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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)$\begin{align}& \,\,\,\,\,{{\,}^{\text{X}}}{{\left( {{\square }_{0.51}}\text{N}{{\text{a}}_{0.49}} \right)}_{\Sigma 1.00}}^{\text{Y}}{{\left( \text{Mn}_{0.90}^{2+}\text{Fe}_{050}^{2+}\text{A}{{\text{l}}_{1.36}}\text{Fe}_{004}^{3+}\text{L}{{\text{i}}_{0.17}}\text{Z}{{\text{n}}_{0.04}} \right)}_{\Sigma 3.00}}^{\text{Z}}\text{A}{{\text{l}}_{6}}\left[ ^{\text{T}}{{\left( \text{S}{{\text{i}}_{5.75}}~{{\text{B}}_{0.25}} \right)}_{\Sigma 6.00}}{{\text{O}}_{18}} \right]{{\left( \text{B}{{\text{O}}_{3}} \right)}_{3}}{{(\text{OH})}_{3}} \\ & ^{\text{w}}{{\left[ {{(\text{OH})}_{0.35}}~{{\text{F}}_{0.17}}{{\text{O}}_{0.48}} \right]}_{\sum 1.00}}\text{(for}\,\text{co-type)} \\ \end{align}$

Magnesio-lucchesiite, ideally CaMg3Al6(Si6O18)(BO3)3(OH)3O, is a new mineral species of the tourmaline supergroup. The holotype material was discovered within a lamprophyre dike that cross-cuts tourmaline-rich metapelites within the exocontact of the O’Grady Batholith, Northwest Territories (Canada). Two additional samples were found at San Piero in Campo, Elba Island, Tuscany (Italy) in hydrothermal veins embedded in meta- serpentinites within the contact aureole of the Monte Capanne intrusion. The studied crystals of magnesio-lucchesiite are black in a hand sample with vitreous luster, conchoidal fracture, an estimated hardness of 7–8, and a calculated density of 3.168 (Canada) and 3.175 g/cm3(Italy). In plane-polarized light, magnesio-lucchesiite is pleochroic (O = dark brown, E = colorless) and uniaxial (–); its refractive index values are nω= 1.668(3) and nε= 1.644(3) (Canada), and nω= 1.665(5) and nε= 1.645(5) (Italy). Magnesio-lucchesiite is trigonal, space group R3m, Z= 3, with a= 15.9910(3) Å, c= 7.2224(2) Å, V= 1599.42(7) Å3(Canada) and with a= 15.9270(10) Å, c= 7.1270(5) Å, V= 1565.7(2) Å3(Italy, sample 1). The crystal structure of magnesio-lucchesiite was refined to R1= 3.06% using 2953 reflections with Fo> 4σ(Fo) (Canadian sample; 1.96% / 1225 for the Italian sample) The Canadian (holotype) sample has the ordered empirical formula X(Ca0.60Na0.39K0.01)Σ1.00YMg2.02Fe0.622+Fe0.093+Ti0.25V0.01Cr0.01Σ3.00zAl5.31Fe0.693+Σ6.00TSi5.98Al0.02Σ6.00O18BO33v(OH)2.59O0.41Σ3.00${ }^{\mathrm{Y}}\left(\mathrm{Mg}_{2.02} \mathrm{Fe}_{0.62}^{2+} \mathrm{Fe}_{0.09}^{3+} \mathrm{Ti}_{0.25} \mathrm{~V}_{0.01} \mathrm{Cr}_{0.01}\right)_{\Sigma 3.00} \mathrm{z}\left(\mathrm{Al}_{5.31} \mathrm{Fe}_{0.69}^{3+}\right)_{\Sigma 6.00}\left[{ }^{\mathrm{T}}\left(\mathrm{S} \mathrm{i}_{5.98} \mathrm{Al}_{0.02}\right)_{\Sigma 6.00} \mathrm{O}_{18}\right]\left(\mathrm{BO}_{3}\right)_{3}{ }^{\mathrm{v}}\left[(\mathrm{OH})_{2.59} \mathrm{O}_{0.41}\right]_{\Sigma 3.00}$W(O0.78F0.22)Σ1.00. The Italian (co-type) material shows a wider chemical variability, with two different samples from the same locality having ordered chemical formulas: xCa0.88Na0.12Σ1.00YMg1.45Fe0.402+Al0.79Fe0.363+Σ3.00${ }^{\mathrm{x}}\left(\mathrm{Ca}_{0.88} \mathrm{Na}_{0.12}\right)_{\Sigma 1.00} \mathrm{Y}\left(\mathrm{Mg}_{1.45} \mathrm{Fe}_{0.40}^{2+} \mathrm{Al}_{0.79} \mathrm{Fe}_{0.36}^{3+}\right)_{\Sigma 3.00}$ZAl6[T(Si5.05Al0.95)Σ6.00O18](BO3)3V[(OH)2.90O0.10]Σ3.00W(O0.98F0.02)Σ1.00(sample 1) and X(Ca0.71Na0.21◻0.08)Σ1.00YMg2.49Fe0.412+Ti0.10Σ3.00ZAl5.44Fe0.463+Mg0.09V0.01Σ6.00TSi5.87Al0.13Σ6.00O18BO33V(OH)3WO0.61(OH)0.39Σ1.00${ }^{\mathrm{Y}}\left(\mathrm{Mg}_{2.49} \mathrm{Fe}_{0.41}^{2+} \mathrm{Ti}_{0.10}\right)_{\Sigma 3.00}^{\mathrm{Z}}\left(\mathrm{Al}_{5.44} \mathrm{Fe}_{0.46}^{3+} \mathrm{Mg}_{0.09} \mathrm{~V}_{0.01}\right)_{\Sigma 6.00}\left[{ }^{\mathrm{T}}\left(\mathrm{Si}_{5.87} \mathrm{Al}_{0.13}\right)_{\Sigma 6.00} \mathrm{O}_{18}\right]\left(\mathrm{BO}_{3}\right)_{3}{ }^{\mathrm{V}}(\mathrm{OH})_{3}{ }^{\mathrm{W}}\left[\mathrm{O}_{0.61}(\mathrm{OH})_{0.39}\right]_{\Sigma 1.00}$(sample 2). Magnesio-lucchesiite is an oxy-species belonging to the calcic group of the tourmaline supergroup. It is related to lucchesiite by the homovalent substitution YFe ↔ YMg, and to feruvite by the homovalent and heterovalent substitutions YFe ↔ YMg and ZAl3++ WO2–↔ ZMg2++ W(OH)1–. The new mineral was approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA 2019-025). Occurrences of magnesio-lucchesiite show that its presence is not restricted to replacement of mafic minerals only; it may also form in metacarbonate rocks by fluctuations of F and Al during crystallization of common uvitic tourmaline. High miscibility with other tourmaline end-members indicates the large petrogenetic potential of magnesio-lucchesiite in Mg,Al-rich calc-silicate rocks, as well as contact-metamorphic and metasomatic rocks.

Sakhaite, ca. Ca48Mg16(BO3)32(CO3)16(HCl,H2O)2, is a rare rock-forming borate-carbonate mineral typically occurring in high-temperature, low-pressure calcareous skarns. It forms a complete solid solution with harkerite, ca. Ca48Mg16[AlSi4(O,OH)16]4(BO3)16(CO3)16(HCl,H2O)2. The solid solution can be described with the general formula Ca48(Mg,Fe,Mn)16(CO3)16[AlaSi5−a(O,OH)16]y(BO3)32−4y(HCl,H2O)n$$\begin{array} {} {\rm{C}}{{\rm{a}}_{48}}{({\rm{Mg}},{\rm{Fe}},{\rm{Mn}})_{16}}{({\rm{C}}{{\rm{O}}_3})_{16}}{[{\rm{A}}{{\rm{l}}_a}{\rm{S}}{{\rm{i}}_{5 - a}}{({\rm{O}},{\rm{OH}})_{16}}]_y}{({\rm{B}}{{\rm{O}}_{\rm{3}}})_{32 - 4y}}{({\rm{HCl}},{{\rm{H}}_2}{\rm{O}})_n}\end{array} $$ where ymax= 8 and nmax= 16 – y. In this study, we examine samples of sakhaite and harkerite from four localities worldwide: Titovskoye deposit, Sakha Republic, Russia (type locality for sakhaite); Solongo B deposit, Buryatia Republic, Russia; Camas Malag, Skye, Scotland (type locality for harkerite); as well as a sakhaite-like mineral from the Kombat Mine, Tsumeb. The Si:B ratios of the samples ranged from that of end-member sakhaite (containing B only) to that of end-member harkerite (Si:B = 1:1), with several intermediate compositions. All samples were deficient in B relative to the ideal composition, implying significant substitution for borate groups. The Si:Al ratio of silicate-containing samples ranged from the ideal 4:1 to 4:1.5, implying substitution of Al at the Si site. The cubic unit-cell parameter was found to increase linearly with increasing Si content, except for the sakhaite-like mineral from Tsumeb. This mineral was found to have significant substitution of Pb for Ca (0.4–0.5 apfu) and was poor in Cl, which in most sakhaite and harkerite samples occupies the interstitial site surrounded by four borate groups. This interstitial site in the Tsumeb samples appears to be, instead, mainly occupied by H2O, which may qualify the mineral as a distinct species.

Natural samples of the rare earth element (REE)-bearing silicate minerals cerite, mosandrite, kainosite, zircon, and eudialyte were studied using reflectance spectroscopy in the visible to short-wave infrared regions (500 to 2500 nm) and further characterized by scanning electron microscopy and electron microprobe analysis. Spectral features of these minerals are driven primarily by 4f-4fintraconfigurational electronic transitions of trivalent lanthanides, as well as 5f-5felectronic transitions of uranium and vibrational overtones and combinations of H2O and OH–. Spectra of eudialyte are also impacted by relative amounts of IVFe2+and VFe2+. Respective spectra of these REE-bearing silicate minerals are sufficiently distinct to enable spectral classification. Spectral variability (e.g., band depths and locations) of some specific REE-related absorptions, such as an Er3+- and Yb3+-related absorption near 978 nm and Nd3+-related absorptions near 746, 803, and 875 nm, are interpreted to be driven by cation site differences in the crystal structures. This work adds to the growing understanding of REE-bearing mineral reflectance spectroscopy, which facilitates detection, identification, and quantification of REE-bearing silicate minerals in remote sensing applications. This is especially relevant for hyperspectral imaging spectroscopy with high spatial resolutions where the spectral response of a pixel becomes increasingly dominated by mineralogy rather than lithology.

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.

Reflectance spectroscopy in the visible to short-wave infrared regions (500 to 2500 nm) was carried out using natural samples of the rare earth element (REE) phosphate minerals monazite, xenotime, and britholite. Samples were characterized by scanning electron microscopy and electron microprobe analysis. Absorption band positions were recorded with their probable origins, and spectral variability among the samples is discussed. Spectral features of these minerals are driven primarily by 4f-4fintraconfigurational electronic transitions of trivalent lanthanides. The distinct REE distributions of monazite, xenotime, and britholite drive their bulk spectral patterns, which in turn are sufficiently distinct to enable spectral classification. Spectral variability of some specific REE-related absorptions are interpreted to be driven by differences of the co-ordination polyhedra for the lanthanide cations between the crystal structures. Spectra of these minerals were also compared against carbonatite-hosted REE bearing fluorapatite. The work presented here strengthens the growing foundation for the interpretation of reflectance spectra of these REE phosphate minerals and enables exploitation of the observed features by the remote sensing community for detection, identification, and quantification of REE phosphate minerals. This is especially relevant for hyperspectral imaging spectroscopy with high spatial resolution, where the spectral response of a pixel becomes increasingly dominated by mineralogy.

This study provides new insights into the relation between thermally induced structural reorganization and the macroscopic mechanical properties of radiation-damaged titanite. The natural sample contains ca. 30% amorphous fraction. Low-temperature annealing affects only slightly the sample stiffness and leads to a softening resulting from the defect annihilation in crystalline regions. In the high-temperature annealing regime, amorphous domains recrystallize and this leads to further recovery of defects, reduction of interfaces, grain growth, and, in general, an increase in the long-range order. The thermally induced recrystallization is accompanied by massive dehydration leading to considerable stiffening and hardening. This interpretation of the recrystallization process in titanite based on the correlation of new results from nanoindentation and Raman-spectroscopic measurements complementing previous investigations using thermogravimetric and gas analyses by Hawthorne et al. (1991)and infrared spectroscopy by Zhang et al. (2001). The new data combined with previous work leads to a detailed description of the annealing behavior of a radiation-damaged titanite, which is a complicated process that includes dehydration and atomic-scale structural reorganization. To minimize the influence of surface phenomena on the hardness measurements, the so-called “true” hardness was used instead of the standard hardness calculation (Oliver and Pharr 1992). A comparison shows that the Oliver and Pharr method clearly underestimates the hardness.

An understanding of the mineralogy and petrogenesis of rare earth element deposits has significant implications for their economic viability. Lanthanide-bearing compounds are known to produce sharp absorption features in the visible to short-wave infrared region (VIS-SWIR), however, a significant knowledge gap exists between the fields of hyperspectral reflectance spectroscopy and rare earth element mineralogy. Reflectance spectra were collected from four bastnäsite samples, two parisite samples, and one synchysite sample from the visible into the short-wave infrared. These REE fluorocarbonate mineral samples were characterized via scanning electron microscopy and electron probe microanalysis. Sharp absorptions of REE-bearing minerals are mostly the result of 4f-4f intraconfigurational electron transitions and for the light REE-enriched fluorocarbonates, the bulk of the features can be ascribed to Nd3+, Pr3+, Sm3+, and Eu3+. The lanthanide-related spectral responses of the REE fluorocarbonates are consistent across the group, supporting the notion that the REE cation site is very similar in each of these minerals. Carbonate-related spectral responses differed between these minerals, supporting the notion that the crystallographic sites for the carbonate radical differ between bastnäsite, synchysite, and parisite. Exploitable spectral differences include a distinct absorption band at 2243 nm that separates bastnäsite from synchysite and parisite. Similarly, for bastnäsite a dominantly Pr3+-related absorption band located is at 1968 nm, while in synchysite and parisite it occurs at 1961 nm.

Green vesuvianite crystals occur with garnet and calcite in a hand specimen from the Nedvedice marble near Kozlov (near Štepánov nad Svratkou, Svratka Crystalline Complex) in the Czech Republic. The average electron microprobe composition of the vesuvianite shows 12.10 wt% Fe2O3(4.66 Fe pfu), 2.77 wt% B2O3(2.45 B pfu), 1.71 wt% As2O5(0.46 As pfu), and 1.40 wt% F (2.26 F pfu). The Fe concentration is the highest ever recorded for a vesuvianite-group mineral. The boron contents are extremely variable and two of the five compositions show more than the 2.50 B pfu needed for wiluite, and the average is only slightly less than this. The crystal structure [a = 15.7250(4), c = 11.7736(3) Å was refined in space group P4/nnc to an R1value of 0.0221. The site refinement and Mössbauer spectroscopy results show Fe2+substituting for Ca at the X3 site and filling the Y1 position, and Fe3+substituting for Al at the Y3 position. Most of the Fe (70% from the site refinements and 78% from the Mössbauer interpretation) is ferric. The main effect of the high-Fe concentration is to increase the mean Y3-O distance to an unusually large 2.018 Å. Boron occurs at the T1 site, where it is coordinated by oxygen atoms at two O7B and two O11 positions, and at the T2 sites where it is coordinated by O atoms at one O10 and two O12A sites. When the nearby X3 site contains Fe, the T2 position is either vacant or [3]-coordinated by some combination involving an O10 site and two O12B positions, in which case the B atom is likely offset from the T2 site to reduce the B-O12B distance.

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).

Red vesuvianite crystals occur with hausmanite and calcite in a hand specimen from Långban, Sweden. Backscattered electron imaging revealed that a very few of the vesuvianite crystals exhibit cores of higher average atomic number (vesuvianite I) than the bulk (vesuvianite II). Average electron microprobe compositions of vesuvianite I show 3.32 wt% MnO (1.43 Mn2+apfu), 3.13 wt% Bi2O3(0.41 Bi3+apfu), 0.82 wt% Cl (0.71 Cl apfu), and 0.56 wt% As2O5(0.15 As5+apfu). The average vesuvianite II composition shows considerably more Mn (4.14 wt% MnO, or 1.76 Mn2+apfu) but less Bi (0.62 wt% Bi2O3, or 0.08 Bi3+apfu) and Cl (0.13 wt% Cl, or 0.11 Cl apfu) and about the same amount of As (0.62 wt% As2O5, or 0.16 As5+apfu). The crystal structures of vesuvianite I (a = 15.595, c = 11.779 Å) and II (a = 15.585, c = 11.778 Å) were refined in space group P4/nnc to R1 values of 0.0445 and 0.0167, respectively. The results show Bi at the new Bi3 position and Cl at the new Cl site; Bi3 can only be occupied when there is a vacancy at the nearby (~0.4 Å) X3 position, and Cl when there is a vacancy at the nearby (~0.4-0.5 Å) O10 position. Bond distances and site occupancies suggest that the Cl atom at the Cl site is bonded to the Bi atom at the Bi3 position when it is occupied. Arsenic occupies the T1 site and is coordinated by oxygen atoms at two O7B and two O11 positions. Manganese replaces Ca at the X1 and X2 position and dominates the Y1 position in vesuvianite I, whereas in vesuvianite II it replaces Ca at the X1 site and fills the Y1A position. In both structures Mn also occurs subordinate to Al + Mg at the Y3 position. Bond-valence analysis indicates that the Mn at the Y1 and Y1A positions is divalent rather than trivalent as required for manganvesuvianite.

The structural state of metamict titanite was studied by Raman spectroscopy, complementary high-resolution transmission electron microscopy, and single-crystal X-ray diffraction. The results show that Raman scattering collected from metamict titanite is highly anisotropic, which is typical of single crystals. But surprisingly, the observed Raman-scattering dependence on the sample orientation is much more pronounced for heavily metamict than for weakly metamict titanite samples. These radiation-induced anisotropic effects are related to the specific atomic arrangements in metamict titanite. The Raman spectra collected in backscattering geometry from a plane nearly perpendicular to the chains of corner-sharing TiO6octahedra arise predominantly from phonon modes in crystalline nanoregions with radiation-induced defects, whereas the contribution of atomic vibrations in radiation-induced amorphous nanoregions is better pronounced in the Raman spectra collected from a plane containing TiO6chains. This difference provides a unique opportunity to study separately, the structural transformations of the crystalline and amorphous fractions in metamict titanite. The results show that the radiation-induced periodic faults in the crystalline matrix are related to the disturbance of SiO4-TiO6-SiO4-TiO6rings comprising TiO6octahedra from different chains, whereas the radiationinduced amorphization is related to the partial change of Ti coordination from octahedral to pyramidal and/or tetrahedral, which in turn violates the Ti-O-Ti intrachain linkages. This indicates that the plane containing Si-O-Ti-O bond rings is less susceptible to a self-accumulation of radiation-induced defects resulting in the development of amorphous regions as compared to the perpendicular plane containing Ti-O bond chains. Sample-orientation-dependent Raman spectroscopy was further applied to annealed metamict titanite to give further insight into the temperature-driven recovery processes in the crystalline and amorphous nanoregions. Multistep annealing by 50 K for 2 h per step gradually suppresses the structural defects in the crystalline fraction as the improvement of the SiO4-TiO6connectivity within planes nearly perpendicular to the TiO6chains reaches saturation near 900 K. The annealing-induced recrystallization of the radiation-induced amorphous nanoregions takes place in the temperature range between approximately 650 and 950 K, with a maximum near 750 K. Raman scattering shows that multistep annealing up to 1173 K is insufficient to recover the crystalline structure of the studied metamict titanite sample, which has an accumulated radiation dose of 1.2 × 1018α-event/g.

We have measured the elastic response of radiation-damaged titanite, CaTiSiO5, as a function of thermal annealing. We estimate the bulk modulus of the damaged samples (-24% amorphous) to be 85 GPa, which is much softer than for undamaged crystalline titanite [131.4 GPa; Angel et al. (1999)]. Conversely, the lowest shear modulus of the radiation-damaged material is 52-58 GPa, which is harder that of the undamaged titanite, 46-52 GPa. The bulk and shear moduli of the radiation-damaged materials are close to those of thermal titanite glass, Bglass≈ 75 GPa and Gglass≈ 47 GPa, and are much smaller than expected based on other radiation-damaged materials such as zircon (ZrSiO4). Surprisingly, annealing of the damaged titanite in the range 600 < T < 1000 K leads to additional massive softening of the shear moduli. During annealing the shear modulus of titanite sample 1 softened from 58 to 29 GPa, and sample 2 softened from 52 to 19 GPa. The temperature range for the softening coincides with that found for crystallization of the amorphous regions, as measured previously by diffraction and spectroscopic methods. In contrast to the huge softening of the ultrasonically measured shear modulus, the calorimetrically measured Debye temperature θDincreases by -5%, suggesting a small intrinsic hardening of the acoustic shear modes. Additional heating to 1473 K leads, in one titanite sample, to a steep increase of the shear modulus to values much larger than that of the initial, radiation-damaged material. Theoretical models are discussed to rationalize the massive softening due to both radiation damage and subsequent anneal.

Joëlbruggerite, ideally Pb3Zn3(Sb5+,Te6+)As2O13(OH,O), is a new arsenate mineral (IMA 2008-034) and the Sb5+analog of dugganite, from the Black Pine mine, 14.5 km northwest of Philipsburg, Granite County, Montana. It is usually found perched on mimetite; other species that may be present include malachite, azurite, pseudomalachite, chalcocite, beudantite-corkite, duftite, dugganite, and kuksite, in milky quartz veins. Joëlbruggerite occurs as barrel-shaped or prismatic crystals up to about 50 μm across in various shades of purple. The crystals have an adamantine luster and a white streak. Mohs hardness is about 3. The fracture is irregular, and the tenacity is brittle. Joëlbruggerite crystals are uniaxial (-), with a calculated refractive index of n = 1.993, and weakly pleochroic: X = Y = gray, Z = purple; absorption: Z > X = Y. Crystals show straight extinction and are length-fast. The empirical chemical formula (mean of 5 electron microprobe analyses) calculated on the basis of 14 [O + OH] anions is Pb3.112(Zn2.689Fe2+0.185)Σ2.874(Sb5+0.650Te6+0.451)Σ1.101(As1.551P0.203Si0.160)Σ1.914O13.335(OH)0.665. Joëlbruggerite is trigonal, space group P321, a = 8.4803(17), c = 5.2334(12) Å, V = 325.94(12) Å3, Z = 1. The five strongest lines in the powder X-ray diffraction pattern are [dobs in Å (I) (hkl)]: 3.298 (100) (111), 3.008 (89) (021), 1.905 (39) (122, 131), 2.456 (36) (012, 121, 030), and 1.609 (30) (112, 132, 231, 140). The crystal structure was solved from single-crystal X-ray diffraction data and refined to R1= 0.038 on the basis of 604 unique reflections with F > 4σ(F). It is composed of heteropolyhedral sheets of edge-sharing (Sb,Te)O6octahedra and PbO8disphenoids, oriented parallel to (001). The sheets are cross-linked by AsO4and ZnO4tetrahedra, which share corners to form an interlinked, two- and threeconnected two-dimensional net parallel to (001). The mineral is named for Joël Brugger (born 1967), Swiss-Australian mineralogist, for his contributions to mineralogy.

We report on temperature dependencies of infrared (IR) fundamental, combination, and overtone vibrations of hydroxyl species (OH) in nominally anhydrous minerals (e.g., titanite), ferroelectric crystals (KTa1-xNbxO3, KTN), layer silicates (talc, mica, and pyrophyllite), and hydrous minerals such as apatite and synthetic hydrous/deuterated garnets [Ca3Al2(O4H4)3and Ca3Al2(O4D4)3] for the temperature range of 20-300 K. Data obtained by high-resolution FTIR spectroscopy show that increasing temperature generally leads to a decrease in the band height and band area of fundamental vibrations of hydroxyl species, whereas the combination and first-overtone bands commonly show different temperature dependencies. The results show that in the investigated temperature range, the variations of the band height and area for different OH bands (especially for combinations and overtones) on cooling or heating do not reflect changes in OH concentrations in the materials, but relate to temperature-dependent absorption coefficients. The observations imply that absorption coefficients calibrated at room temperature cannot necessarily be used for the determination of hydroxyl contents at other temperatures

The influence of F substitution on the local structure of Al in the tetrahedral and octahedral sheets of synthetic Al-rich phlogopite samples with nominal gel compositions of K(Mg3-xAlx)[Al1+xSi3-xO10] (OH)y(F)2-ybetween 0.0 ≤ x ≤ 0.8 and 0.5 ≤ y ≤ 1.8, was studied by 27Al MAS, MQMAS, {1H/19F} → 27Al 2D CPMAS (HETCOR) and {1H/19F} 27Al REDOR solid-state NMR and by IR spectroscopy. Changes in intensity of the absorption bands in the OH-stretching region of the IR spectra clearly indicate the incorporation of octahedral Al. Signals from the different phases can be separated in the 27Al MQMAS NMR spectra by generation of an isotropic dimension in F1. The 27Al quadrupolar parameters of the four phases were estimated from 27Al MAS NMR spectra obtained at 104.26 and 208.42 MHz. The quadrupolar coupling constant and isotropic chemical shift increases with increasing Al content for the IVAl site in phlogopite. The VIAl site shows a clear increase of the asymmetry parameter and CQwith increasing F content. The estimated 27Al signal areas show the lowest amount of impurity phases at high OH contents and a stabilization of VIAl sites by hydroxyl groups. The {1H} → 27Al 2D CPMAS (HETCOR) NMR experiment at short contact times provides information about site neighborhoods of tetrahedral Al sites and Mg3OH as well as Mg2AlOH sites, whereas magnetization is only transferred to the octahedral Al sites from hydroxyl groups in Mg2AlOH sites. The {19F} → 27Al 2D CPMAS (HETCOR) NMR spectrum is dominated by IVAl sites coupled to the Mg3F complex in phlogopite. Resonances from Mg2AlF complexes are not observed. Finally, the {1H/19F} 27Al REDOR experiments support the results of the 2D CPMAS (HETCOR) experiments.

The amblygonite-montebrasite series of minerals, common constituents of granitic pegmatites and topaz-bearing granites, show complete solid solution with ideal composition LiAlPO4(F, OH). These compounds are ideal for studying F ↔ OH solid solution in minerals because natural members of the series generally show little deviation from the ideal composition. In this study, we used powder and single-crystal neutron diffraction and solid-state 6Li MAS, CP MAS, and REDOR NMR techniques to study the effect of F ↔ OH substitution on the series. Lattice parameters refined from single-crystal neutron diffraction data show increasing b and decreasing a, c, and V with increasing F/(F + OH). The volume is highest for the OH end-member because of the presence of an additional atom (H). The a and c parameters decrease with increasing F/(F + OH) because the O-H vector is close to the a-c plane and the Al-OH/F vectors are approximately parallel to c.

The influence of F content on the formation and stability of Al-rich phlogopite has been investigated. Samples with varying OH/F-ratios and nominal gel compositions of K(Mg3-xAlx)(Al1+xSi3-xO10)(OH)y (F)2-y(0.0 < x < 0.8 and 0.5 < y < 1.8) were studied using 29Si, 1H, and 19F MAS NMR spec­troscopies, powder X-ray diffraction, electron-probe microanalysis, and scanning electron mi­croscopy. The synthetic phlogopites were synthesized from sol-gels in cold-seal pressure vessels at 1073 K, 2 kbar. The main phase (phlogopite) and three other impurity phases [corundum (α-Al2O3), kalsilite (KAlSiO4), and potassium aluminum hexafluoride (K3AlF6-0.5H20)] were clearly identi­fied by powder X-ray diffraction and electron-probe microanalysis. For phlogopite, the unit-cell parameters a0and b0decrease whereas C0increases with increasing Al-content (x). The average crystal size of phlogopite is about 1-2 pm. The 29Si MAS NMR spectra show up to four resonances at approximately -91, -87, -83, and -80 ppm, which can be assigned as Q3(n Al) signals with n = 0 - 3. The ideal Si/ivAl ratio calculated from the initial composition is always lower than that derived experimentally. Hydroxyl-rich compositions indicate an increased Al-content in the tetrahedral sheets, suggesting a stabilizing effect on the formation of Al-rich phlogopite. These conclusions are sup­ported by 1H and 19F MAS NMR spectra. The 1H MAS NMR spectra show a water signal at 4.7 ppm, a signal due to Mg2AlOH at 1.8 ppm, and a signal due to Mg3OH at 0.7 ppm. The 19F MAS NMR spectra exhibit a signal for Mg2AlF at -150 ppm, one due to AlF6(K3AlF6-0.5H20) at -157 ppm, and one for Mg3F at -174 ppm. Comparison of the 1H and 19F MAS NMR spectra for different Al- and F- contents reveals a non-statistical distribution of F- and OH-groups at the crystallographic sites in the octahedral sheets where F prefers sites coordinated by three Mg, and OH sites with Al in the next- nearest coordination sphere.

The amblygonite-montebrasite series of minerals, common constituents of granitic pegmatites and topaz-bearing granites, show complete solid solution with ideal composition LiAlPO4(F, OH). These compounds are ideal for studying F ↔ OH solid solution in minerals because natural members of the series generally show little deviation from the ideal composition. In this study, we used powder and single-crystal neutron diffraction and solid-state 6Li MAS, CP MAS, and REDOR NMR techniques to study the effect of F ↔ OH substitution on the series. Lattice parameters refined from single-crystal neutron diffraction data show increasing b and decreasing a, c, and V with increasing F/(F + OH). The volume is highest for the OH end-member because of the presence of an additional atom (H). The a and c parameters decrease with increasing F/(F + OH) because the O-H vector is close to the a-c plane and the Al-OH/F vectors are approximately parallel to c.

Radiation damage and the recrystallization of natural titanite (CaTiSiO5) were studied using infrared spectroscopy in the spectral range from 50 to 7500 cm-1. The results show that radiation damage leads to systematic changes in spectral features: decreasing absorption and reflectivity, line broadening, and loss of orientational dependence. Strongly damaged titanite shows hydroxylate bands between 2200 and 3500 cm-1. The band most affected by radiation damage is the Ti-O stretching band near 670 cm-1. It shifts to 710 cm-1in the most damaged samples, possibly indicating the presence of TiO5complexes in metamict titanite. Titanite glasses (quenched melts of CaTiSiO5) show spectral features different from those of radiation-damaged titanite, especially in the Ti-O and Si-O stretching regions.

Radiation damage and the recrystallization of natural titanite (CaTiSiO5) were studied using infrared spectroscopy in the spectral range from 50 to 7500 cm-1. The results show that radiation damage leads to systematic changes in spectral features: decreasing absorption and reflectivity, line broadening, and loss of orientational dependence. Strongly damaged titanite shows hydroxylate bands between 2200 and 3500 cm-1. The band most affected by radiation damage is the Ti-O stretching band near 670 cm-1. It shifts to 710 cm-1in the most damaged samples, possibly indicating the presence of TiO5complexes in metamict titanite. Titanite glasses (quenched melts of CaTiSiO5) show spectral features different from those of radiation-damaged titanite, especially in the Ti-O and Si-O stretching regions.

The content of hydrous species in crystalline and metamict titanite (CaTiSiO5) have been investigated using polarized infrared spectroscopy. The effects of metamictization are a decrease of intensity and a broadening of Ti-O and Si-O stretching overtones, accompanied by development of the isotropic spectral features of hydrous species. Metamict and partially metamict titanites show OH contents up to 0.73 wt% H2O on the basis of previously reported calibrations. On heating, crystalline and metamict titanite showed a different temperature evolution of their OH content. Thermal annealing of crystalline titanite at temperatures above 1100 K for 15 min resulted in dehydration, characterized by a dramatic decrease in the intensity of the OH signal near 3486 cm-1, in contrast to a two-stage dehydration process in metamict titanite. The results show that the high OH contents in metamict titanites are probably due to hydrogen diffusion during and after metamictzation. The results also show that the recrystallization in metamict titanite at high temperatures involves epitaxial growth of crystalline domains.

A Cs-Li-analogue of cancrinite has been synthesized from tetraethoxysilane and Al sec-butoxide in a mixture of 1,3-butanediol and water. Cs and Li were introduced as hydroxides. Synthesis was done at autogeneous pressure and T = 473 K for 100 h. The synthesis product was characterized by powder X-ray diffraction, IR-spectroscopy, thermogravimetry, 1H, 6Li, 7Li, 133Cs, 27Al, 29Si MAS, and {1H} 13C CPMAS NMR and Rietveld structure refinement. 29Si MAS NMR and 27Al MAS NMR spectroscopy show a framework with strong alternating order of the SiO4and AlO4tetrahedra and an Si/Al ratio of one. 6Li MAS NMR suggests the existence of two different signals that cannot be resolved in the 7Li MAS NMR spectrum. 133Cs MAS NMR shows only a single resonance. The thermogravimetric analysis reveals a continuous weight loss in several steps, indicating the evaporation of water of hydration. IR spectroscopy shows evidence for hydroxyl anions and water included in the cancrinite framework. The Rietveld structure refinement is consistent with a completely ordered alumosilicate framework with an Si/Al ratio of one and the presence of both molecular water and hydroxyl groups in the hexagonal channel, a result different from the previously published structure. Cs is exclusively located in the ε-cages; Li ions are located in the channels and are coordinated by water molecules.

The content of hydrous species in crystalline and metamict titanite (CaTiSiO5) have been investigated using polarized infrared spectroscopy. The effects of metamictization are a decrease of intensity and a broadening of Ti-O and Si-O stretching overtones, accompanied by development of the isotropic spectral features of hydrous species. Metamict and partially metamict titanites show OH contents up to 0.73 wt% H2O on the basis of previously reported calibrations. On heating, crystalline and metamict titanite showed a different temperature evolution of their OH content. Thermal annealing of crystalline titanite at temperatures above 1100 K for 15 min resulted in dehydration, characterized by a dramatic decrease in the intensity of the OH signal near 3486 cm-1, in contrast to a two-stage dehydration process in metamict titanite. The results show that the high OH contents in metamict titanites are probably due to hydrogen diffusion during and after metamictzation. The results also show that the recrystallization in metamict titanite at high temperatures involves epitaxial growth of crystalline domains.

A Cs-Li-analogue of cancrinite has been synthesized from tetraethoxysilane and Al sec-butoxide in a mixture of 1,3-butanediol and water. Cs and Li were introduced as hydroxides. Synthesis was done at autogeneous pressure and T = 473 K for 100 h. The synthesis product was characterized by powder X-ray diffraction, IR-spectroscopy, thermogravimetry, 1H, 6Li, 7Li, 133Cs, 27Al, 29Si MAS, and {1H} 13C CPMAS NMR and Rietveld structure refinement. 29Si MAS NMR and 27Al MAS NMR spectroscopy show a framework with strong alternating order of the SiO4and AlO4tetrahedra and an Si/Al ratio of one. 6Li MAS NMR suggests the existence of two different signals that cannot be resolved in the 7Li MAS NMR spectrum. 133Cs MAS NMR shows only a single resonance. The thermogravimetric analysis reveals a continuous weight loss in several steps, indicating the evaporation of water of hydration. IR spectroscopy shows evidence for hydroxyl anions and water included in the cancrinite framework. The Rietveld structure refinement is consistent with a completely ordered alumosilicate framework with an Si/Al ratio of one and the presence of both molecular water and hydroxyl groups in the hexagonal channel, a result different from the previously published structure. Cs is exclusively located in the ε-cages; Li ions are located in the channels and are coordinated by water molecules.

Synchrotron radiation, high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction, and Raman spectroscopy were used to study the structure and thermal behavior of malayaite, CaSnSiO5. No indications of deviation from A2/a symmetry and no structural transitions were observed between 100 and 870 K. HRTEM revealed that the material is free of domains and antiphase boundaries. However, the lattice constants, cell volume, and Raman-active phonons show a thermal discontinuity near 500 K, which is possibly related to variation of the coordination sphere around the highly anisotropic Ca position.

The crystal structure of namuwite, (Zn,Cu)4SO4(OH)6 · 4H2O, trigonal, a = 8.331(6), c = 10.54(1) Å, V = 634(1) Å3, P3̅, Z= 2, has been solved by direct methods and refined to an R index of 7.9% using MoΚα X-ray data. The fundamental building unit of the structure is a gently modulated sheet of edge-sharing (Zn,Cu) octahedra parallel to (001), with one vacancy for every six occupied octahedral sites. The sheets are decorated on both sides by SO4and [Zn(OH)3(H2O)]1-tetrahedra; the latter are located above and below the vacant octahedral sites. Adjacent tetrahedral-octahedral-tetrahedral (T-O-T) layers are held together by hydrogen bonds to interstitial H2O molecules.