Neil A. Ball

Maruyamaite, K(MgAl2)(Al5Mg)Si6O18(BO3)3(OH)3O, a potassium-dominant tourmaline from the ultrahigh-pressure Kokchetav massif, northern Kazakhstan: Description and crystal structure

Abstract Maruyamaite, ideally K(MgAl2)(Al5Mg)Si6O18(BO3)3(OH)3O, was recently approved as the first K-dominant mineral-species of the tourmaline supergroup. It occurs in ultrahigh-pressure quartzofeldspathic gneisses of the Kumdy-Kol area of the Kokchetav Massif, northern Kazakhstan. Maruyamaite contains inclusions of microdiamonds, and probably crystallized near the peak pressure conditions of UHP metamorphism in the stability field of diamond. Crystals occur as anhedral to euhedral grains up to 2 mm across, embedded in a matrix of anhedral quartz and K-feldspar. Maruyamaite is pale brown to brown with a white to very pale-brown streak and has a vitreous luster. It is brittle and has a Mohs hardness of ∼7; it is non-fluorescent, has no observable cleavage or parting, and has a calculated density of 3.081 g/cm3. In plane-polarized transmitted light, it is pleochroic, O = darkish brown, E = pale brown. Maruyamaite is uniaxial negative, ω = 1.634, ε = 1.652, both ±0.002. It is rhombohedral, space group R3m, a = 15.955(1), c = 7.227(1) Å, V = 1593(3) Å3, Z = 3. The strongest 10 X-ray dif- fraction lines in the powder pattern are [d in Å(I)(hkl)]: 2.581(100)(051), 2.974(85)(1̄32), 3.995 (69)(2̄40), 4.237(59)(2̄31), 2.046(54)(1̄62), 3.498(42)(012), 1.923(36)(3̄72), 6.415(23)(1̄11), 1.595(22)(5̄.10.0), 5.002(21)(021), and 4.610(20)(030). The crystal structure of maruyamaite was refined to an R1 index of 1.58% using 1149 unique reflections measured with MoKα X-radiation. Analysis by a combination of electron microprobe and crystal-structure refinement gave SiO2 36.37, Al2O3 31.50, TiO2 1.09, Cr2O3 0.04, Fe2O3 0.33, FeO 4.01, MgO 9.00, CaO 1.47, Na2O 0.60, K2O 2.54, F 0.30, B2O3(calc) 10.58, H2O(calc) 2.96, sum 100.67 wt%. The formula unit, calculated on the basis of 31 anions pfu with B = 3, OH = 3.24 apfu (derived from the crystal structure) and the site populations assigned to reflect the mean interatomic distances, is (K0.53Na0.19Ca0.26□0.02)ΣX=1.00(Mg1.19Fe0.552+Fe0.053+

Fluoroleakeite, NaNa2(Mg2Li)Si8O22F2, a new mineral of the amphibole group from the Verkhnee Espe deposit, Akjailyautas Mountains, Eastern Kazakhstan District, Kazakhstan: description and crystal structure

{\rm{Fe}}_{0.55}^{2 + }{\rm{Fe}}_{0.05}^{3 + }

Krasnoite, the fluorophosphate analogue of perhamite, from the Huber open pit, Czech Republic and the Silver Coin mine, Nevada, USA

Ti0.14Al1.07)□Y=3.00(Al5.00Mg1.00)(Si5.97Al0.03O18)(BO3)3(OH)3(O0.602−

Ianbruceite, ideally [Zn2(OH)(H2O)(AsO4)](H2O)2, a new arsenate mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia: description and crystal structure

{\rm{O}}_{0.60}^{2 - }

Fluoro-sodic-ferropedrizite, NaLi2(\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{Fe}_{2}^{2+}\) \end{document}Al2Li)Si8O22F2, a new mineral of the amphibole group from the Sutlug River, Tuva Republic, Russia: description and crystal structure

F0.16OH0.24). Maruyamaite, ideally K(MgAl2) (Al5Mg)(BO3)3(Si6O18)(OH)3O, is related to oxy-dravite: ideally Na(MgAl2)(Al5Mg)(BO3)3(Si6O18)(OH)3O, by the substitution XK → XNa.

Fluoro-aluminoleakeite, NaNa2(Mg2Al2Li)Si8O22F2, a new mineral of the amphibole group from Norra Kärr, Sweden: description and crystal structure

Abstract Fluoroleakeite, NaNa2(Mg2Fe23+Li)Si8O22F2, is a new mineral of the amphibole group from the Verkhnee Espe deposit, Akjailyautas mountains, eastern Kazakhstan district, Kazakhstan. The granites and their host rocks have been intensely reworked by post-magmatic and host-rock fluids, resulting in intense recrystallization, enrichment in F, Li and rare elements, and replacement of primary biotite and sodic-calcic amphiboles by Li-bearing riebeckite, aegirine, astrophyllite and other sodic minerals including fluoroleakeite. Crystals are prismatic parallel to [001] with {100} and {110} faces and cleavage surfaces, and the prism direction is terminated by irregular fractures. Grains are up to 3 mm long, and occur as isolated crystals, as small aggregates, and as inclusions in cámaraite. Crystals are black with a very pale grey to colourless streak. Fluoroleakeite is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.245 g cm-3. In plane-polarized light, it is pleochroic, X = pale grey-green, Y = medium grey, Z = grey-brown; X^a = 14.1º (in β obtuse), Y ‖ b, Z^c = 75.9º (in β acute). Fluoroleakeite is biaxial negative, α = 1.663(2), β = 1.673(2), γ = 1.680(2); 2Vobs = 80.9(6)º, 2Vcalc = 79.4º Fluoro-leakeite is monoclinic, space group C2/m, a = 9.8927(3), b = 17.9257(6), c = 5.2969(2) Å, β = 103.990(1)º, V = 905.7(1) Å3, Z = 2. The strongest ten X-ray diffraction lines in the powder pattern are [d in Å(I)(hkl)]: 2.718(100)(151), 8.434(40)(110), 4.464(30)(021), 3.405(30)(131), 3.137(20)(310), 2.541(20)(2̄02), 2.166(20)(261), 2.325(15)(3̄51), 2.275(15)(3̄12) and 2.806(10)(330). Analysis by a combination of electron microprobe and crystal-structure refinement gives SiO2 53.34, Al2O3 0.62, TiO2 1.27, V2O3 0.05, Fe2O3 15.10, FeO 6.00, MnO 2.04, ZnO 0.18, MgO 6.40, CaO 0.13, Na2O 9.08, K2O 1.98, Li2O 1.10, F 3.33, H2Ocalc 0.16, sum 99.39 wt.%. The formula unit, calculated on the basis of 23 O, is A(Na0.64K0.38)(Na1.98Ca0.02)(Li0.66Mg1.42Fe0.752+Mn0.262+Zn0.02Fe1.693+V0.013+Ti0.144+Al0.03)(Si7.93Al0.07)O22(F1.57OH0.16O0.27). Crystal-structure refinement shows Li to be completely ordered at the M(3) site. Fluoroleakeite, ideally NaNa2(Mg2Fe23+Li)Si8O22F2, is related to end-member leakeite, NaNa2(Mg2Fe23+Li)Si8O22(OH)2 by the substitution F → (OH).

Eckermannite revised: The new holotype from the Jade Mine Tract, Myanmar—crystal structure, mineral data, and hints on the reasons for the rarity of eckermannite

Abstract Krásnoite is a new mineral (IMA2011-040) from the Huber open pit, Krásno ore district, Czech Republic and the Silver Coin mine, Nevada, USA. Krásnoite is the fluorophosphate analogue of perhamite. Krásnoite occurs as compact to finely crystalline aggregates, balls and rosette-like clusters up to 1 mm across. Individual crystals are platy, show a hexagonal outline and can reach 0.1 mm on edge at Krásno and 0.4 mm at Silver Coin. At both localities, krásnoite occurs very late in phosphaterich paragenetic sequences. Krásnoite crystals are partly transparent with a typically pearly lustre, but can also appear greasy (Krásno) or dull (Silver Coin). The streak is white and the hardness is 5 on the Mohs scale. Crystals are brittle, have an irregular fracture, one imperfect cleavage on {001} and are not fluorescent under SW and LW ultraviolet light. Penetration twinning ⊥ {001} is common. The density for both Krásno and Silver Coin material is 2.48(4) g cm-3, measured by the sink-float method in an aqueous solution of sodium polytungstate. The calculated density is 2.476 g cm-3 (Krásno). Krásnoite crystals are uniaxial (+), with ω = 1.548(2) and ε = 1.549(2) (Krásno) and ω = 1.541(1) and ε = 1.543(1) (Silver Coin). The simplified formula of krásnoite is: Ca3Al7.7Si3P4O23.5(OH)12.1F2·8H2O. Krásnoite is trigonal, space group P3̅m1, with a = 6.9956(4), c = 20.200(2) Å, V = 856.09(9) Å3 and Z = 3. Raman and infrared spectroscopy, coupled with magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectrometry, confirmed the presence of PO3F, PO4, SiO4, H2O and OH in the crystal structure of krásnoite.

Vladykinite, Na3Sr4(Fe2+Fe3+)Si8O24: A new complex sheet silicate from peralkaline rocks of the Murun complex, eastern Siberia, Russia

Abstract Ianbruceite, ideally [Zn2(OH)(H2O)(AsO4)](H2O)2, is a new supergene mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia. It occurs as thin platy crystals up to 80 μm long and a few mm thick, which form flattened aggregates up to 0.10 mm across, and ellipsoidal aggregates up to 0.5 mm across. It is associated with coarse white leiteite, dark blue köttigite, minor legrandite and adamite. Ianbruceite is sky blue to very pale blue with a white streak and a vitreous lustre; it does not fluoresce under ultraviolet light. It has perfect cleavage parallel to (100), is flexible, and deforms plastically. The Mohs hardness is 1 and the calculated density is 3.197 g cm-3. The refractive indices are α = 1.601, β = 1.660, γ = 1.662, all ±0.002; 2Vobs = 18(2)º, 2Vcalc = 20º, and the dispersion is r < v, weak. Ianbruceite is monoclinic, space group P21/c, a = 11.793(2), b = 9.1138(14), c = 6.8265(10) Å, β = 103.859(9)º, V = 712.3(3) Å3, Z = 4, a:b:c = 1.2940:1:0.7490. The seven strongest lines in the X-ray powder diffraction pattern [d (Å), I, (hkl)] are as follows: 11.29, 100, (100); 2.922, 17, (130); 3.143, 15, (2̄02); 3.744, 11, (300); 2.655, 9, (230); 1.598, 8, (1̄52); 2.252, 7, (222). Chemical analysis by electron microprobe gave As2O5 36.27, As2O3 1.26, Al2O3 0.37, ZnO 49.72, MnO 0.32, FeO 0.71, K2O 0.25, H2Ocalc 19.89, sum 108.79 wt.%; the very high oxide sum is due to the fact that the calculated H2O content is determined from crystal-structure analysis, but H2O is lost under vacuum in the electron microprobe. The crystal structure of ianbruceite was solved by direct methods and refined to an R1 index of 8.6%. The As is tetrahedrally coordinated by four O anions with a mean As-O distance of 1.687 Å. Zigzag [[5]Zn[6]Znφ7] chains extend in the c direction and are linked in the b direction by sharing corners with (AsO4) tetrahedra to form slabs with a composition [Zn2(OH)(H2O)(AsO4)]. The space between these slabs is filled with disordered (H2O) groups and minor lone-pair stereoactive As3+. The ideal formula derived from chemical analysis and crystal-structure solution and refinement is [Zn2(OH)(H2O)(AsO4)](H2O)2.

Agakhanovite-(Y), ideally (YCa)□2KBe3Si12O30, a new milarite-group mineral from the Heftetjern pegmatite, Tørdal, Southern Norway: Description and crystal structure

Abstract Fluoro-sodic-ferropedrizite, ideally ANaBLi2 C(Fe2+2 Al2Li)TSi8O22WF2, is a new mineral of the amphibole group from the Sutlug River, Tuva Republic, Russia. It occurs at the endogenic contact of a Li-pegmatite with country rocks near to a diabase dyke and formed by reaction of the pegmatitic melt with the country rock. Fluoro-sodic-ferropedrizite occurs as prismatic to acicular crystals, ranging in length from 0.1−3 cm and widths of up to 50 μm. Crystals occur inparallel to sub-parallel aggregates up to 5 mm across ina matrix of calcite and plagioclase feldspar. Crystals are pale bluish-grey with a greyish-white streak. Fluoro-sodic-ferropedrizite is brittle, has a Mohs hardness of ~6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.116 g cm−3. In plane-polarized light, it is pleochroic, X = pale purple-grey, Y = light grey, Z = colourless; X^ a = 71.2º (in β acute), Y || b, Z^c = 83.4º (in β obtuse). Fluoro-sodic-ferropedrizite is biaxial positive, α= 1.642(1), β= 1.644(1), g = 1.652(1); 2V(obs) = 68.0(3)º, 2V(calc) = 56.4º. Fluoro-sodic-ferropedrizite is monoclinic, space group C2/m, a = 9.3720(4) Å, b = 17.6312(8) Å, c = 5.2732(3) Å, β= 102.247(4)º, V = 851.5(2) Å3, Z = 2. The strongest ten X-ray diffraction lines in the powder patternare (d in Å,(I),(hkl)): 8.146,(10),(110); 2.686,(9),(151); 3.008,(8),(310); 4.430,(7),(021); 2.485,(6),(2̅02); 3.383,(4),(131); 2.876,(3),(1̅51, 3̅11); 2.199,(3),(3̅12); 4.030,(2),(111) and 3.795,(2),(1̅31). Analysis by a combination of electron microprobe and crystal-structure refinement gives SiO2 59.81, Al2O3 12.66, TiO2 0.09, FeO 10.32, MgO 5.56, MnO 0.73, ZnO 0.17, CaO 0.20, Na2O 2.81, Li2O 4.80, F 2.43, H2Ocalc 1.10, sum = 99.65 wt.%. The formula unit, calculated on the basis of 24(O,OH,F) is A(Na0.68)B(Li1.92Na0.05Ca0.03)C(Fe2+1.16Mg1.10Mn2+0.08Zn0.02Al1.97Ti0.01Li0.66)T(Si7.98Al0.02)O22W(F1.03OH0.97). Crystal-structure refinement shows Li to be completely ordered at the M(3) and M(4) sites. Fluoro-sodic-ferropedrizite, ideally ANaBLi2C(Fe2+2 Al2Li)TSi8O22WF2, is related to the theoretical end-member ‘sodic-pedrizite’, ANaBLi2C(Mg2Al2Li)TSi8O22W(OH)2, by the substitutions CFe2+ → CMg and WF → W(OH).

Carlfrancisite: Mn32+(Mn2+,Mg,Fe3+,Al)42(As3+O3)2(As5+O4)4[(Si,As5+)O4]6[(As5+,Si)O4]2(OH)42, a new arseno-silicate mineral from the Kombat mine, Otavi Valley, Namibia

Abstract Fluoro-aluminoleakeite, ideally ANaBNa2C(Mg2Al2Li)TSi8O22WF2, is a new mineral of the amphibole group from Norra Kärr, Sweden (IMA-CNMMNC 2009-012). It occurs ina proterozoic alkaline intrusion that mainly comprises a fine-grained schistose agpaitic nepheline-syenite (grennaite). Fluoro-aluminoleakeite occurs as isolated prismatic crystals 0.10-2 mm long in a syenitic matrix. Crystals are light greenish-blue with a greenish-blue streak. It is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.14 g cm−3. In plane-polarized light, it is pleochroic, X = pale green, Y = dark green, Z = pale green; X ^ a = 62.9° (in β obtuse), Y ∥ b. Fluoro-aluminoleakeite is biaxial negative, α = 1.632(1), β = 1.638(1), γ = 1.643(1); 2Vobs. = 98.0(4)°, 2Vcalc. = 95.5°. Fluoro-aluminoleakeite is monoclinic, space group C2/m, a = 9.7043(5) Å, b = 17.7341(8) Å, c = 5.2833(3) Å, β = 104.067(4)°, V = 882.0(2) Å3, Z = 2. The eight strongest X-ray diffraction lines in the powder-diffraction pattern are [d in Å, (I), (hkl)]: 2.687, (100), (3̅31, 151); 4.435, (80), (021, 040); 3.377, (80), (131); 2.527, (60), (2̅02); 8.342, (50), (110); 3.096, (40), (310); 2.259, (40), (1̅71, 3̅12) and 2.557, (30), (002, 061). Analysis, by a combination of electron microprobe and crystal-structure refinement, gives SiO2 58.61, Al2O3 7.06, TiO2 0.32, FeO 3.27, Fe2O3 6.05, MgO 8.61, MnO 0.73, ZnO 0.43, CaO 0.05, Na2O 9.90, K2O 2.43, Li2O 1.62, F 3.37, H2Ocalc. 0.50, sum 101.08 wt.%. The formula unit, calculated on the basis of 24 (O,OH,F,Cl) p.f.u. with (OH) + F = 2 a.p.f.u., is A(Na0.65K0.43)Σ=1.09B(Na1.99Ca0.01)Σ=2.00C(Mg1.77Fe2+0.38Mn0.09Zn0.04Fe3+0.63Al1.16Ti0.03Li0.90)Σ=5.00TSi8.00O22W(F1.47OH0.53)Σ=2.00. Crystal-structure analysis shows CLi to be completely ordered at the M(3) site, and provided reliable site populations. Fluoro-aluminoleakeite is related to the end-member leakeite,ANaBNa2C(Mg2Fe3+2Li)TSi8O22W(OH)2, by the substitutions CFe3+ → CAl and WF → W(OH).