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Celleriite, □(Mn22+Al)Al6(Si6O18)(BO3)3(OH)3(OH),$\square \,\left( \text{Mn}_{2}^{2+}\text{Al} \right)\text{A}{{\text{l}}_{6}}\left( \text{S}{{\text{i}}_{6}}{{\text{O}}_{18}} \right){{\left( \text{B}{{\text{O}}_{3}} \right)}_{3}}{{(\text{OH})}_{3}}(\text{OH}),$is a new mineral of the tourmaline supergroup. It was discovered in the Rosina pegmatite, San Piero in Campo, Elba Island, Italy (holotype specimen), and in the Pikárec pegmatite, western Moravia, Czech Republic (co-type specimen). Celleriite in hand specimen is violet to gray-blue (holotype) and dark brownish-green (co-type) with a vitreous luster, conchoidal fracture, and white streak. Celleriite has a Mohs hardness of ~7 and a calculated density of 3.13 and 3.14 g/cm3for holotype and its co-type, respectively. In plane-polarized light in thin section, celleriite is pleochroic (O = pale violet and E = light gray-blue in holotype; O = pale green and E = colorless in co-type) and uniaxial negative. Celleriite has trigonal symmetry: space group R3m, Z= 3, a= 15.9518(4) and 15.9332(3) Å, c= 7.1579(2) and 7.13086(15) Å, V= 1577.38(9) and 1567.76(6) Å3for holotype and co-type, respectively (data from single-crystal X‑ray diffraction). The crystal structure of the holotype specimen was refined to R1 = 2.89% using 1696 unique reflections collected with MoKα X‑ray intensity data. Structural, chemical, and spectroscopic analyses resulted in the formulas: x(□0.58Na0.42)∑1.00Y(Mn1.392+Fe0.162+Mg0.01Al1.14Fe0.013.0Li0.28T0.01)Σ3.00ZAl6[T(Si5.99Al0.01)Σ6.00O18](BO3)3(OH)3w[(OH)0.65F0.03O0.32]Σ1.00(forholotype)$\begin{align}& \,\,\,\,{{\,}^{\text{x}}}{{\left( {{\square }_{0.58}}\text{N}{{\text{a}}_{0.42}} \right)}_{\sum 1.00}}\text{Y}{{\left( \text{Mn}_{1.39}^{2+}\text{Fe}_{0.16}^{2+}\text{M}{{\text{g}}_{0.01}}\text{A}{{\text{l}}_{1.14}}\text{Fe}_{0.01}^{3.0}\text{L}{{\text{i}}_{0.28}}~{{\text{T}}_{0.01}} \right)}_{\Sigma 3.00}}^{\text{Z}}\text{A}{{\text{l}}_{6}}\left[ {{~}^{\text{T}}}{{\left( \text{S}{{\text{i}}_{5.99}}\text{A}{{\text{l}}_{0.01}} \right)}_{\Sigma 6.00}}{{\text{O}}_{18}} \right]{{\left( \text{B}{{\text{O}}_{3}} \right)}_{3}}{{(\text{OH})}_{3}} \\ & ^{\text{w}}{{\left[ {{(\text{OH})}_{0.65}}~{{\text{F}}_{0.03}}{{\text{O}}_{0.32}} \right]}_{\Sigma 1.00}}\,\text{(for}\,\text{holotype)} \\ \end{align}$andX(□0.51Na0.49)Σ1.00Y(Mn0.902+Fe0502+Al1.36Fe0043+Li0.17Zn0.04)Σ3.00ZAl6[T(Si5.75B0.25)Σ6.00O18](BO3)3(OH)3w[(OH)0.35F0.17O0.48]∑1.00(forco-type)$\begin{align}& \,\,\,\,\,{{\,}^{\text{X}}}{{\left( {{\square }_{0.51}}\text{N}{{\text{a}}_{0.49}} \right)}_{\Sigma 1.00}}^{\text{Y}}{{\left( \text{Mn}_{0.90}^{2+}\text{Fe}_{050}^{2+}\text{A}{{\text{l}}_{1.36}}\text{Fe}_{004}^{3+}\text{L}{{\text{i}}_{0.17}}\text{Z}{{\text{n}}_{0.04}} \right)}_{\Sigma 3.00}}^{\text{Z}}\text{A}{{\text{l}}_{6}}\left[ ^{\text{T}}{{\left( \text{S}{{\text{i}}_{5.75}}~{{\text{B}}_{0.25}} \right)}_{\Sigma 6.00}}{{\text{O}}_{18}} \right]{{\left( \text{B}{{\text{O}}_{3}} \right)}_{3}}{{(\text{OH})}_{3}} \\ & ^{\text{w}}{{\left[ {{(\text{OH})}_{0.35}}~{{\text{F}}_{0.17}}{{\text{O}}_{0.48}} \right]}_{\sum 1.00}}\text{(for}\,\text{co-type)} \\ \end{align}$

The system B2O3-Al2O3-SiO2(BAS) includes two ternary phases occurring naturally, boromullite, Al9BSi2O19, and boralsilite, Al16B6Si2O37, as well as synthetic compounds structurally related to mullite. The new mineral vránaite, a third naturally occurring anhydrous ternary BAS phase, is found with albite and K-feldspar as a breakdown product of spodumene in the elbaite-subtype Manjaka granitic pegmatite, Sahatany Valley, Madagascar. Boralsilite also occurs in this association, although separately from vránaite; both minerals form rare aggregates of subparallel prisms up to 100 μm long. Optically, vránaite is biaxial (–), nα= 1.607(1), nβ= 1.634(1), nγ= 1.637(1) (white light), 2Vx(calc) = 36.4°, X≈ c; Y≈ a; Z= b. An averaged analysis by EMP and LA-ICP-MS (Li, Be) gives (wt%) SiO220.24, B2O311.73, Al2O364.77, BeO 1.03, MnO 0.01, FeO 0.13, Li2O 1.40, Sum 99.31. Raman spectroscopy in the 3000–4000 cm−1region rules out the presence of significant OH or H2O. Vránaite is monoclinic, space group I2/m, a= 10.3832(12), b= 5.6682(7), c= 10.8228(12) Å, β = 90.106(11)°; V= 636.97(13) Å3, Z= 1. In the structure [R1= 0.0416 for 550 Fo> 4σFo], chains of AlO6octahedra run parallel to [010] and are cross-linked by Si2O7disilicate groups, BO3triangles, and clusters of AlO4and two AlO5polyhedra. Two Al positions with fivefold coordination, Al4 and Al5, are too close to one another to be occupied simultaneously; their refined site-occupancy factors are 54% and 20% occupancy, respectively. Al5 is fivefold-coordinated Al when the Al9 site and both O9 sites are occupied, a situation giving a reasonable structure model as it explains why occupancies of the Al5 and O9 sites are almost equal. Bond valence calculations for the Al4 site suggest Li is likely to be sited here, whereas Be is most probably at the Al5 site. One of the nine O sites is only 20% occupied; this O9 site completes the coordination of the Al5 site and is located at the fourth corner of what could be a partially occupied BO4tetrahedron, in which case the B site is shifted out of the plane of the BO3triangle. However, this shift remains an inference as we have no evidence for a split position of the B atom. If all sites were filled (Al4 and Al5 to 50%), the formula becomes Al16B4Si4O38, close to Li1.08Be0.47Fe0.02Al14.65B3.89Si3.88O36.62calculated from the analyses assuming cations sum to 24. The compatibility index based on the Gladstone-Dale relationship is 0.001 (“superior”). Assemblages with vránaite and boralsilite are inferred to represent initial reaction products of a residual liquid rich in Li, Be, Na, K, and B during a pressure and chemical quench, but at low H2O activities due to early melt contamination by carbonate in the host rocks. The two BAS phases are interpreted to have crystallized metastably in lieu of dumortierite in accordance with Ostwald Step Rule, possibly first as “boron mullite,” then as monoclinic phases. The presence of such metastable phases is suggestive that pegmatites crystallize, at least partially, by disequilibrium processes, with significant undercooling, and at high viscosities, which limit diffusion rates.

Primary black thick-prismatic Al-rich schorl to rare fluor-schorl (TurP1), locally overgrown by brownish-green Li-rich fluor-schorl to fluor-elbaite (TurP2) from the Kracovice pegmatite (mixed NYF+LCT signature), was partly replaced by secondary Li-rich fluor-schorl to fluor-elbaite (TurS) plus the assemblage REE-bearing epidote-group mineral + chamosite. Primary Al-rich schorl (TurP1) shows high and variable contents of Sc (33-364 ppm) and Y+REE (40-458 ppm) with steep, LREEenriched REE pattern. Overgrowing (TurP2) and replacing (TurS) Li-rich fluor-schorl to fluor-elbaite is typically depleted in Sc (21-60 ppm) and Y+REE (3-47 ppm) with well-developed tetrad effect in the first (La-Nd) and the second (Sm-Gd) tetrads. Scandium- and REE-rich black tourmaline (TurP1) crystallized earlier from the melt, whereas crystallization of primary Li-rich fluor-schorl to fluor-elbaite (TurP2) most likely took place during late magmatic to early hydrothermal conditions. Both the secondary Li-rich fluor-schorl to fluor-elbaite (TurS) and the unusual assemblage of REE-bearing epidotegroup mineral + chamosite are likely coeval products of subsolidus reactions of the magmatic Al-rich schorl (TurP1) with evolved REE-poor, Li,F-rich, alkaline pegmatite-derived fluids. Well-crystalline REE-bearing epidote-group mineral (Y+REE = 0.42-0.60 apfu) confirmed by Raman spectroscopy has a steep, LREE-rich chondrite-normalized REE pattern with significant negative Eu anomaly and shows variable and high contents of Sc (≤3.3 wt% Sc2O3) and Sn (≤1.0 wt% SnO2). Substitution ScAl-1and minor vacancy in the octahedral sites are suggested in the REE-bearing epidote-group mineral.

Garnet and other rock-forming minerals from A-type granite dikes in the Pre-Variscan Brno Batholith were analyzed to determine relative contributions of individual minerals to whole-rock Y and REE budget and to assess incorporation mechanisms of these elements in garnet. Minor to accessory garnet (<2 vol%) is the essential reservoir for Y+REE in the Hlína granite accounting ∼84% Y and 61% REE of the total whole-rock budget. Zircon is another important carrier of REE with ∼13% Y and ∼11% REE. At least ∼21% REE and 1% Y were probably hosted by Th- and U-rich monazite that has been completely altered to a mixture of secondary REE-bearing phases. The contribution of major rockforming minerals (quartz and feldspars) is low (∼1% Y; 10% LREE; ∼1% HREE) excluding Eu, which is hosted predominantly by feldspars (∼90%). Minor to accessory muscovite and magnetite incorporate ∼1% Y and ∼2% REE of the whole-rock budget. Magmatic garnet Sps41-46Alm28-44And0-13Grs6-12Prp0-1is Y- and HREE-rich (up 1.54 wt% Y; up ∼1 wt% ΣREE), and the Y+REE enter the garnet structure via the menzerite-(Y) substitution. The Y and REE show complex zoning patterns and represent sensitive indicator of garnet evolution, in contrast to a homogeneous distribution of major divalent cations. General outward decrease of Y+REE is a common feature due to the strong partitioning of Y+HREE in the garnet relative to the other phases. REE underwent significant fractionation during growth of early garnet I; the YbN/NdN ratio generally decreases from the core to rim of garnet I. Higher Mn and Al, lower Ca, and Y+REE contents, as well as higher YbN/NdNratio and more negative Eu anomaly in garnet II overgrowths indicate its crystallization from a more evolved melt. Application of zircon saturation geothermometry provides upper temperature limit of 734 ± 14 °C for the closed-system crystallization. Mineral equilibria reveal that crystallization started at QFM + 1.2, and preferential sequestration of Fe3+ into garnet and magnetite was responsible for progressively reducing conditions. Equilibrium between magnetite, garnet, quartz, and plagioclase, representing the final crystallization stage of the granitic magma, occurred at 658-663 °C and QFM 0 to + 0.8, hence at undercooling of ∼75 °C.

Mathesiusite, K5(UO2)4(SO4)4(VO5)(H2O)4, a new uranyl vanadate-sulfate mineral from Jáchymov, Western Bohemia, Czech Republic, occurs on fractures of gangue associated with adolfpateraite, schoepite, čejkaite, zippeite, gypsum, and a new unnamed K-UO2-SO4mineral. It is a secondary mineral formed during post-mining processes. Mathesiusite is tetragonal, space group P4/n, with the unit-cell dimensions a = 14.9704(10), c = 6.8170(5) Å, V = 1527.78(18) Å3, and Z = 2. Acicular aggregates of mathesiusite consist of prismatic crystals up to ~200 μm long and several micrometers thick. It is yellowish green with a greenish white streak and vitreous luster. The Mohs hardness is ~2. Mathesiusite is brittle with an uneven fracture and perfect cleavage on {110} and weaker on {001}. The calculated density based on the empirical formula is 4.02 g/cm3. Mathesiusite is colorless in fragments, uniaxial (-), with ω = 1.634(3) and ε = 1.597(3). Electron microprobe analyses (average of 7) provided: K2O 12.42, SO318.04, V2O54.30, UO361.46, H2O 3.90 (structure), total 100.12 (all in wt%). The empirical formula (based on 33 O atoms pfu) is: K4.87(U0.99O2)4(S1.04O4)4(V0.87O5)(H2O)4. The eight strongest powder X-ray diffraction lines are [dobsin Å (hkl) Irel]: 10.64 (110) 76, 7.486 (200) 9, 6.856 (001) 100, 6.237 (101) 85, 4.742 (310) 37, 3.749 (400) 27, 3.296 (401) 9, and 2.9409 (510) 17. The crystal structure of mathesiusite was solved from single-crystal X-ray diffraction data and refined to R1= 0.0520 for 795 reflections with I > 3σ(I). It contains topologically unique heteropolyhedral sheets based on [(UO2)4(SO4)4(VO5)]5-clusters. These clusters arise from linkages between corner-sharing quartets of uranyl pentagonal bipyramids, which define a square-shaped void at the center that is occupied by V5+cations. Each pair of uranyl pentagonal bipyramids shares two vertices of SO4tetrahedra. Each SO4shares a third vertex with another cluster to form the sheets. The K+cations are located between the sheets, together with a single H2O group. The corrugated sheets are stacked perpendicular to c. These heteropolyhedral sheets are similar to those in the structures of synthetic uranyl chromates. Raman spectral data are presented confirming the presence of UO22+, SO4, and molecular H2O.

Darrellhenryite, Na(LiAl2)Al6(BO3)3Si6O18(OH)3O, a new member of the tourmaline supergroup (related to the alkali-subgroup 4), is a new Li-bearing tourmaline species, which is closely related to elbaite through the substitution YAlW0.5O1YLiW-0.5(OH)-1. It occurs in a complex (Li-bearing) petalite-subtype pegmatite with common lepidolite, Li-bearing tourmalines, and amblygonite at Nová Ves near Ceský Krumlov, southern Bohemia, Moldanubian Zone, Czech Republic. This zoned pegmatite dike cross-cuts a serpentinite body enclosed in leucocratic granulites. Pink darrellhenryite forms columnar crystals (sometimes in parallel arrangement) up to 3 cm long and up 2 cm thick, associated with albite (var. cleavelandite), minor quartz, K-feldspar, petalite, rare polylithionite, and locally rare pollucite. The optical properties and the single-crystal structure study (R1 = 0.019) of darrellhenryite are consistent with trigonal symmetry, w = 1.636(2), e = 1.619(2), birefringence: 0.017, space group R3m, a = 15.809(2), c = 7.089(1) Å, V = 1534.4(4) Å3, and Z = 3. The chemical analysis, in combination with the results from the single-crystal structure refinement, gives the formula X(Na0.58Ca0.01?0.41)1.00Y(Li1.05Al1.95)3.00ZAl6(BO3)3T(Si6O18)V(OH)3W(O0.66F0.34)1.00, which can be simplified to an ideal formula of Na(LiAl2) Al6(BO3)3Si6O18(OH)3O. The strongest lines of the powder pattern [d in Å (I, hkl)] are 4.180 (39, 211), 3.952 (54, 220), 3.431 (73, 012), 2.925 (100, 122), 2.555 (90, 051), 2.326 (42, 511), 2.029 (42, 223), 2.021 (42, 152), 1.901 (50, 342), 1.643 (49, 603). The density is Dmeas= 3.03(3) g/cm3, Dcalc= 3.038 g/ cm3. Darrellhenryite is considered to have crystallized in Li- and B-rich but F-moderate environments in complex pegmatites; no influence of higher activity of O on the darrellhenryite formation is implied from its mineral assemblage. The name is for Darrell J. Henry, Professor of Geology at the Louisiana State University, Baton Rouge, U.S.A., an expert on the mineralogy, petrology, crystal chemistry, and nomenclature of tourmaline-supergroup minerals.

Abstract Oxy-schorl (IMA 2011-011), ideally Na(Fe22+Al)Al6Si6O18(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup, is described. In Zlatá Idka, Slovak Republic (type locality), fan-shaped aggregates of greenish black acicular crystals ranging up to 2 cm in size, forming aggregates up to 3.5 cm thick were found in extensively metasomatically altered metarhyolite pyroclastics with Qtz+Ab+Ms. In Pribyslavice, Czech Republic (co-type locality), abundant brownish black subhedral, columnar crystals of oxy-schorl, up to 1 cm in size, arranged in thin layers, or irregular clusters up to 5 cm in diameter, occur in a foliated muscovite-tourmaline orthogneiss associated with Kfs+Ab+Qtz+Ms+Bt+Grt. Oxy-schorl from both localities has a Mohs hardness of 7 with no observable cleavage and parting. The measured and calculated densities are 3.17(2) and 3.208 g/cm3 (Zlatá Idka) and 3.19(1) and 3.198 g/cm3(Pribyslavice), respectively. In plane-polarized light, oxy-schorl is pleochroic; O = green to bluish-green, E = pale yellowish to nearly colorless (Zlatá Idka) and O = dark grayish-green, E = pale brown (Pribyslavice), uniaxial negative, ? = 1.663(2), e = 1.641(2) (Zlatá Idka) and ? = 1.662(2), e = 1.637(2) (Pribyslavice). Oxy-schorl is trigonal, space group R3m, Z = 3, a = 15.916(3) Å, c = 7.107(1) Å, V = 1559.1(4) Å3(Zlatá Idka) and a = 15.985(1) Å, c = 7.154(1) Å, V = 1583.1(2) Å3(Pribyslavice). The composition (average of 5 electron microprobe analyses from Zlatá Idka and 5 from Pribyslavice) is (in wt%): SiO233.85 (34.57), TiO2<0.05 (0.72), Al2O339.08 (33.55), Fe2O3not determined (0.61), FeO 11.59 (13.07), MnO <0.06 (0.10), MgO 0.04 (0.74), CaO 0.30 (0.09), Na2O 1.67 (1.76), K2O <0.02 (0.03), F 0.26 (0.56), Cl 0.01 (<0.01), B2O3(calc.) 10.39 (10.11), H2O (from the crystal-structure refinement) 2.92 (2.72), sum 99.29 (98.41) for Zlatá Idka and Pribyslavice (in parentheses). A combination of EMPA, Mössbauer spectroscopy, and crystal-structure refinement yields empirical formulas (Na0.591Ca0.103?0.306)S1.000(Al1.885Fe2+1.108Mn0.005Ti0.002)S3.000(Al5.428Mg0.572)S6.000(Si5.506Al0.494)S6.000O18 (BO3)3(OH)3(O0.625OH0.236F0.136Cl0.003)S1.000for Zlatá Idka, and (Na0.586Ca0.017K0.006?0.391)S1.000(Fe2+1.879Mn0.015Al1.013Ti0.093)S3.00(Al5.732Mg0.190Fe3+0.078)S6.000(Si5.944Al0.056)S6.000O18(BO3)3(OH)3(O0.579F0.307OH0.115)S1000for Pribyslavice. Oxy-schorl is derived from schorl end-member by the AlOFe-1(OH)-1 substitution. The studied crystals of oxy-schorl represent two distinct ordering mechanisms: disorder of R2+and R3+cations in octahedral sites and all O ordered in the W site (Zlatá Idka), and R2+and R3+cations ordered in the Y and Z sites and O disordered in the V and W sites (Pribyslavice).

Sejkoraite-(Y), the triclinic (Y1.98Dy0.24)Σ2.22H+0.34[(UO2)8O88O7OH(SO4)4](OH)(H2O)26, is a new member of the zippeite group from the Červená vein, Jáchymov (Street Joachimsthal) ore district, Western Bohemia, Czech Republic. It grows on altered surface of relics of primary minerals: uraninite, chalcopyrite, and tennantite, and is associated with pseudojohannite, rabejacite, uranopilite, zippeite, and gypsum. Sejkoraite-(Y) forms crystalline aggregates consisting of yellow-orange to orange crystals, rarely up to 1 mm in diameter. The crystals have a strong vitreous luster and a pale yellow-to-yellow streak. The crystals are very brittle with perfect {100} cleavage and uneven fracture. The Mohs hardness is about 2. The mineral is not fluorescent either in short- or long-wavelength UV radiation. Sejkoraite-(Y) is yellow, with no visible pleochroism, biaxial negative with α′ = 1.62(2), β′ = 1.662(3), γ′ = 1.73(1), 2Vcalc= 79°. The empirical chemical formula (mean of 8 electron microprobe point analyses) was calculated on the basis of 12 (S + U) atoms: (Y1.49Dy0.17Gd0.11Er0.07Yb0.05Sm0.02)Σ1.90H+0.54[(UO2)8.19O7OH(SO4)3.81](H2O)26.00. Sejkoraite-(Y) is triclinic, space group P1̄, a = 14.0743(6), b = 17.4174(7), c = 17.7062(8) Å, α = 75.933(4), β = 128.001(5), γ = 74.419(4)°, V = 2777.00(19) Å3, Z = 2, Dcalc= 4.04 g/cm3. The seven strongest reflections in the X-ray powder diffraction pattern are [dobs in Å (I) (hkl)]: 9.28 (100) (100), 4.64 (39) (200), 3.631 (6) (1̄42), 3.451 (13) (1̄44), 3.385 (10) (2̅4̅2), 3.292 (9) (044), 3.904(7) (300), 2.984 (10) (1̄4̅2). The crystal structure of sejkoraite-(Y) has been solved by the charge flipping method from single-crystal X-ray diffraction data and refined to Robs= 0.060 with GOFobs= 2.38, based on 6511 observed reflections. The crystal structure consists of uranyl sulfate sheets of zippeite anion topology, which alternate with an interlayer containing Y3+(H2O)n polyhedra and uncoordinated H2O groups. Two yttrium atoms are linked to the sheet directly via uranyl oxygen atom, and the remaining one is bonded by hydrogen bonds only. In the Raman and infrared spectrum of sejkoraite-(Y) there are dominating stretching vibrations of SO4tetrahedra (-1200-1100 cm-1), UO22+stretching vibrations (-900-800 cm-1), and O-H stretching (-3500-3200 cm-1) and H-O-H bending modes (-1640 cm-1). The new mineral is named to honor Jiří Sejkora, a Czech mineralogist of the National Museum in Prague.

A nomenclature for tourmaline-supergroup minerals is based on chemical systematics using the generalized tourmaline structural formula: XY3Z6(T6O18)(BO3)3V3W, where the most common ions (or vacancy) at each site are X = Na1+, Ca2+, K1+, and vacancy; Y = Fe2+, Mg2+, Mn2+, Al3+, Li1+, Fe3+, and Cr3+; Z = Al3+, Fe3+, Mg2+, and Cr3+; T = Si4+, Al3+, and B3+; B = B3+; V = OH1-and O2-; and W = OH1-, F1-, and O2-. Most compositional variability occurs at the X, Y, Z, W, and V sites. Tourmaline species are defined in accordance with the dominant-valency rule such that in a relevant site the dominant ion of the dominant valence state is used for the basis of nomenclature. Tourmaline can be divided into several groups and subgroups. The primary groups are based on occupancy of the X site, which yields alkali, calcic, or X-vacant groups. Because each of these groups involves cations (or vacancy) with a different charge, coupled substitutions are required to relate the compositions of the groups. Within each group, there are several subgroups related by heterovalent coupled substitutions. If there is more than one tourmaline species within a subgroup, they are related by homovalent substitutions. Additionally, the following considerations are made. (1) In tourmaline-supergroup minerals dominated by either OH1-or F1-at the W site, the OH1--dominant species is considered the reference root composition for that root name: e.g., dravite. (2) For a tourmaline composition that has most of the chemical characteristics of a root composition, but is dominated by other cations or anions at one or more sites, the mineral species is designated by the root name plus prefix modifiers, e.g., fluor-dravite. (3) If there are multiple prefixes, they should be arranged in the order occurring in the structural formula, e.g., “potassium-fluor-dravite.”

A mineral assemblage involving grandidierite, ominelite, boralsilite, werdingite, dumortierite (locally Sb,Ti-rich), tourmaline, and corundum, along with the matrix minerals K-feldspar, quartz, and plagioclase, was found in a veinlet cutting leucocratic granulite at Horní Bory, Bory Granulite Massif, Moldanubian Zone of the Bohemian Massif. Zoned crystals of primary grandidierite to ominelite enclosed in quartz are locally overgrown by prismatic crystals of boralsilite and Fe-rich werdingite. Boralsilite also occurs as separate cross-shaped plumose aggregates with Fe-rich werdingite in quartz. Grandidierite is commonly rimmed by a narrow zone of secondary tourmaline or is partially replaced by the assemblage tourmaline + corundum ± hercynite. Grandidierite (XFe= 0.34-0.71) exhibits dominant FeMg-1substitution and elevated contents of Li (120-1890 ppm). Boralsilite formula ranges from Al15.97B6.20Si1.80O37to Al15.65B5.29Si2.71O37and the formula of werdingite ranges from (Fe,Mg)1.44Al14.61B4.00Si3.80O37to (Fe,Mg)1.22Al14.86B4.25Si3.55O37. Dumortierite and Sb,Ti-rich dumortierite occur as zoned crystals with zones poor in minor elements (≤0.12 apfu Fe+Mg) and zones enriched in Sb (≤0.46 apfu) and Ti (≤0.25 apfu). Secondary tourmaline (XFe= 0.44-0.75) of the schorlmagnesiofotite- foitite-olenite solid solution occurs as a replacement product of grandidierite, rarely boralsilite. Other accessory minerals in the veinlet include monazite-(Ce), ilmenite, rutile, ferberite, srilankite, löllingite, arsenopyrite, and apatite. Formation of the borosilicate-bearing veinlet post-dates the development of foliation in the host granulite and is related to the decompressional process. The assemblage most probably originated from a H2O-poor system at T ~ 750 °C and P ~ 6-8 kbar. Textural relations as well as geological position of the borosilicate veinlet suggest that it represents the earliest intrusion related to pegmatites in the Bory Granulite Massif. Younger granitic pegmatites in the area are characterized by high contents of B, Al, P, Fe, and minor concentrations of W, Ti, Zr, Sc, and Sb. All pegmatite types probably formed within a short time period of ~5 Ma.

The mode of occurrence and chemical composition of five types of micas with Rb- or Cs-dominant populations of interlayer cations, collected from the Red Cross Lake rare-element pegmatites in north-central Manitoba, are described here. All five micas are candidates for new mineral species but crystal-structural data and Li contents could not be determined to date because of extremely small particle size, restricted to the margins of strongly zoned microcrystals. Based on electron-microprobe analyses, on Li contents estimated from Li/F (at.) = 1.0, and on bulk analysis of ferromagnesian micas for FeO and Fe2O3, the micas correspond to Rb- and Cs-dominant polylithionite (with representative interlayer populations of Rb0.82K0.12Cs0.07and Cs0.74Rb0.12K0.08apfu, respectively), Rb and Cs-dominant magnesian annite (Rb45K0.37Cs0.20and Cs0.67Rb0.20K0.12apfu, respectively), and Cs-dominant ferroan phlogopite (Cs0.92Rb0.04K0.02apfu).

The mode of occurrence and chemical composition of five types of micas with Rb- or Cs-dominant populations of interlayer cations, collected from the Red Cross Lake rare-element pegmatites in north-central Manitoba, are described here. All five micas are candidates for new mineral species but crystal-structural data and Li contents could not be determined to date because of extremely small particle size, restricted to the margins of strongly zoned microcrystals. Based on electron-microprobe analyses, on Li contents estimated from Li/F (at.) = 1.0, and on bulk analysis of ferromagnesian micas for FeO and Fe2O3, the micas correspond to Rb- and Cs-dominant polylithionite (with representative interlayer populations of Rb0.82K0.12Cs0.07and Cs0.74Rb0.12K0.08apfu, respectively), Rb and Cs-dominant magnesian annite (Rb45K0.37Cs0.20and Cs0.67Rb0.20K0.12apfu, respectively), and Cs-dominant ferroan phlogopite (Cs0.92Rb0.04K0.02apfu).

Rossmanite is a new tourmaline species from near Rožná, western Moravia, Czech Republic. It forms pale pink columnar crystals about 25 mm long and 5 mm thick, elongaten along c with striations parallel to c on the prism faces. It is brittle, H= 7, Dmeas= 3.00 g/cm3, Dcalc= 3.06 g/cm3. In plane-polarized light, it is colorless. Rossmanite is uniaxial negative, to = 1.645(1), e = 1.624(1), trigonal, space group R3m, in the hexagonal setting a = 15.770(2), c = 7.085(1) Å, V = 1525.8(4) Å3, Z= 3. The strongest six X-ray diffraction lines in the powder pattern are at d = 3.950 Å with I = 100% for (hkl) = (220); 2.552 Å, 93%, (051); 1.898 Å, 72%, (342); 4.181 Å, 58%, (211); 2.924 Å, 56%, (122); and 3.434 Å, 53%, (012). Analysis by a combination of electron microprobe, SIMS, H-line extraction, and crystal-structure refinement gave SiO238.10 wt%, Al2O344.60, Na2O 1.43, Li2O = 1.13, B2O3= 10.88, H2O = 3.70, F = 0.20, O ≡ F 0.08, sum = 99.96 wt%, Fe, Mg, Ca, Mn, Ti, F, K not detected. The formula unit (31 anions) is x(⃞57Na0.43)Y(Li0.71Al2.17)zAl6(Si5.92O18) (B2.92O9)(OH)3.83F0.10O0.07, with the ideal end-member formula ⃞(LiAl2)Al6(Si6O18)(BO3)3(OH)4; thus rossmanite can be derived from elbaite [Na(Al1.5Li1.5)(Si6O18)(BO3)3(OH)4] by the substitution x⃞2+ YAl → xNa2+ YLi, where ⃞ = vacancy. The crystal structure of rossmanite was refined to an R index of 1.7% using 1094 observed (5σ) reflections collected with MoKα X-radiation from a single crystal. The structure refinement confirmed the low occupancy of the X site and the presence of Li at the Y site. There is considerable positional disorder at the O1 and O2 sites induced by the local variations in bond-valence distribution associated with ⃞-Na disorder at X and Li-Al disorder at Y.