Heinz-Jürgen Bernhardt

Reexamination of olenite from the type locality: detection of boron in tetrahedral coordination

Recent discoveries have demonstrated that some synthetic and natural olenite tourmalines contain less than the putative Si 6.00 p.f.u. , with the deficiencies in the tetrahedral sites being filled by excess boron (above B 3.00 p.f.u. ), existing as [4] B. Conversely, examination of the original study on natural olenite showed that B was assumed to be 3.00 and Si = 6.00 p.f.u. , and thus it has not been determined whether [4] B exists in the type material. For this reason, a crystal of olenite from the type locality was obtained and submitted for chemical and structural analysis. Chemical analysis by electron microprobe and secondary-ion mass spectrometry showed B = 3.37 p.f.u. in the core of the crystal, concomitant with the value of [4] Si = 5.47 p.f.u. ; the deficiency (from 6.0) in Si is relieved by the [4] B above B 3.00 p.f.u. with the remaining tetrahedral sites filled by [4] Al. The amount of [4] B calculated from chemical data was confirmed by site-refinement by single-crystal diffractometry, which yielded [4] B = 0.44 p.f.u. The optimized formula of the crystal, calculated using chemical and structural data, is (Na 0.541 Ca 0.023 □ 0.436 ) (Al 0.691 Li 0.210 Mn 0.029 Fe 0.014 □ 0.0563 A1 6 [Si 0.909 B 0.067 A1 0.024 ] 6 O 18 (BO 3 )3 (OH 3.832 F 0.161 O 0.006 Cl 0.001 ). The results of a complete chemical and structural characterization of an olenite crystal from the type locality in the Olenii Range, Kola Peninsula, Russia has important implications for future studies of the crystal chemistry of tourmaline group minerals, in particular that boron concentrations in excess of the usual 3 B p.f.u. may be common in tourmalines that have relatively high Al contents (above 7.0 p.f.u. ).

Complete solid solution between magnesian schorl and lithian excess-boron olenite in a pegmatite from the Koralpe (eastern Alps, Austria)

At the margins of a plagioclase-quartz pegmatite near Stoffhutte (Koralpe, Austroalpine realm, Austrian Alps), a new solid solution series within the tourmaline group (XY 3 Z 6 [T 6 O 18 ](BO 3 ) 3 V 3 W) has been found, namely between magnesian schorl and lithian excess-boron olenite. At the pegmatite contact with mylonitic garnet-biotite schists, a tourmalinite band developed. Massive tourmaline cores are Mg-rich schorl with normal boron contents of 3.0 cations per formula unit that most likely formed by a reaction of melt with garnet. Within the pegmatite, only olenitic crystals were found. Within a transition zone, the Mg-rich schorl crystals become zoned and develop olenitic rims of increasing size, most likely formed from a fluid via the reaction plagioclase ({+} H_{2}O {+} B_{2}O_{3} = olenite {+} quartz) . The major compositional changes are decreasing Fe, Mg and Si contents and X Mg values as well as increasing B, Al and Li contents. Over a distance of less than five centimetres, tourmaline composition determined by secondary ion microprobe (B, Li, Be, H) and electron microprobe (remaining elements, total Fe as Fe 2+ ) varies continuously from ((Na_{0.90}Ca_{0.11})(Fe_{1.61}Mg_{1.10}Mn_{0.01}Ti_{0.11}Zn_{0.01}Li_{0.01}Al_{0.10}{square}_{0.05})Al_{6.00}[Si_{6.01}O_{18}] (B_{2.99}O_{9})(OH_{3.02}F_{0.23}O_{0.75}) to (Na_{0.42}Ca_{0.31}{square}_{0.27})(Fe_{0.14}Mg_{0.03}Mn_{0.01}Ti_{0.06}Li_{0.33}Be_{0.01}Al_{2.49})Al_{6}[Si_{4.91}Al_{0.21}B_{0.88}O_{18}](B_{3.00}O_{9})OH_{3.38}F_{0.07})) . In contrast to the proton-deficient ideal olenite, the olenitic tourmaline from Stoffhutte contains 3.0–3.4 hydrogens per formula. The main substitutions are most likely (^{[Y]}Al^{3{+}} {+} ^{[T]}B^{3{+}} = ^{[T]}Si^{4{+}} {+} ^{[Y]}(Mg, Fe)^{2{+}}) , which is a modified Tschermaks9 substitution, (^{[Y]}Al^{3{+}} {+} ^{[Y]}Li^{{+}} = 2 ^{[Y]}(Mg, Fe)^{2{+}}) , (^{[X]}Ca^{2{+}} {+} ^{[X]}{square} = 2 ^{[X]}Na^{{+}}, ^{[Y]}Al^{3{+}} {+} ^{[X]}{square} = ^{[X]}Na^{{+}} {+} ^{[Y]}(Mg, Fe)^{2{+}} and ^{[Y]}Fe^{2{+}} = ^{[Y]}Mg^{2{+}}) . Coexisting muscovite and feldspar have considerable B (0.42–0.55 wt% and 71–134 ppm, respectively), Be (49–140 ppm and 79–169 ppm, respectively) and Li contents (6–9 ppm and 9–126 ppm, respectively). The apparent partition coefficient for total B between tourmaline and muscovite (D B = c tur / c ms ) varies between 6.5 and 16.8, but the values for tetrahedrally coordinated B (D B(T) ) range from 0 to 13.0.

Kapellasite, Cu3Zn(OH)6Cl2, a new mineral from Lavrion, Greece, and its crystal structure

Abstract Kapellasite, Cu3Zn(OH)6Cl2, is a new secondary mineral from the Sounion No. 19 mine, Kamariza, Lavrion, Greece. It is a polymorph of herbertsmithite. Kapellasite forms crusts and small aggregates up to 0.5 mm, composed of bladed or needle-like indistinct crystals up to 0.2 mm long. The colour is green-blue, the streak is light green-blue. There is a good cleavage parallel to {0001}. Kapellasite is uniaxial negative, ω = 1.80(1), Ɛ = 1.76(1); pleochroism is distinct, with E = pale green, O = green- blue. Dmeas = 3.55(10) g/cm3; Dcalc. = 3.62 g/cm3. Electron microprobe analyses of the type material gave CuO 58.86, ZnO 13.92, NiO 0.03, CoO 0.03, Fe2O3 0.04, Cl 16.70, H2O (calc.) 12.22, total 101.80, less O = Cl 3.77, total 98.03 wt.%. The empirical formula is (Cu3.24Zn0.75)∑3.99(OH)5.94Cl2.06, based on 8 anions. The five strongest XRD lines are [d in Å (I/I0, hkl)] 5.730 (100, 001), 2.865 (11, 002), 2.730 (4, 200), 2.464 (9, 021/201), 1.976 (5, 022/202). Kapellasite is trigonal, space group P3̅m1, unit-cell parameters (from single-crystal data) a = 6.300(1), c = 5.733(1) Å , V = 197.06(6) Å3, Z = 1. The crystal structure of kapellasite is based on brucite-like sheets parallel to (0001), built from edge-sharing distorted M(OH,Cl)6 (M = Cu, Zn) octahedra. The sheets stack directly on each other (…AAA…stacking). Bonding between adjacent sheets is only due to weak hydrogen and O…Cl bonds. The name is in honour of Christo Kapellas (1938−2004), collector and mineral dealer from Kamariza, Lavrion, Greece.

Mn-rich fluorapatite from Austria: Crystal structure, chemical analysis, and spectroscopic investigations

Abstract The crystal structure of a pale blue transparent Mn-rich fluorapatite (MnO: 9.79 wt%) with the optimized formula ∼(Ca8.56Mn2+1.41Fe2+0.01)P6O24F2.00 and space group P63/m, a = 9.3429(3), c = 6.8110(2) Å, Z = 2 has been refined to R = 2.05% for 609 unique reflections (MoKα). The Mn in the Eibenstein an der Thaya, Austria apatite is strongly ordered at the Ca1 site: Ca1: Ca0.72(1)Mn0.28, Ca2:Ca0.96(1)Mn0.04. There is a linear variation in as a function of Mn content (r2 = 1.00). The dominant band in the optical absorption spectrum of fluorapatite from Eibenstein is in the 640 nm region with E || c > E ⊥ c. The 640 nm band is attributed to Mn5+ at the P site by analogy with previous studies. This interpretation is consistent with studies of well-characterized synthetic materials of the apatite structure that contain Mn5+. Because Mn5+ has intense absorption in the visible region of the spectrum, if a small proportion of the total Mn is Mn5+ at the P site, that substituent dominates the spectrum and the color of the mineral. To determine if the pale blue color is due to radiation effects, a fragment of the fluorapatite crystal was heated at 400° C for 1 hour, and the change in color was slight. All of these observations are consistent with the origin of color from Mn5+. Assuming that all the intensity of the 640 nm (E || c) absorption is from Mn5+, the concentration of Mn5+ in this fluorapatite sample was calculated as 2.6% of the total manganese content (∼P5.96Mn5+0.04). The calibration was estimated from the spectrum of the related compound Sr5(P0.99Mn5+0.01)3Cl. The weak band at about 404 nm in the E || c spectrum may be the corresponding band for Mn2+ in octahedral coordination.

Schneebergite and nickelschneebergite from Schneeberg, Saxony, Germany: the first Bi-bearing members of the tsumcorite group

Schneebergite and nickelschneebergite are new members of the tsumcorite group; they represent the bismuth analogues of cobaltlotharmeyerite and nickellotharmeyerite. The two minerals were discovered on samples from the former mining area “Am Roten Berg”, Schneeberg, Saxony, Germany; associated minerals are scorodite, barium-pharmacosiderite, ferrilotharmeyerite (cobaltoan, bismuthian), preisingerite, and waylandite. Schneebergite and nickelschneebergite are very similar in appearance; they form crystal aggregates up to 1 mm and small tabular crystals (≤ 0.5 mm), elongated parallel to [010]. The colour is brown to beige (depending on the iron content), the streak is pale brown; Vickers hardness is VHN 15 = 250 kg/mm 2 corresponding to a Mohs9 hardness of 4 to 4 1/2. Crystallographic forms are {201} (dominant), {001}, {101}, {101}, {102}, {111}. The optical orientation is Y parallel to [010], X ≈ [001], pleochroism is weak to distinct (depending on the iron content) with X = Z = pale yellow and Y = brown (for both minerals). Schneebergite is biaxial positive, 2V = 85(5)°, n x = 1.93(calc.), n y = 1.95(1), and n z = 1.98(2); nickelschneebergite is biaxial negative, 2V = 77(5)°, n x = 1.92(calc.), n y = 1.95(1), and n z = 1.97(2). Empirical formulas calculated from electron microprobe analyses and based on 10 oxygen atoms are (Bi 0.74 Ca 0.29 ) Σ1.03 (Co 1.06 Ni 0.75 Fe 0.22 ) Σ2.03 [(AsO 4 )1.99(SO 4 ) 0.01 ] Σ2.00 [(OH) 1.09 (H 2 O) 0.91 ] Σ2.00 for schneebergite, and (Bi 0.73 Ca 0.28 Pb 0.01 ) Σ1.02 (Ni 1.18 Co 0.64 Fe 0.16 ) Σ1.98 (AsO 4 ) 1.99 [(H 2 O) 1.10 (OH) 0.93 ] Σ2.03 for nickelschneebergite; the ideal formulas are BiCo 2 (AsO 4 ) 2 [(H 2 O)(OH)] and BiNi 2 (AsO 4 ) 2 [(H 2 O)(OH)], respectively. There is a probably complete solid solution involving schneebergite, nickelschneebergite, cobaltlotharmeyerite, and nickellotharmeyerite. Schneebergite/nickelschneebergite are monoclinic, space group C 2/ m , with a = 9.005(1)/8.995(1), b = 6.211(1)/6.207(1), c = 7.440(1)/7.462(1) A, β = 115.19(1)/115.00(1)°, V = 376.5(1)/377.6(1) A 3 , Z = 2, D calc = 5.28/5.23 g/cm 3 . Structure investigations for schneebergite ( R 1 = 0.038) and nickelschneebergite ( R 1 = 0.044) based on single-crystal X-ray data confirmed isotypy with the tsumcorite-type structure.

On the symmetry of tsumcorite group minerals based on the new species rappoldite and zincgartrellite

Abstract Rappoldite, the Co-analogue of helmutwinklerite, and zincgartrellite, the Zn-dominant analogue of gartrellite, are two new members of the tsumcorite group. Both minerals are triclinic, their structures are closely related to the parent structure, i.e. the ‘tsumcorite type’ (C2/m, Z = 2). The lower symmetry is caused by two different crystal-chemical requirements. Order phenomena of the hydrogen bonds cause the ‘helmutwinklerite type’ (P1̅, Z = 4), ordering of Cu2+ and Fe3+ is responsible for the ‘gartrellite type’ (P1̅, Z = 1). Rappoldite was found on samples from the Rappold mine near Schneeberg, Saxony, Germany. The new species forms red to red-brown prismatic and tabular crystals up to 1 mm long. Dcalc. = 5.28 g/cm3. 2Vz = 85(5)°, nx = 1.85 (calc.), ny = 1.87(2) and nz = 1.90(2); dispersion is distinct with r > v; orientation is Y ~|| [1̅20] and X ~ || c. The empirical formula derived from electron microprobe analyses is (Pb1.01Ca0.01)Σ1.02(Co0.99Ni0.62Zn0.35Fe0.02)Σ1.98[(AsO4)1.99(SO4) Pb(Co,Ni)2(AsO4)2.2H2O. Single-crystal X-ray studies showed average C2/m symmetry. Weak superstructure reflections are responsible for triclinic symmetry and enlarged cell metrics (refined from powder data): a = 11.190(2) Å, b = 10.548(2) Å, c = 7.593(1) Å, α = 100.38(1)°, β = 109.59(2)°, γ = 98.96(1)°, V = 807.6 Å3, Z = 4. The superstructure results from the hydrogen-bond scheme, but faint streaks indicate some disorder. All investigated rappoldite crystals are twinned by reflection on (23̅0) which corresponds to the mirror plane of the average C2/m cell. Helmutwinklerite is isotypic with rappoldite and probably also with pure thometzekite; sulphatian thometzekite is monoclinic. Zincgartrellite forms green-yellow rosette-like aggregates on samples from the Tsumeb mine, Namibia. The Dcalc. = 5.30 g/cm3. 2Vx = 87(5)°, nx = 1.91(2), ny = 1.94 (calc.) and nz = 1.97(2). Electron-microprobe analyses and Mössbauer data yielded the empirical formula (Pb0.97Ca0.04)Σ1.01(Zn0.91sCu0.51Fe0.59Al0.03)Σ2.04[(AsO4)1.96(SO4)0.01]Σ1.97[(OH)0.81(H2O)1.31]Σ2.12 or Pb(Zn,Fe,Cu)2(AsO4)2(H2O,OH)2. The structural formula is Pb(ZnxFe11-x)(ZnxCu1-x)(AsO4)2(OH)1-x (H2O)1+x with 0.4 < x < 0.8. Gartrellite is defined by x < 0.4. Helmutwinklerite has x near to 1 and is defined by a cell with fourfold volume. Single-crystal X-ray studies of zincgartrellite proved space group P1̄ caused by ordering of Fe3+ and Cu at one atomic site. Cell parameters (refined from powder data): a = 5.550(1) Å, b = 5.620(1) Å, c = 7.621(1) Å, α = 68.59(1), β = 69.17(1), γ = 69.51(1)°, V = 200.1 Å3, Z = 1.

Brendelite, (Bi,Pb)2Fe3+,2+O2(OH)(PO4), a new mineral from Schneeberg, Germany: Description and crystal structure

SummaryBrendelite was found on specimens from the dumps of the Güldener Falk mine near Schneeberg, Saxony, Germany. The new mineral shows monoclinic holohedral symmetry and forms idiomorphic crystals (≤0.3 mm) and crystal aggregates (≤3 mm) which are frequently grown on crusts of eulytite; associated minerals are bismutite and bismutoferrite. The crystals of brendelite are tabular onn

Schlegelite, Bi7O4(MoO4)2(AsO4)3, a new mineral from Schneeberg, Saxony, Germany

{ bar 201}