strongly pleochroic, α orange, γ yellow; optical orientation: X = a , Y = c and Z = b , and the dispersion is strong with r > v . Georgerobinsonite is orthorhombic, space group Pmmn , a 7.613(2), b 11.574(3), c 6.883(2) A, V 606.5(3) A 3 , Z = 2, a:b:c = 0.6578:1:0.5947. The strongest six lines in the X-ray powder-diffraction pattern [ d in A( I )( hkl )] are: 2.131(100)(232), 3.308(80)(012), 3.195(80)(211, 220), 6.371(60) (110), 3.357(60)(031, 201) and 3.143(60)(102). Chemical analysis with an electron microprobe gave CrO 3 14.79, PbO 77.99, SO 3 1.64, F 1.47, Cl 3.39, H 2 O (calc.) 1.52, sum 99.42 wt.%; the valence states of Pb, Cr and S, and the amount of H 2 O, were determined by crystal-structure analysis. The resulting empirical formula, on the basis of 12 (O, F, Cl, OH) anions, is Pb 4.09 (Cr 6+ 1.73 S 6+ 0.24 ) ∑1.97 O 8 (OH) 1.98 F 0.90 Cl 1.12 . The crystal structure of georgerobinsonite was solved by direct methods and refined to an R 1 index of 2.0% based on 574 observed reflections collected on a four-circle diffractometer with Mo K α X-radiation. There are two Pb 2+ cations coordinated by eight and nine anions, and both show prominent lone-pair stereoactive behavior. The Pb polyhedra share faces and edges to form layers parallel to {001} that are linked into a heteropolyhedral framework by (CrO 4 ) groups, with hydrogen bonding between OH and Cl anions. The mineral is named after Dr. George Willard Robinson (b. 1946), mineral curator, researcher, teacher and field collector.

The new mineral fluorphosphohedyphane, Ca_2Pb_3(PO_4)_3F, the F-analog of phosphohedyphane, is hexagonal with space group P6_3/m and cell parameters a = 9.6402(12), c = 7.0121(8) A, V = 564.4(1) A^3, and Z = 2. It occurs in the oxidation zone of a small Pb-Cu-Zn-Ag deposit, the Blue Bell claims, about 11 km west of Baker, San Bernardino County, California. It forms as sub-parallel intergrowths and irregular clusters of transparent, colorless, highly lustrous, hexagonal prisms with pyramidal terminations. It is found in cracks and narrow veins in a highly siliceous hornfels in association with cerussite, chrysocolla, fluorite, fluorapatite, goethite, gypsum, mimetite, opal, phosphohedyphane, plumbogummite, plumbophyllite, plumbotsumite, pyromorphite, quartz, and wulfenite. The streak of the new mineral is white, the luster is subadamantine, and the Mohs hardness is about 4. The mineral is brittle with subconcoidal fracture and no cleavage. The calculated density is 5.445 g/cm^3 based upon the empirical formula. Optical properties (589 nm): uniaxial (–),ω= 1.836(5), e= 1.824(5), nonpleochroic. SEM-EDS analyses yielded the averages and ranges in wt%: O 21.28 (20.31–22.14), F 1.59 (1.38–1.91), P 10.33 (9.81–10.83), Ca 9.66 (8.97–10.67), Pb 60.08 (57.67–61.21), total 102.95 (102.02–103.88), providing the empirical formula (based on P = 3): Ca2.00(Pb_(2.61)Ca_(0.17)) Σ_(2.78)P_3O_(11.91)F_(0.75). Infrared spectroscopy showed no evidence of OH or carbonate. The strongest powder X-ray diffraction lines are [d(hkl)I]: 8.38(100)22, 3.974(111)28, 3.506(002)25, 2.877(121,211)100, 1.878(213,123)26. Fluorphosphohedyphane has the apatite structure (R_1 = 1.75% for 444 reflections with F_o > 4 F) with ordering of Ca and Pb in two cation sites, as in hedyphane and phosphohedyphane. The Pb^(2+) cation exhibits a stereoactive 6s^2 lone-electron-pair. The X anion site at (0, 0,1/2) is fully occupied by F forming six bonds of 2.867 A to Pb atoms, in contrast to the six Pb-Cl bonds of 3.068 A in phosphohedyphane.

Markcooperite, Pb_2(UO_2)Te^(6+)O_6, is a new tellurate from Otto Mountain near Baker, California, named in honor of Mark A. Cooper of the University of Manitoba for his contributions to mineralogy. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins. Markcooperite is directly associated with bromian chlorargyrite, iodargyrite, khinite-4O, wulfenite, and four other new tellurates: housleyite, thorneite, ottoite, and timroseite. Various other secondary minerals occur in the veins, including two other new secondary tellurium minerals: paratimroseite and telluroperite. Markcooperite is monoclinic, space group P2_1/c, a = 5.722(2), b = 7.7478(2), c = 7.889(2) Å, β = 90.833(5)°, V = 349.7(2) Å^3, and Z = 2. It occurs as pseudotetragonal prisms to 0.2 mm with the forms {100} and {011} and as botryoidal intergrowths to 0.3 mm in diameter; no twinning was observed. Markcooperite is orange and transparent, with a light orange streak and adamantine luster, and is non-fluorescent. Mohs hardness is estimated at 3. The mineral is brittle, with an irregular fracture and perfect {100} cleavage. The calculated density is 8.496 g/cm3 based on the empirical formula. Markcooperite is biaxial (+), with indices of refraction α= 2.11, β = 2.12, γ= 2.29 calculated using the Gladstone-Dale relationship, measured α-β birefringence of 0.01 and measured 2V of 30(5)°. The optical orientation is X = c, Y = b, Z = a. The mineral is slightly pleochroic in shades of orange, with absorption: X > Y = Z. No dispersion was observed. Electron microprobe analysis provided PbO 50.07, TeO_3 22.64, UO_3 25.01, Cl 0.03, O≡Cl –0.01, total 97.74 wt%; the empirical formula (based on O+Cl = 8) is Pb_(2.05)U_(0.80)Te^(6+)_(1.18)O_(7.99)Cl_(0.01). The strongest powder X-ray diffraction lines are [d_(obs) in Å (hkl) I]: 3.235 (120, 102, 1[overbar]02) 100, 2.873 (200) 40, 2.985 (1[overbar]21, 112, 121) 37, 2.774 (022) 30, 3.501 (021, 012) 29, 2.220 (221, 2[overbar]21, 212) 23, 1.990 (222, 2[overbar]22) 21, and 1.715 (320) 22. The crystal structure (R_1 = 0.052) is based on sheets of corner-sharing uranyl square bipyramids and tellurate octahedra, with Pb atoms between the sheets. Markcooperite is the first compound to show Te^(6+) substitution for U^(6+) within the same crystallographic site. Markcooperite is structurally related to synthetic Pb(UO_2)O_2.

Three natural crystals of the wulfenite (PbMoO4)—stolzite (PbWO4) series were investigated by single-crystal X-ray diffraction. The results indicate that the symmetry is I41/a from nearly pure wulfenite to intermediate compositions, in contrast to previous work which claimed a symmetry change to 74 symmetry (acentric) for intermediate compositions compared with I41/a (centric space group) for the end-members. The results reported here show that the reflections violating I41/a symmetry observed in this work and in a previous study are related primarily to λ/2 effects, even if Renninger effects are not excluded. Consequently, we find that the I41/a symmetry is retained throughout the wulfenite— stolzite.

Mambertiite, BiMo5+ 2.80O8(OH), is a new mineral identified in small vugs of quartz veins from Su Seinargiu, Sarroch, Cagliari, Sardinia, Italy. It occurs as pale yellow {001} tabular crystals, up to 1 mm in length and few mm thick, with adamantine lustre. Mambertiite is brittle, with a conchoidal fracture. It is associated with ferrimolybdite, muscovite, quartz, sardignaite, and wulfenite. Electron microprobe data (wt% – mean of 12 spot analyses) are: Mo2O5 59.59, Bi2O3 36.96, WO3 2.03, H2Ocalc 1.48, sum 100.06. On the basis of 9 O atoms per formula unit, the empirical formula is Bi0.99(Mo5+2.74W0.05)Σ2.79O7.97(OH)1.03. Infrared spectra showed absorption bands consistent with the occurrence of OH− groups. Mambertiite is triclinic, space group ![Formula][1] , with a = 5.854(2), b = 9.050(3), c = 7.637(3) A, α = 112.85(1), β = 102.58(1), γ = 90.04(1)°, V = 362.3(2) A3, Z = 2. The crystal structure of mambertiite was solved and refined down to R 1 = 0.050 on the basis of 2019 observed [ F o > 4σ( F o)] reflections. It is composed by eight-fold coordinated Bi-centred polyhedra and five independent Mo-centred octahedra. Among the latter, two are completely occupied by molybdenum, whereas the remaining three are only partially occupied. Two kinds of ( ![Formula][2] ) layers occur in mambertiite, alternating along [ ![Formula][3] ]*: one is composed by Bi-centered polyhedra and the two partially occupied Mo4 and Mo5 sites, whereas the other is composed by the zigzag chains, running along c , formed by the fully occupied Mo1 and Mo2 sites, and the partially occupied Mo3 site. Mambertiite is structurally related to gelosaite, BiMo6+2O7(OH) · H2O; their relationships can be conveniently described through the OD theory. Mambertiite is the fourth known mineral with Bi and Mo as essential components. Its name honours the Italian mineral collector Marzio Mamberti (b. 1959) for his contribution to the knowledge of the Sardinian mineralogy. The mineral and its name have been approved by the IMA CNMNC (No. 2013–098). [1]: /embed/mml-math-1.gif [2]: /embed/mml-math-2.gif [3]: /embed/mml-math-3.gif

The single-crystal X-ray structure of tungstenian wulfenite-I41/a containing 10 mol.% WO3 from the San Francisco mine, Sonora, Mexico, space group I41/a, a = 5.436(2), c = 12.068(8)Å and Z = 4, has been refined to R = 0.052. The Mo and W are disordered over special position 4a (0,0,0) in the lattice. Tungstenian wulfenite-I4̄ (‘chillagite’) from the Christmas Gift mine, Chillagoe, Queensland, Australia (Museum of Victoria specimen M16934), crystallizes in the closely related tetragonal space group I4̄, with a = 5.441(1), c = 12.068(6) Å and Z = 4. The structure was refined to R = 0.038. Refined site occupancy factors show that Mo and W are not distributed equally over the two crystallographically independent Mo/W positions, being 0.136(2) for Mo and 0.114(2) for W in special position 2a (0,0,0) and 0.184(2) for Mo and 0.066(2) for W in special position 2c (0,Ý,Ü). These give a composition corresponding to wulfenite64stolzite36, in agreement with analytical data. The Mo/W distributions in the unit cell provide one explanation for the origin of hemihedrism in the wulfenite-stolzite series.

Bamfordite from the abandoned W-Mo-Bi mines at Bamford, Queensland, Australia, is a new hydrated iron molybdate with a unique structure. This mineral formed by oxidation of molybdenite, MoS 2 . in the presence of strongly acidic solutions. It occurs as microcrystalline aggregates of tabular triclinic crystals between 0.005 and 0.05 mm long. The aggregates are apple-green with an earthy luster and greenish yellow streak. Crystals are transparent, with pale to moderate yellow-green pleochroism. They show principal forms {001}, {100}, {010}, {110}, {110}, and prominent (100) cleavage traces. The Mohs hardness is 2-3 and the measured density is 3.620 g/cm 3 (calculated density is 3.616 g/cm 3 ). Crystals are biaxial negative and length slow, with RIs of alpha = 1.91, beta = 2.03, and gamma = 2.11, and 2V nearly equal 90 degrees . Chemical analysis yielded an empirical formula of Fe (super 3+) (sub 1.00) Mo (sub 2.01) W (sub 0.03) P (sub 0.02) O 10 H (sub 4.62) , calculated on the basis of ten O atoms. The simplified formula is Fe (super 3+) Mo 2 O 6 (OH) 3 .H 2 O, chosen on the basis of crystal-structure determination and Mossbauer spectroscopy results. Unit-cell parameters calculated both from the X-ray powder and single-crystal diffraction data are a = 5.889(5), b = 7.545(5), c = 9.419(5) Aa; alpha = 71.46(4) degrees , beta = 83.42(4) degrees ; gamma = 72.78(4) degrees ; V = 378.9(4) Aa 3 ; Z = 2; P1 or P1. The crystal structure was solved in P1 using direct methods and Fourier techniques. The final refinement based on 1486 observed reflections [I>2.00 sigma I] converged to R = 0.05 and R w = 0.038. The bamfordite crystal structure contains groups of four MoO 6 octahedra, linked by edge-sharing, which in turn are linked through corner-sharing to pairs of FeO 6 octahedra thereby forming infinite sheets parallel to (100). These sheets are stepped and linked by hydrogen bonding. No other molybdenum oxides have this or a similar structure, instead molybdates such as wulfenite, PbMoO 4 , are based on tetrahedrally coordinated molybdenum.

Wulfenite [lead(II) molybdate(VI)] is known as a scheelite structure in the I41/a space group. The structure of the unusual `hemimorphic' wulfenite crystals from the Mežica mine was refined in the noncentrosymmetric space group I\overline{4} using a Pb/Mo exchange disorder model with the approximate com­position Pb0.94Mo0.06[MoO4]. Pb atoms in the 2b positions are substituted by Mo at about 12%. The crystal is shown to be twinned by inversion. Hemimorphism may result from the short-range chemical ordering of the metal atoms at the 2b positions.

Joesmithite is a complex clinoamphibole which contains at least 14 components in its formula. Its ideal formula would be PbCa2 Mg3 Fe 2 3+ (Si6Be2O22) (OH)2. It is monoclinic holosymmetric, an ordered derivative of theC2/m clinoamphiboles,a = 9.915(2),b = 17.951(4),c = 5.243(1)A,β = 105.95(2)°, Z = 2, space groupP2/a, D(obs) = 3.83(1), D(cal) = 3.91 g cm-3. R = 0.056 for 2299 independent F0. The cells of joesmithite and pargasitic amphibole were compared according to differences, Δ, in their structure cells. The same procedure was applied to the margarosanite, PbCa2Si3O9 and walstromite, BaCa2Si3O9 pairs. In both pairs, the anion positions differed by 0.2 A at most, but the Pb/A, Pb/Ba differences ranged from 0.4 to 0.6 A. The lone pair Pb2+ cation responds according to the bond valence sums of its coordinating anions compared with its closed core counterpart. It appears that when the bond valence sums for the coordinating anions are different, Pb2+ moves toward the most underbonded anion. If the anion bond valence sums are equal for all vertices of the coordinating polyhedron (as in wulfenite, Pb2+Mo6+O4), then Pb2+ does not shift.

Thorneite, Pb_6(Te_2^(6+)O_(10))(CO_3)Cl_2(H_2O), is a new tellurate from Otto Mountain near Baker, California, named in honor of Brent Thorne. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins. Thorneite is directly associated with acanthite, cerussite, gold, hessite, iodargyrite, khinite, wulfenite, and three other new tellurates: housleyite, markcooperite, and ottoite. Various other secondary minerals occur in the veins, including three other new secondary tellurium minerals: paratimroseite, telluroperite, and timroseite. Thorneite is monoclinic, space group C2/c, a = 21.305(1), b = 11.059(1), c = 7.564(1) A, β = 101.112(4)°, V = 1748.8(4) A^3, and Z = 4. Crystals are prismatic to bladed with elongation and striations parallel to c and typically occur in parallel and random aggregates. It is yellow and transparent, with pale yellow streak and adamantine luster. Mohs hardness is estimated at 2. The mineral is brittle, with an irregular to splintery fracture and good {100} cleavage. The calculated density is 6.828 g/cm^3. Thorneite is biaxial (+), with large 2V, but indices of refraction are too high to be measured. The optic orientation is Y = b, Z ^ a = 29° in obtuse β. No pleochroism was observed. Electron microprobe analysis provided PbO 73.90, ZnO 0.03, TeO_3 20.35, Cl 2.29, H_2O 1.28 (structure), CO_2 2.29 (structure), O≡Cl –0.52, total 99.62 wt%; the empirical formula (based on O+Cl = 16) is (Pb_(5.94)Zn_(0.01))(Te_(2.08)^(6+)O_(10))(C_(1.00)O_3)[Cl_(1.16)O_(0.34)(OH)_(0.50)](H_2O). The strongest powder X-ray diffraction lines are [d_(obs) in A (hkl) I]: 10.43 (200) 35, 3.733 (5[overbar]11, 2[overbar]02, 002) 27, 3.595 (4[overbar]21) 33, 3.351 (112) 66, 3.224 (511, 131) 100, 3.093 (2[overbar]22, 3[overbar]31) 30, 2.900 (6[overbar]21) 44, 2.133 (821, 622, 223, 731, 242) 38. The crystal structure (R_1 = 0.028) contains edge-sharing octahedral tellurate dimers, [Te_2^(6+)O_(10)]^(8–) that bond to Pb atoms, which in turn are linked via bonds to Cl atoms, CO_3 triangles, and H_2O molecules.

Timroseite, Pb_2Cu_5^(2+)(Te^(6+)O_6)_2(OH)_2, and paratimroseite, Pb_2Cu_4^(2+)(Te^(6+)O_6)_2(H_2O)_2, are two new tellurates from Otto Mountain near Baker, California. Timroseite is named in honor of Timothy (Tim) P. Rose and paratimroseite is named for its relationship to timroseite. Both new minerals occur on fracture surfaces and in small vugs in brecciated quartz veins. Timroseite is directly associated with acanthite, cerussite, bromine-rich chlorargyrite, chrysocolla, gold, housleyite, iodargyrite, khinite-4O, markcooperite, ottoite, paratimroseite, thorneite, vauquelinite, and wulfenite. Paratimroseite is directly associated with calcite, cerussite, housleyite, khinite-4O, markcooperite, and timroseite. Timroseite is orthorhombic, space group P2_1nm, a = 5.2000(2), b = 9.6225(4), c = 11.5340(5) A, V = 577.13(4) A^3, and Z = 2. Paratimroseite is orthorhombic, space group P2_12_12_1, a = 5.1943(4), b = 9.6198(10), c = 11.6746(11) A, V = 583.35(9) A^3, and Z = 2. Timroseite commonly occurs as olive to lime green, irregular, rounded masses and rarely in crystals as dark olive green, equant rhombs, and diamond-shaped plates in subparallel sheaf-like aggregates. It has a very pale yellowish green streak, dull to adamantine luster, a hardness of about 2 1/2 (Mohs), brittle tenacity, irregular fracture, no cleavage, and a calculated density of 6.981 g/cm^3. Paratimroseite occurs as vibrant "neon" green blades typically intergrown in irregular clusters and as lime green botryoids. It has a very pale green streak, dull to adamantine luster, a hardness of about 3 (Mohs), brittle tenacity, irregular fracture, good {001} cleavage, and a calculated density of 6.556 g/cm^3. Timroseite is biaxial (+) with a large 2V, indices of refraction > 2, orientation X = b, Y = a, Z = c and pleochroism: X = greenish yellow, Y = yellowish green, Z = dark green (Z > Y > X). Paratimroseite is biaxial (–) with a large 2V, indices of refraction > 2, orientation X = c, Y = b, Z = a and pleochroism: X = light green, Y = green, Z = green (Y = Z >> X). Electron microprobe analysis of timroseite provided PbO 35.85, CuO 29.57, TeO_3 27.75, Cl 0.04, H_2O 1.38 (structure), O≡Cl –0.01, total 94.58 wt%; the empirical formula (based on O+Cl = 14) is Pb_(2.07) Cu^(2+)_(4.80)Te^(6+)_(2.04)O_(12)(OH)_(1.98)Cl_(0.02). Electron microprobe analysis of paratimroseite provided PbO 36.11, CuO 26.27, TeO_3 29.80, Cl 0.04, H_2O 3.01 (structure), O≡Cl –0.01, total 95.22 wt%; the empirical formula (based on O+Cl = 14) is Pb_(1.94)Cu^(2+)_(3.96)Te^(6+)_(2.03)O_(12)(H_2O)_(1.99)Cl_(0.01). The strongest powder X-ray diffraction lines for timroseite are [d_(obs) in A (hkl) I]: 3.693 (022) 43, 3.578 (112) 44, 3.008 (023) 84, 2.950 (113) 88, 2.732 (130) 100, 1.785 (multiple) 33, 1.475 (332) 36; and for paratimroseite 4.771 (101) 76, 4.463 (021) 32, 3.544 (120) 44, 3.029 (023,122) 100, 2.973 (113) 48, 2.665 (131) 41, 2.469 (114) 40, 2.246 (221) 34. The crystal structures of timroseite (R_1 = 0.029) and paratimroseite (R_1 = 0.039) are very closely related. The structures are based upon edge- and corner-sharing sheets of Te and Cu polyhedra parallel to (001) and the sheets in both structures are identical in topology and virtually identical in geometry. In timroseite, the sheets are joined to one another along c by sharing the apical O atoms of Cu octahedra, as well as by sharing edges and corners with an additional CuO_5 square pyramid located between the sheets. The sheets in paratimroseite are joined only via Pb-O and H bonds.

Ottoite, Pb_2TeO_5, is a new tellurate from Otto Mountain near Baker, California. Most of the mining on Otto Mountain occurred between 1940 and 1970 and is attributed to Otto Fuetterer, for whom the mountain is now named. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins, which intersect granitic rocks. Ottoite is directly associated with acanthite, bromine-rich chlorargyrite, gold, iodargyrite, khinite, wulfenite, and four other new tellurates: housleyite, markcooperite, thorneite, and timroseite. Various other secondary minerals occur in the veins, including two other new secondary tellurium minerals, paratimroseite and telluroperite. Ottoite and most other secondary minerals of the quartz veins are interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of the veins. A later generation of quartz mineralization then recemented the breccias, effectively isolating and protecting the secondary mineralization from further alteration. Ottoite is monoclinic, space group I2/a, with the unit cell: a = 7.5353(6), b = 5.7142(5), c = 10.8981(12) Å, β = 91.330(6)°, V = 469.13(8) Å^3, and Z = 4. The mineral occurs as complex spear-shaped crystals in subparallel to divergent intergrowths. It is yellow and transparent to translucent, with a pale yellow streak and adamantine luster. Mohs hardness is estimated at 3. The mineral is brittle, with an irregular fracture and two cleavages in the [100] zone at ~90°—possibly on {010} and {001}. The calculated density is 8.721 g/cm^3. Ottoite is biaxial (–), with a large 2V, but indices of refraction are too high to be measured. The optic orientation could only partially be determined: Y ≈ a. No pleochroism was observed. Electron microprobe analyses provided the following averages: PbO 68.88 and TeO_3 28.03, total 96.95 wt%; the empirical formula (based on O = 5) is Pb_(1.96)Te_(1.01)^(6+)O_5. The strongest powder X-ray diffraction lines are [d_(obs) in Å (hkl) I]: 3.131 (202) 64, 3.055 (013) 90, 3.015 (211) 100, 2.112 (222) 29, 1.810 (006, 215) 21, 1.773 (411, 402) 43, 1.686 (033, 231) 20. The crystal structure (R_1 = 0.020) consists of straight chains of trans-corner-sharing Te^(6+)O_6 octahedra parallel to a, which are joined by bonds to Pb atoms. The Pb atom exhibit markedly lopsided 11-coordination, typical of Pb^(2+) with stereoactive 6s^2 lone-pair electrons. The powder X-ray diffraction pattern of ottoite is very similar to that reported for girdite. Examination of girdite type material suggests that its description was based upon data obtained from at least two and possibly three different phases, one of which may correspond to ottoite.

The new mineral sardignaite, a bismuth molybdate with formula BiMo2O7(OH)·2H2O, occurs in quartz veins within a granitic rock at Su Senargiu, near Sarroch, Sardegna, Italy. The name is after the locality. Sardignaite occurs a thin prismatic crystals up to 1 mm in length, with pale yellow color and a white streak. It is transparent with adamantine lustre, non fluorescent, and brittle with a conchoidal fracture. It is associated with bismuthinite, bismoclite, molybdenite, ferrimolybdite, koechlinite, wulfenite, and the new mineral IMA 2009–022. Mohs hardness is ca. 3. D calc is 4.82 g/cm3. The mineral is monoclinic, space group P21/m, with a 5.7797(7), b 11.567(1), c 6.3344(8) A, β 113.360(9)°, V 388.8(1) A3. The strongest lines in the powder X-ray diffraction pattern are d(I)(hkl): 3.206(100)(031), 5.03(80)(−101), 1.992(45)(221), 3.120(32)(130). The crystal structure of sardignaite was solved to R(F) 0.056 using single-crystal X-ray diffraction data, and is characterized by edge-sharing dimers of [MoO5(H2O)] octahedra, linked to each other through corner-sharing to give rise to corrugated columns running along b. Such columns are held together by Bi3+ cations, eight-fold coordinated by 7 O + 1 (OH). Both the mineral and its name were approved by the IMA-CNMNC.

The new mineral plumbophyllite, Pb2Si4O10·H2O, orthorhombic with space group Pbcn and cell parameters a = 13.2083(4), b = 9.7832(3), c = 8.6545(2) A, V = 1118.33(5) A^3, and Z = 4. It occurs as colorless to pale blue prismatic crystals to 3 mm, with wedge-shaped terminations at the Blue Bell claims, about 11 km west of Baker, San Bernardino County, California. It is found in narrow veins in a highly siliceous hornfels in association with cerussite, chrysocolla, fluorite, goethite, gypsum, mimetite, opal, plumbotsumite, quartz, sepiolite, and wulfenite. The streak is white, the luster is vitreous, the Mohs hardness is about 5, and there is one perfect cleavage, {100}. The measured density is 3.96(5) g/cm^3 and the calculated density is 3.940 g/cm^3. Optical properties (589 nm): biaxial (+), {alpha} = 1.674(2), β = 1.684(2), {gamma} = 1.708(2), 2V = 66(2)°, dispersion r > v (strong); X = b, Y = c, Z = a. Electron microprobe analysis provided PbO 60.25, CuO 0.23, SiO_2 36.22 wt%, and CHN analysis provided H_2O 3.29 wt% for a total of 99.99 wt%. Powder IR spectroscopy confirmed the presence of H_2O and single-crystal IR spectroscopy indicated the H_2O to be oriented perpendicular to the b axis. Raman spectra were also obtained. The strongest powder X-ray diffraction lines are [d (hkl) I]: 7.88(110)97, 6.63(200)35, 4.90(020)38, 3.623(202)100, 3.166(130)45, 2.938(312/411/222)57, 2.555(132/213)51, and 2.243(521/332)50. The atomic structure (R1 = 2.04%) consists of undulating sheets of silicate tetrahedra between which are located Pb atoms and channels containing H_2O (and Pb^(2+) lone-pair electrons). The silicate sheets can be described as consisting of zigzag pyroxene-like (SiO_3)_n chains joined laterally into sheets with the unshared tetrahedral apices in successive chains pointed alternately up and down, a configuration also found in pentagonite.

High-pressure Raman scattering measurements have been performed in wulfenite (PbMoO4) for both bulk and nanocrystalline powders up to 22 GPa. Our Raman scattering measurements evidence the phase transition from the tetragonal scheelite structure to the monoclinic M-fergusonite structure in both bulk and nanocrystalline powders above 10.8 and 13.4 GPa, respectively. The pressure dependences of the Raman active modes in both structures were compared and discussed based on our theoretical results obtained from lattice dynamics ab initio calculations. © 2012 American Institute of Physics., Financial support from the Spanish ConsoliderIngenio 2010 Program (Project No. CDS2007-00045) is acknowledged. The work was also supported by Spanish MICINN under Projects MAT2010-21270-C04-01/03/04 and from Vicerrectorado de Investigacion de la Universitat Politecnica de Valencia under Projects UPV2011-0914PAID-05-11 and UPV2011-0914 PAID-05-11. Supercomputer time has been provided by the Red Espanola de Supercomputacion (RES) and the MALTA cluster.

A study of the morphology of chalcopyrite, stannite, wulfenite and manganite shows that the existence of a structural pseudo-symmetry has an influence on the relative importance of the different forms in these crystals. In particular, the reticular planes possessing, in relation to the pseudo-symmetry, a spacing which is a submultiple of the true spacing correspond to forms whose development is in general less common than that predicted by the law of Donnay & Harker.

A new approach for seeking PBC's applicable to every known structure has been applied to the wulfenite structure. The following PBC's have been analyzed: straight - [110], [021] and [001], and zigzag chains - [100], [111], [131], [331], [011], and their symmetrical equivalents. It is established through a comparison with the zone development of the crystals with scheelite type structure that all chains determined and no others, effect the morphology. The chains are also distinguished according to the distances between the neighbouring metal Pb and Mo bound with oxygen. Chains within which this distance is shortest, i.e. 3.84 A only determine a single F-form {001}, the F-forms {011}, {112}, {013} and {010} are added for chains which have a distance of 4.10 A. If all chains derived are taken into account, {121} and {110} become F-forms, too. The morphological variations of the crystals with scheelite type structure are also analyzed using the PBC method.

n/a

n/a