ALBERT

Description: Schlemaite, with the simplified formula (Cu,{square})6(Pb,Bi)Se4, is a new mineral species from the Niederschlema-Alberoda vein-type uranium deposit at Hartenstein, Erzgebirge, Germany. It occurs as anhedral to subhedral grains with no obvious forms or twinning, in aggregates of up to several hundred µm across, with berzelianite, eucairite and clausthalite in a dolomite-ankerite matrix. Schlemaite is black with a black streak and opaque with a metallic luster. It is brittle with an uneven fracture and no observable cleavage. It has a mean VHN (25 g load) of 106 kg/mm2, which roughly equates to a Mohs hardness of 3. In plane-polarized reflected light, schlemaite is grey, non-pleochroic with a very weak bireflectance. It has very weak anisotropy, with rotation tints in shades of very pale metallic orange and blue, and shows no internal reflections. Electron-microprobe analyses yielded a mean composition Cu 38.86, Ag 2.57, Au 0.07, Hg 0.09, Pb 13.75, Bi 9.12, Se 35.11, total 99.57 wt.%. The empirical formula (based on 4 Se apfu) is (Cu5.50Ag0.21){sum}5.71(Pb0.60Bi0.39){sum}0.99Se4. The calculated density is 7.54 g/cm3 (based on the empirical formula and unit-cell parameters refined from single-crystal data). Schlemaite is monoclinic, P21/m, a 9.5341(8), b 4.1004(3), c 10.2546(8) Å, ß 100.066(2)°, V 394.72(9) Å3, a:b:c 2.3252:1:2.5009, Z = 2. The crystal structure of schlemaite was solved by direct methods and refined to an R index of 4.8% using 1303 unique reflections collected on a four-circle diffractometer equipped with a CCD detector. The structure consists of intercalated ordered and disordered layers. The ordered layer consists of ladders of Pb2+ + Bi3+ coordinated by Se, the former showing strong lone-pair-stereoactive effects, and a network of Cu+ coordinated by Se anions. The disordered layer consists of an array of sites partly occupied by Cu+ and Ag+ in a variety of coordinations, and is characterized by strong short-range order. The strongest seven lines of the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are:3.189(100)(012), 3.132(100)(Formula12), 2.601(70)(Formula13), 2.505(50)(Formula11), 2.151(60)(014), 2.058(80)(020) and 1.909(50)(Formula14). Although schlemaite is chemically similar to furutobeite, (Cu,Ag)6PbS4, it is not isostructural with it. The mineral is named after the Schlema-Alberoda uranium ore field near Schneeberg in the ancient mining region of Saxony, Germany.

Description: Khvorovite, ideally $${\mathrm{Pb}}_{4}^{2+}$$ Ca 2 [Si 8 B 2 (SiB)O 28 ]F, is a new borosilicate mineral of the hyalotekite group from the Darai-Pioz alkaline massif in the upper reaches of the Darai-Pioz river, Tajikistan. Khvorovite was found in a pectolite aggregate in silexites (quartz-rich rocks). The pectolite aggregate consists mainly of pectolite, quartz and fluorite, with minor aegirine, polylithionite, turkestanite and baratovite; accessory minerals are calcite, pyrochlore-group minerals, reedmergnerite, stillwellite-(Ce), pekovite, zeravshanite, senkevichite, sokolovaite, mendeleevite-(Ce), alamosite, orlovite, leucosphenite and several unknown Cs-silicates. Khvorovite occurs as irregular grains, rarely with square or rectangular sections up to 150 μm, and grain aggregates up to 0.5 mm. Khvorovite is colourless, rarely white, transparent with a white streak, has a vitreous lustre and does not fluoresce under ultraviolet light. Cleavage and parting were not observed. Mohs hardness is 5–5.5, and khvorovite is brittle with an uneven fracture. The measured and calculated densities are 3.96(2) and 3.968 g/cm 3 , respectively. Khvorovite is biaxial (+) with refractive indices ( = 589 nm) α = 1.659(3), β calc. = 1.671(2), = 1.676(3); 2V meas. = 64(3)°, medium dispersion: r 〈 v . Khvorovite is triclinic, space group I 1I, a = 11.354(2), b = 10.960(2), c = 10.271(2) Å, α = 90.32(3), β = 90.00(3), = 90.00(3)°, V = 1278(1) Å 3 , Z = 2. The six strongest lines in the powder X-ray diffraction pattern [ d (Å), I, ( hkl )] are: 7.86, 100, (110); 7.65, 90, (1I01); 7.55, 90, (011); 3.81, 90, (202); 3.55, 90, (301); 2.934, 90, (3I12, 312). Chemical analysis by electron microprobe gave SiO 2 36.98, B 2 O 3 6.01, Y 2 O 3 0.26, PbO 40.08, BaO 6.18, SrO 0.43, CaO 6.77, K 2 O 1.72, Na 2 O 0.41, F 0.88, O=F –0.37, sum 99.35 wt.%. The empirical formula based on 29 (O+F) a.p.f.u. is ( $${\mathrm{Pb}}_{2.76}^{2+}$$ Ba 0.62 K 0.56 Na 0.16 ) 4.10 (Ca 1.86 Sr 0.06 Y 0.04 Na 0.04 ) 2 [Si 8 B 2 (Si 1.46 B 0.65 ) 2.11 O 28 ](F 0.71 O 0.29 ), Z = 2, and the simplified formula is (Pb 2+ ,Ba,K) 4 Ca 2 [Si 8 B 2 (Si,B) 2 O 28 ]F. The crystal structure of khvorovite was refined to R 1 = 2.89% based on 3680 observed reflections collected on a four-circle diffractometer with Mo K α radiation. In the crystal structure of khvorovite, there are four [4]-coordinated Si sites occupied solely by Si with 〈Si–O〉 = 1.617 Å. The [4]-coordinated B site is occupied solely by B, with 〈B–O〉 = 1.478 Å. The [4]-coordinated T site is occupied by Si and B (Si 1.46 B 0.54 ), with 〈T–O〉 = 1.605 Å; it ideally gives (SiB) a.p.f.u. The Si, B and T tetrahedra form an interrupted framework of ideal composition [Si 8 B 2 (SiB)O 28 ] 11– . The interstitial cations are Pb 2+ , Ba and K (minor Na) [ A (11–22) sites] and Ca [ M site]. The two A sites are each split into two subsites ~0.5 Å apart and occupied by Pb 2+ and Ba + K. The [8]-coordinated M site is occupied mainly by Ca, with minor Sr, Y and Na. Khvorovite is a Pb 2+ -analogue of hyalotekite, (Ba,Pb 2+ ,K) 4 (Ca,Y) 2 [Si 8 (B,Be) 2 (Si,B) 2 O 28 ]F and a Pb 2+ -, Ca-analogue of kapitsaite-(Y), (Ba,K) 4 (Y,Ca) 2 [Si 8 B 2 (B,Si) 2 O 28 ]F. It is named after Pavel V. Khvorov (b. 1965), a Russian mineralogist, to honour his contribution to the study of the mineralogy of the Darai-Pioz massif.

Description: Far-infrared spectroscopy and X-ray powder diffraction Rietveld structure refinement for the hydrothermal synthetic muscovite series, (a) KAl 3 (Si 3–y Ge y )O 10 (OH,OD) 2 , (b) KGa 3 (Si 3–y Ge y )O 10 (OH,OD) 2 , and (c) K(Al 3–x Ga x )Ge 3 O 10 (OH,OD) 2 , where x = 0.0–3.0, y = 0.0–3.0, and the muscovite–tobelite series, (d) [K 1–A (NH 4 ,ND 4 ) A ]Al 3 Si 3 O 10 (OH,OD) 2 , where A = 0.0–1.0, indicate that there is a complete solid-solution in each series. In the 200–50 cm –1 far-infrared region, four kinds of bands are observed: two bands due to octahedral deformation coupled with OH deformational vibrations between 240 and 130 cm –1 , an in-plane tetrahedral torsional band between 175 and 130 cm –1 , an interlayer I–O inner stretching band, and an I–O outer stretching band. The weak and broad 140 cm –1 band is assigned to K–O inner stretching and the strong broad 110 cm –1 band to K–O outer stretching in muscovite. The broad 175 cm –1 band is (NH 4 /ND 4 )–O inner stretching and the 140 cm –1 broad strong band is (NH 4 /ND 4 )–O outer stretching in tobelite. With increasing Ga-〉Al substitution, the I–O inner and I–O outer stretching bands shift to lower frequency, while with increasing Ge-〉Si substitution, the I–O inner stretching band shifts to higher frequency; the I–O outer stretching bands do not change as a function of composition.

Description: Carlfrancisite, Mn 3 2+ (Mn 2+ ,Mg,Fe 3+ ,Al) 42 (As 3+ O 3 ) 2 (As 5+ O 4 ) 4 [(Si,As 5+ )O 4 ] 6 [(As 5+ ,Si)O 4 ] 2 (OH) 42 , is a new mineral from the Kombat mine, Otavi Valley, Namibia, and occurs as curved platy aggregates ~2 cm across on a matrix of Mn arsenates and oxides. It is yellowy orange to pale yellow with a very pale-yellow streak, translucent with a vitreous to opalescent luster, and does not fluoresce under ultraviolet light. Cleavage is micaceous on {001}, and no parting or twinning was observed. Mohs hardness is 3, and carlfrancisite is brittle with a hackly fracture. The calculated density is 3.620 g/cm 3 . Optical properties were measured with a Bloss spindle stage for the wavelength 590 nm using a gel filter. The indices of refraction are = 1.756, = 1.758, and it is non-pleochroic. Carlfrancisite is trigonal, space group R c , a = 8.2238(2), c = 205.113(6) Å, V = 12013.5(4) Å 3 , Z = 6, c:a = 1:24.941. The seven strongest lines in the X-ray powder-diffraction pattern are as follows: d (Å), I , ( hkl ): 2.826, 100, ( 2 44); 2.371, 88, ( 3 40, 3 41); 1.552, 84, ( 5 0); 2.676, 63, ( 3 7); 3.243, 54, (0 1 56, 2 39); 4.107, 48, ( 2 0); 2.918, 47, (0 2 40). Chemical analysis by electron microprobe and crystal-structure refinement gave As 2 O 5 13.07, As 2 O 3 3.18, P 2 O 5 0.50, V 2 O 5 0.74, SiO 2 8.96, Al 2 O 3 0.78, FeO 0.22, MnO 53.25, MgO 9.37, H 2 O(calc) 8.42, sum 98.49 wt%. The H 2 O content and the valence states of As were determined by crystal-structure analysis. The empirical formula is Mn 2+ 33.55 Mg 10.39 Fe 2+ 0.14 Al 0.68 As 3+ 1.44 (Si 6.67 P 0.32 V 5+ 0.37 As 5+ 5.08 )O 54 (OH) 42 on the basis of 96 anions with (OH) = 42 apfu. The structure of carlfrancisite is closely related to that of mcgovernite and turtmannite.

Description: Pieczkaite, ideally Mn 5 (PO 4 ) 3 Cl, is a new apatite-supergroup mineral from Cross Lake, Manitoba, Canada. It occurs as small patches and narrow veins in large crystals of apatite and (Mn,Cl)-bearing apatite in phosphate pods in the quartz core of a granitic pegmatite. Veins of Mn-bearing apatite narrow to ~25 μm where the Mn content becomes high enough to constitute pieczkaite. It is gray with a grayish-white streak, does not fluoresce under ultraviolet light, and has no observable cleavage or parting. Mohs hardness is 4–5, and pieczkaite is brittle with an irregular fracture. The calculated density is 3.783 g/cm 3 . Optical properties were measured using a Bloss spindle stage at a wavelength of 590 nm (using a gel filter). Pieczkaite is uniaxial (–) with indices of refraction = 1.696, = 1.692, both ±0.002. Pieczkaite is hexagonal, space group P 6 3 / m , a = 9.504(4), c = 6.347(3) Å, V = 496.5(1) Å 3 , Z = 2, c : a = 1:0.6678. The six strongest lines in the X-ray powder diffraction pattern are as follows: d (Å), I , ( hkl ): 2.794, 100, (31, 31); 2.744, 88, (030); 2.639, 34, (22); 2.514, 25, (031, 022); 1.853, 25, (42, 42); 3.174, 24, (002). Chemical analysis by electron microprobe gave P 2 O 5 37.52, MnO 41.77, FeO 2.45, CaO 13.78, Cl 3.86, H 2 O 0.60, OCl –0.87, sum 99.11 wt% where the H 2 O content was calculated as 1 – Cl apfu. The resulting empirical formula on the basis of 12 O anions is (Mn 3.36 Fe 0.20 Ca 1.40 ) 4.96 (P 1.01 O 4 ) 3 (Cl 0.62 OH 0.38 ) 1.00 , and the end-member formula is Mn 5 (PO 4 ) 3 Cl. The crystal structure of pieczkaite was refined to an R 1 index of 4.07% based on 308 observed reflections collected on a three-circle rotating-anode diffractometer with Mo K α X-radiation. Pieczkaite is isostructural with apatite, Mn is the dominant cation at both the [9]- and [7]-coordinated-cation sites in the structure, and Cl is the dominant monovalent anion.

Description: Magnesio-arfvedsonite, the C Fe 3+ -dominant analogue of eckermannite, has been found in a sample of "szechenyite" in the mineral collection of the American Museum of Natural History (AMNH H35024). It comes from the northern part of the Jade Mine Tract near Hpakan, Kachin State, Myanmar. Associated minerals are kosmochlor–jadeite solid-solution pyroxene and clinochlore. The ideal formula of magnesio-arfvedsonite is A Na B Na 2 C (Mg 4 Fe 3+ ) T Si 8 O 22 W (OH) 2 , and the empirical formula derived from electron microprobe analysis and single-crystal structure refinement for the sample of this work is A (Na 0.96 K 0.04 ) =1.00 B (Na 1.57 Ca 0.40 $${\mathrm{Fe}}_{0.02}^{2+}$$ Mn 0.01 ) =2.00 C (Mg 4.26 $${\mathrm{Fe}}_{0.19}^{2+}$$ $${\mathrm{Fe}}_{0.41}^{3+}$$ Al 0.11 $${\mathrm{Ti}}_{0.03}^{4+}$$ ) =5.00 T (Si 7.99 Al 0.01 ) =8.00 O 22 W [F 0.02 (OH) 1.98 ] =2.00 . The unit-cell dimensions are a = 9.867(1), b = 17.928(2), c = 5.284(1) Å, β = 103.80(2)°, V = 907.7 (2) Å 3 , Z = 2. Magnesio-arfvedsonite is biaxial (–), with α = 1.624, β = 1.636, = 1.637, all ± 0.002 and 2V obs = 36(1)°, 2V calc = 32°. The ten strongest reflections in the X-ray powder pattern [ d values (in Å), I , ( hkl )] are: 2.708, 100, (151); 3.399, 68, (131); 3.144, 63, (310); 2.526, 60, (2I02); 8.451, 46, (110); 3.273, 39, (240); 2.167, 37, (261); 2.582, 34, (061); 2.970, 34, (221); 2.326, 33, [(2I51) (4I21)].

Description: The crystal-chemical characterization of an amphibole with an unusual composition, A (Na 0.76 K 0.24 ) B (Ca 1.42 Na 0.56 Mn 2+ 0.02 ) C (Mg 2.64 Fe 2+ 1.95 Mn 2+ 0.07 Mg 2.64 Zn 0.01 Fe 3+ 0.01 Ti 4+ 0.32 ) T (Si 7.18 Al 0.82 )O 22 W [(OH) 0.58 O 0.27 F 1.15 ], found in pegmatitic veins at Kariåsen, Larvik Plutonic Complex, Norway, provides an excellent example of the detection and estimation of the oxo component in amphibole. The use of Ti as a proxy for the oxo component is discussed and a procedure to derive accurate Ti partitioning from the results of structure refinement is described. Because the presence and amount of oxo component in amphiboles are important in order to determine values of f O 2 and f H 2 O , especially in igneous and magmatic systems, this procedure should be applied any time the compositional data or the petrological context indicate the presence of significant Ti, or suggest that the oxo component may be a relevant issue.

Description: A bstract The crystal structure of faheyite, ideally Mn 2+ Fe 3+ 2 [Be 2 (PO 4 ) 4 ](H 2 O) 6 , trigonal, a 9.404(7), c 15.920(11) Å, V 1219(2) Å 3 , Z = 3, space group P 3 1 21, has been solved and refined to an R 1 index of 4.4% with single-crystal X-ray diffraction data collected from a twinned fiber. There are two P sites that are tetrahedrally coordinated by O atoms with 〈 P –O〉 distances of 1.52 and 1.54 Å, respectively, one Be site tetrahedrally coordinated by O atoms with a 〈 Be –O〉 distance of 1.63 Å, one Mn site occupied by Mn 2+ coordinated by four O atoms and two (H 2 O) groups with a 〈 Mn –O〉 distance of 2.22 Å, and one Fe site occupied by Fe 3+ coordinated by four O atoms and two (H 2 O) groups with a 〈 Fe –O〉 distance of 2.01 Å. Each vertex of the Be tetrahedron is shared with a vertex of a neighboring P tetrahedron, and two vertices of each P tetrahedron are shared with neighboring Be tetrahedra to form a corner-sharing [Be(PO 4 ) 2 ] chain, with P tetrahedra flanking the Be tetrahedra of the central spine in the sequence - P (1)/ P (1)- Be - P (2)/ P (2)- Be -. Faheyite has a chiral structure, with the [Be(PO 4 ) 2 ] chain twisting about the c -axis in a clockwise direction for the refined P 3 1 21 enantiomer. The Mn octahedron lies along the 3 1 screw axis within the core region of the [Be(PO 4 ) 2 ] chain, forming [MnBe 2 (PO 4 ) 4 ] spires that are wrapped by Fe octahedra that share vertices with P tetrahedra. The crystal structures of fransoletite and parafransoletite also contain beryllophosphate chains topologically identical to that found in faheyite, although the [Be(PO 4 )(PO 3 OH)] chain in fransoletite and parafransoletite is straight, whereas the [Be(PO 4 ) 2 ] chain in faheyite forms a helix about the central c -axis.

Description: The crystal structure of betalomonosovite, ideally Na 6 4 Ti 4 (Si 2 O 7 ) 2 [PO 3 (OH)][PO 2 (OH) 2 ]O 2 (OF), a 5.3331(7), b 14.172(2), c 14.509(2) Å, α 103.174(2), β 96.320(2), 90.278(2)°, V 1060.7(4) Å 3 , from the Lovozero alkaline massif, Kola peninsula, Russia, has been refined in the space group P 1{macron} to R = 6.64% using 3379 observed ( F o 〉 4 F ) reflections collected with a single-crystal APEX II ULTRA three-circle diffractometer with a rotating-anode generator (Mo K α), multilayer optics, and an APEX-II 4K CCD detector. Electron-microprobe analysis gave the empirical formula (Na 5.39 Ca 0.36 Mn 0.04 Mg 0.01 ) 5.80 (Ti 2.77 Nb 0.48 Mg 0.29 Fe 3+ 0.23 Mn 0.20 Zr 0.02 Ta 0.01 ) 4 (Si 2.06 O 7 ) 2 [P 1.98 O 5 (OH) 3 ]O 2 [O 0.82 F 0.65 (OH) 0.53 ] 2 , D calc. = 2.969 g cm –3 , Z = 2, calculated on the basis of 26 (O + F) apfu , with H 2 O determined from structure refinement. The crystal structure of betalomonosovite is characterized by extensive cation and anion disorder: more than 50% of cation sites are partly occupied. The crystal structure of betalomonosovite is a combination of a titanium silicate (TS) block and an intermediate ( I ) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral) and exhibits linkage and stereochemistry typical for Group IV (Ti + Mg + Mn = 4 apfu ) of the TS-block minerals. The I block is a framework of Na polyhedra and P tetrahedra which ideally gives {Na 2 4 [PO 3 (OH)][PO 2 (OH) 2 ]} pfu . Betalomonosovite is an Na-poor OH-bearing analogue of lomonosovite, Na 10 Ti 4 (Si 2 O 7 ) 2 (PO 4 ) 2 O 4 . In the betalomonosovite structure, there is less Na in the I block and in the TS block when compared to the lomonosovite structure. The OH groups occur mainly in the I block where they coordinate P and Na atoms and in the O sheet of the TS block (minor). The presence of OH groups in the I block and in the TS block is supported by IR spectroscopy and bond-valence calculations on anions. High-resolution TEM of lomonosovite shows the presence of pervasive microstructural intergrowths, accounting for the presence of signals from H 2 O in the infrared spectrum of anhydrous lomonosovite. More extensive lamellae in betalomonosovite suggest a topotactic reaction from lomonosovite to betalomonosovite.

Description: The crystal structure of pargasite from a cut gem from Myanmar, (K 0.094 Na 0.93 )(Na 0.15 Ca 1.78 )(Mg 4.51 Fe 2+ 0.02 Al 0.53 Ti 0.10 )(Si 6.56 Al 1.44 )O 22 (OH 1.32 F 0.68 ), a 9.882(6), b 17.973(11), c 5.282(3) Å, β 105.20(1)°, V 905.33(17) Å 3 , space group C2/m , Z = 2, has been refined to an R 1 index of 1.9% using Mo K α single-crystal X-ray diffraction. The unit formula (calculated from the results of electron-microprobe analysis), the refined site-scattering values, and the observed mean bond-lengths, were used to assign site populations. [4] Al occurs at both the T (1) and T (2) sites, but is strongly ordered at T (1). [6] Al is disordered over the M (2) and M (3) sites, but is excluded from the M (1) site. A Na is split between the A (2) and A ( m ) sites with minor K assigned to the A ( m ) site. The frequencies of short-range ion arrangements over the configuration symbol M (1) M (1) M (3)–O(3)– A : T (1) T (1) were calculated from the refined site-populations and are in reasonable accord with the fitted infrared spectrum of this amphibole in the principal OH-stretching region.