Perfect Cleavage Research Articles

Who's Who in Mineral Names: Anthony J. Nikischer (b. 1949)

Nikischerite, ideally NaFe2+ 6Al3(SO4)2(OH)18(H2O)12, occurs as dark yellow-green micaceous plates to 4 mm, forming radiating balls and aggregates (Huminicki et al. 2003). The mineral has a dull to greasy luster, a pale grayish streak, and a Mohs hardness of 2. It has a perfect cleavage parallel to {001}, which is also the dominant form displayed by the platy crystals. The type locality is the Huanuni tin mine, Dalence Province, Oruro Department, Bolivia, where nikischerite occurs in and on a clay matrix, associated with minor pyrite, pyrrhotite, siderite, and cronstedtite.

Leogangite, Cu 10 (AsO 4 ) 4 (SO 4 )(OH) 6 ???8H 2 O, a new mineral from the Leogang mining district, Salzburg province, Austria

Leogangite, ideally Cu10(AsO4)4(SO4)(OH)6·8H2O, was found on sample material from mine dumps of the Danielstollen and Inschlagalm in the Schwarzleo valley, both part of the polymetallic ore district of Leogang, Salzburg province, Austria. It is intergrown with olivenite and malachite, all together coating small voids within a tennantite-bearing dolomite breccia, and is assumed to have formed as an alteration product of arsenic-rich fahlore. Associated minerals are tyrolite, parnauite, strashimirite, euchroite, brochantite, langite, posnjakite, and devilline. The new mineral crystallizes with monoclinic symmetry, space group C2/c (no. 15), with a=21.770(7) A, b=12.327(4) A, c=10.720(3) A, β=92.85(1)°, V=2873(2) A3, Z=4, and a calculated density of 3.55 g·cm−3. Leogangite exhibits a thin tabular habit with aggregates of platelets flattened on {100} and elongated along [010], measuring up to 0.1 mm in length, 0.05 mm in width, 0.01 mm in thickness. A perfect cleavage parallel to (100) can be observed. It is transparent, green with a bluish tint, the streak is light green, and it is optically negative with 2V=18(2)°. The refractive indices nx, ny, and nz are 1.590(2), 1.740(2), and 1.744(2), the optical orientation is X=a*, Y=b, Z=c, and the pleochroism is blue-green (X) to pale green (Y, Z). Typical microprobe analyses give (wt%) CuO 49.6–52.9, As2O5 28.5–31.1, SO3 4.9–5.4, which is equivalent to Cu9.94(As0.99Si0.01O4)4(S0.99O4)(OH)6·8.89H2O as the average composition based on 20+3 oxygens. The strongest reflections of the X-ray powder diffraction pattern are (dobs, I/Iobs, hkl): 10.85, 100, (200); 2.630, 60, (\({\it 20}{\bar {\it 4}}\)); 5.44, 50, (400); 3.625, 50, (600); 3.090, 40, (023). The structure of the mineral was refined to R1=0.095 for 1768 unique reflections with \(F^2_{\rm o} > 4\sigma(F^2_{\rm o})\) and is a new representative of the rare [5]-coordinated Cu2+ compounds with edge-sharing CuO5 square pyramids. The main motif consists of [Cu4O14] tetramers. Together with the AsO4 tetrahedra and the remaining CuO5 polyhedron they build complex heteropolyhedral layers parallel to (100), which are linked by the SO4 tetrahedron and parts of the hydrogen bonds along the a-axis, thus forming a complex open framework structure. Chemical, optical and X-ray powder pattern characteristics are the distinguishing features to similar minerals like parnauite, tyrolite, or clinotyrolite.

Structure and crystallization behavior of the (Ba,Sr)HAsO4·H2O solid-solution in aqueous environments

Crystals of different members of the (Ba,Sr)HAsO4·H2O solid solution have been synthesized, and the first structural studies indicate that they crystallize in the same space group, Pbca, with Z = 8. The unit-cell parameters are a = 7.436(2), b = 8.481(1), c = 14.348(6) Å, and a = 7.752(1), b = 8.759(1), c = 14.668(3) Å for the strontium and barium end-members, respectively. Both end-members have a layered structure with slices parallel to (001) linked by hydrogen bonds from the water molecules. These features are consistent with both the perfect cleavage on {001} and the morphological importance of this form in the crystals obtained. However, the two end-members are not isostructural and show differences in both the anionic hydrogen positions and number of hydrogen bonds. Complementary powder-diffraction measurements indicate that the cell parameters increase in a non-linear way with the barium content indicating that the solid solution is complete but could be non-ideal. Preliminary data suggest that barium partitions preferentially into the solid phase when crystallizing this solid solution from aqueous solutions.

Study of the orientation and frequency of occurrence of elementary steps on the (010) cleavage face of potassium acid phthalate single crystals

Experimental observations of an atomic force microscopy study of the orientation and frequency of occurrence of elementary steps of height 1.386 nm (equal to the lattice parameter b) produced on the freshly cleaved (0 1 0) surfaces of potassium acid phthalate crystals grown from aqueous solutions are described and discussed. It was found that most of the elementary cleavage steps are oriented along low-index crystallographic directions. The relative frequencies of the experimentally observed elementary steps of different orientations were compared with their calculated energies. Van der Waals interactions between neighbouring molecules and Madelung summation of Coulomb interactions between an ion and the surrounding ions were considered to calculate the total surface energy or the total energy of a step of a given orientation. It is shown that: (1) in the case of crystals like potassium acid phthalate containing both Coulomb and Van der Waals bonds, the calculated values of surface and step energies may be incorrect when they are considered purely ionic, (2) the relatively low value of the surface energy, mainly due to Van der Waals interactions, is responsible for the perfect cleavage along the (0 1 0) plane, and (3) some of the observed cleavage steps have orientations that correspond to low step energies.

Larisaite, Na(H3O)(UO2)3(SeO3)2O2 4H2O, a new uranyl selenite mineral from Repete mine, San Juan County, Utah, U.S.A.

Larisaite, a new uranyl selenite with the idealized formula Na(H3O)(UO2)3(SeO3)2O2 · 4H2O, has been found in a sedimentary rock from Repete mine near Blanding, San Juan Co., Utah, U.S.A., in association with quartz, haynesite, andersonite, wolsendorfite, uranophane, gypsum, calcite and montmorillonite. The mineral is named in memory of Russian mineralogist and crystallographer Larisa Nikolaevna Belova (1923–1998) who made a significant contribution to the knowledge on the uranium minerals. Larisaite forms coarse lamellar crystals up to 1 mm and radial aggregates up to 2 mm. It is transparent or translucent, yellow, lustre vitreous, streak yellow. Fluorescence under the UV light is green (wavelengths of excitation 250 nm). Larisaite is sectile, with Mohs' hardness 1, perfect cleavage on (010) and uneven fracture across the cleavage direction. Calculated density is 4.50 g/cm3 from the crystal structure refinement and 4.46 g/cm3 from the empirical formula. Optically biaxial (−), α 1.597(2), β 1.770(5), γ 1.775(5); −2V = 20°. Dispersion is strong, r α (light greenish-yellow). IR spectrum is given. Average values for 3 point microprobe analyses (wt.%, ranges are given in brackets) are: Na2O 2.04 (1.82–2.32), K2O 0.69 (0.62–0.76), CaO 0.23 (0.17–0.30), UO3 72.19 (71.77–72.64), SeO2 18.12 (17.83–18.48); H2O content determined by Penfield method is 7.64; total 100.91 wt.%; contents of Mg, Sr, Ba, Pb, Zn, Mn, Ni, Co, Cu, Fe, Al, Si, S, As, Cl, F are lower than detection limits i. e. 2)3.09(SeO3)2O24.1H20.1-(Kp/Kc) = 0.013 (“superior”). The crystal structure has been determined (R=0.067). Larisaite is monoclinic, space group P 11 m ; a = 6.9806(9), b = 7.646(1), c = 17.249(2) A, γ = 90.039(4)°, V = 920.64 A3, Z = 2. The strongest lines in the powder diffraction pattern [ d , A ( I , %) ( hkl )] are: 8.63 (43) (002), 7.67 (100) (010), 3.85 (40) (−113, 020, 113), 3.107(77) (211), 2.874 (53) (006, −115). By the U: Se ratio, the values of unit cell parameters and the structure type, larisaite is related to haynesite, guilleminite and piretite. In common with guilleminite, uranium polyhedra and SeO3 triangles form the sheets, however the distribution of interlayer cations and H2O molecules is different. Holotype specimen is deposited in the Geoscientific Collections of Freiberg University of Mining and Technology, Faculty of Geosciences, Geotechnics and Mining, Freiberg, Germany (the inventory number 80251).

Preparing Contamination-free Mica Substrates for Surface Characterization, Force Measurements, and Imaging

Due to its perfect cleavage that provides large areas of molecularly smooth, chemically inert surfaces, mica is the most commonly used natural substrate in measurements with the surface forces apparatus (SFA), in atomic force microscopy (AFM), and in many adsorption studies. However, preparing mica surfaces that are truly clean is not easy since mica is a high-energy surface that readily adsorbs water, organic contaminants, and gases from the atmosphere. Mica can also become charged on cleaving, which makes it prone to picking up oppositely charged particles or mica flakes from the surroundings. High refractive index particles, such as metals, will adhere to mica through van der Waals forces. Recent articles have demonstrated that particle contamination is obtained when inappropriate cutting and handling procedures for the mica are used. In this paper, we show that both particle and other critical contamination is easy to detect and provide proper steps to take during the sample preparation process.

Study of the orientation and frequency of occurrence of elementary steps on the (0 1 0) cleavage face of potassium acid phthalate single crystals

Experimental observations of an atomic force microscopy study of the orientation and frequency of occurrence of elementary steps of height 1.386 nm (equal to the lattice parameter b) produced on the freshly cleaved (0 1 0) surfaces of potassium acid phthalate crystals grown from aqueous solutions are described and discussed. It was found that most of the elementary cleavage steps are oriented along low-index crystallographic directions. The relative frequencies of the experimentally observed elementary steps of different orientations were compared with their calculated energies. Van der Waals interactions between neighbouring molecules and Madelung summation of Coulomb interactions between an ion and the surrounding ions were considered to calculate the total surface energy or the total energy of a step of a given orientation. It is shown that: (1) in the case of crystals like potassium acid phthalate containing both Coulomb and Van der Waals bonds, the calculated values of surface and step energies may be incorrect when they are considered purely ionic, (2) the relatively low value of the surface energy, mainly due to Van der Waals interactions, is responsible for the perfect cleavage along the (0 1 0) plane, and (3) some of the observed cleavage steps have orientations that correspond to low step energies.

POTASSIC-CARPHOLITE, A NEW MINERAL SPECIES FROM THE SAWTOOTH BATHOLITH, BOISE COUNTY, IDAHO, U.S.A.

Potassic-carpholite, ideally (K,) (Li,Mn 2+ )2 Al4 Si4 O12 (OH)4 (F,OH)4, is a new mineral species from the Sawtooth batholith, an anorogenic Tertiary granite pluton near Centerville, Boise County, Idaho, U.S.A. It occurs as irregular tufts (up to 2 mm across) of radiating acicular-to-fibrous crystals in miarolitic cavities in the granite, associated with quartz, microcline, albite, beryl, topaz, bertrandite, hellandite, zinnwaldite, fluorite, hematite and apatite. Individual crystals of potassic-carpholite are white to straw yellow with a white streak and a vitreous luster, and are non-fluorescent in ultraviolet light. Crystals are generally 20‐40 m across and approximately 500 m long and elongate along [100]. Potassic-carpholite is brittle with an irregular fracture on ends of the acicular crystals, and has a perfect cleavage parallel to {010}. Twinning was not observed. The Mohs hardness is ~5, and the observed and calculated densities are 3.08(2) and 3.06 g/cm 3 , respectively. Potassic-carpholite is biaxial negative, with 1.578, 1.592, 1.598, all ±0.002, 2V(obs.) = 57(2)°, 2V(calc.) = 66°, weakly pleochroic with X pale yellow, Y = Z colorless, with X > Y, Z and X = b, Y = a and Z = c. Potassic-carpholite is orthorhombic, space group Ccca, a 13.715(5), b

PLUMBIAN BAKSANITE FROM THE TYRNYAUZ W Mo DEPOSIT, BAKSAN RIVER VALLEY, NORTHERN CAUCASUS, RUSSIAN FEDERATION

A sample of Pb-rich baksanite was recovered in a magnetite‐andradite skarn from the Tyrnyauz W‐Mo deposit, in the northern Caucasus, Baksan River valley, Kabardino‐Balkaria Republic, Russian Federation. The rock sample forms part of the historical mineralogical collection of the Natural History Museum of the University of Florence. Associated minerals are bismuthinite, tetradymite, joseite-A and ingodite; gangue minerals are calcite and andradite. Electron-microprobe analyses gave the chemical formula (Bi4.94Pb0.96)5.90(Te2.03S3.06). The mineral occurs as anhedral grains up to 0.5 mm across. Plumbian baksanite is dark steel-grey, shows a black streak, and has a perfect basal cleavage. Its calculated density (for Z = 3) is 7.44 g/cm 3 for the empirical formula and 7.51 g/cm 3 inferred for (Bi5Pb)(Te2S3). The mineral is greyish white in reflected light, weakly bireflectant, nonpleochroic, faintly anisotropic in yellowish gray tints. Reflectivity values (Rmin and Rmax in %) are 47.2, 50.3 (471.1 nm), 47.9, 50.7 (548.3 nm), 48.2, 51.3 (586.6 nm), and 48.5, 51.4 (652.3 nm), respectively. Indexing of the X-ray powder pattern indicates trigonal symmetry, space group P¯ 3m1, with a 4.251(1), c 64.19(3) A, V 1063.4(6) A 3 . The theoretical structural model proposed for the original baksanite is confirmed, and a comparison of intensities in the X-ray-diffraction patterns of the two samples strongly indicates that the Bi‐Pb and Te‐S atoms are disordered at the same positions. Therefore, even if a nearly perfect stoichiometry among the elements is observed, this material is not a new species but merely a plumbian variety of baksanite.

The study of Bi 3B 5O 12: synthesis, crystal structure and thermal expansion of oxoborate Bi 3B 5O 12

The paper presents a new data on the crystal structure, thermal expansion and IR spectra of Bi 3B 5O 12. The Bi 3B 5O 12 single crystals were grown from the melt of the same stoichiometry by Czochralski technique. The crystal structure of Bi 3B 5O 12 was refined in anisotropic approximation using single-crystal X-ray diffraction data. It is orthorhombic, Pnma, a=6.530(4), b=7.726(5), c=18.578(5) Å, V=937.2(5) Å 3, Z=4, R=3.45%. Bi 3+ atoms have irregular coordination polyhedra, Bi(1)O 6 ( d(B–O)=2.09–2.75 Å) and Bi(2)O 7 ( d(B–O)=2.108–2.804 Å). Taking into account the shortest bonds only, these polyhedra are considered here as trigonal Bi(1)O 3 (2.09–2.20 Å) and tetragonal Bi(2)O 4 (2.108–2.331 Å) irregular pyramids with Bi atoms in the tops of both pyramids. The BiO 4 polyhedra form zigzag chains along b-axis. These chains alternate with isolated anions [B 2 IVB 3 IIIO 11] 7− through the common oxygen atoms to form thick layers extended in ab plane. A perfect cleavage of the compound corresponds to these layers and an imperfect one is parallel to the Bi–O chains. The Bi 3B 5O 12 thermal expansion is sharply anisotropic ( α 11≈ α 22=12, α 33=3×10 −6 °C −1) likely due to a straightening of the flexible zigzag chains along b-axis and decreasing of their zigzag along c-axis. Thus the properties like cleavage and thermal expansion correlate to these chains.

PARAVINOGRADOVITE, (Na, )2 [(Ti4+,Fe3+)4 {Si2 O6}2 {Si3 Al O10} (OH)4] H2O, A NEW MINERAL SPECIES FROM THE KHIBINA ALKALINE MASSIF, KOLA PENINSULA, RUSSIA: DESCRIPTION AND CRYSTAL STRUCTURE

Paravinogradovite is a new mineral species from Mount Kukisvumchorr, Khibina alkaline massif, Kola Peninsula, Russia. Paravinogradovite forms prismatic crystals elongate along [100] and up to 0.5–1.0 cm long; crystals in some cases occur in fan-shaped aggregates sporadically scattered throughout a matrix of feldspar, nepheline and natrolite in a strongly mineralized nepheline–feldspar pegmatite. Associated minerals are nepheline, K-feldspar, albite, analcime, natrolite, aegirine, biotite, chlorite, zircon, ilmenite, pyrochlore, ancylite-(Ce), nordstrandite, carbonate-fluorapatite, fluorite, galena and cerussite. Crystals of paravinogradovite are colorless to white, with a white streak and a luster that varies from vitreous to pearly. The mineral is translucent to transparent, and shows weak yellow-green fluorescence under 240–400 nm ultraviolet radiation. Paravinogradovite has a perfect cleavage on {001} and an indistinct cleavage on {010}. It is brittle, has a splintery fracture and a Mohs hardness of 5. Its observed and calculated densities are 2.77(2) and 2.76 g/cm 3 , respectively. It is biaxial negative with α 1.707(2), β 1.741(2), γ 1.755(2), 2 V (obs.) = 64(1)°, 2 V (calc.) = 64°, nonpleochroic with dispersion r > v , with Z ≈ b , X ∧ a = 30°. Paravinogradovite is triclinic, space group P 1, a 5.2533(1), b 8.7411(3), c 12.9480(5) A, α 70.466(1), β 78.472(1), γ 89.932(1)°, V 547.65(5) A 3 , Z = 1. The strongest seven lines in the X-ray powder-diffraction pattern [ d in A( I )(( hkl )] are: 3.182(100)(013,014), 5.88(65)(011,012), 11.9(58)(001), 4.35(38)(021,102), 5.98(35)(002), 3.085(29)(123) and 2.735(21)(122). Chemical analysis by electron microprobe gave SiO 2 43.54, Al 2 O 3 6.12, Fe 2 O 3 4.11, Nb 2 O 5 0.50, TiO 2 29.59, BeO 0.76, MgO 0.13, Na 2 O 7.77, K 2 O 0.87, H 2 O 6.23, sum 99.62 wt.%, where the amount of Be and the amount of H 2 O were determined by crystal-structure analysis, and the valence state of Fe was determined by Mossbauer spectroscopy. The resulting empirical formula on the basis of 26 anions (including OH = 4 apfu and excluding H 2 O) is (Na 2.293 K 0.169 ) (Ti 3.386 4+ Fe 0.471 3+ Mg 0.029 Nb 0.034 ) (Si 6.626 Al 1.098 Be 0.276 ) O 22 (OH) 4 (H 2 O) 1.16 . There are prominent endothermic effects at 280 and 460°C; the principal losses in weight are within the temperature ranges 150–400 (3.8%) and 400–600°C (2.8%), and the total loss in weight at 980°C is 7.1%. The principal absorptions in the infrared are as follows: 3520, 3330, 3240, 1633, 1105, 989, 940, 725, 691, 638, 599, 568, 523, 459 and 418 cm −1 , indicative of both OH and H 2 O in the structure. The name recognizes the close structural and chemical relations between paravinogradovite and vinogradovite, ideally Na 5 Ti 4 4+ (Si 7 Al) O 26 (H 2 O) 3 . The crystal structure of paravinogradovite was solved by direct methods and refined to an R 1 index of 4.5% based on 4373 observed [ F o > 4σ F ] unique reflections measured with Mo K α X-radiation and a Bruker P 4 diffractometer with a CCD detector. Four (SiO 4 ) tetrahedra form pyroxene-like [Si 2 O 6 ] chains, and three (SiO 4 ) tetrahedra and one (AlO 4 ) tetrahedron form vinogradovite-like [Si 3 AlO 10 ] chains parallel to [100]. ( M O 6 ) octahedra ( M ≈ Ti 4+ ) share common edges to form two distinct zig-zag brookite-like chains along [100]. One chain is decorated by ( X O 6 ) octahedral ( X ≈ Na) and linked into a sheet parallel to (100) by [Si 3 AlO 10 ] chains. The other distinct brookite-like chain is not decorated by ( X O 6 ) octahedra, but is linked into a sheet parallel to (100) by [Si 3 AlO 10 ] chains. Chains of tetrahedra and chains of octahedra link to form a framework with channels along [100]. These channels contain disordered (H 2 O) groups, the A (5) site partly occupied (14%) by K, and the A (1)– A (4) sites partly occupied (15–19%) by Na, giving a channel content of [Na 0.72 K 0.14 (H 2 O) 1.16 ]. The triclinic cell of paravinogradovite is related to the C -centered monoclinic cell of vinogradovite, ideally Na 5 Ti 4 4+ (Si 7 Al) O 26 (H 2 O) 3 [monoclinic, a 24.490(10), b 8.657(4), c 5.203(2) A, β 100.2(0)° , V 1085.8 A 3 , space group C 2/ c , Z = 2] by the matrix transformation (0 0 1, 0 1 0, −½ 1 0).

New rubidium pentaborate Rb[B5O7(OH)2] · 0.5H2O with a 5: [4Δ + 1T] anionic block and its relation to larderellite (NH4)[B5O7(OH)2] · H2O on the basis of the OD theory

A new rubidium pentaborate is synthesized under hydrothermal conditions. Its crystal structure is studied by the heavy-atom method without any a priori knowledge of chemical formula. The chemical formula is Rb[B5O6(OH)4] · 0.5H2O, sp. gr. \(\bar P1\), lattice parameters a = 7.679(4) A, b = 9.253(6) A, c = 12.053(9) A, α = 98.55(5)°, β = 106.80(5)°, γ = 91.71°, R = 0.0573, Rw = 0.0638, S = 1.07. The anionic part of the structure consists of a chain of fundamental building blocks 5:[4Δ + 1T] built by four B triangles bound to one B tetrahedron, which are common to Na, K, Rb, and Cs pentaborates. This new pentaborate is closely related to the mineral larderellite (NH4)[B5O6(OH)4] · H2O but possesses an original structure, which manifests itself in the different morphology of the new pentaborate and the absence of perfect cleavage. The Dornberger-Schiff OD theory allows one to describe in detail the structural relationships, predict possible hypothetical structures, and write the OD groupoid.

Borocookeite, a new member of the chlorite group from the Malkhan gem tourmaline deposit, Central Transbaikalia, Russia

Borocookeite, ideally Li 1+3 x Al 4– x (BSi 3 )O 10 (OH,F) 8 (where “ x ” varies in the range 0.00–0.33 apfu), in which [4] Al is replaced by B relative to cookeite, occurs as a late-stage pocket mineral in the Sosedka and Mokhovaya pegmatite veins, Malkhan gem tourmaline deposit, Chikoy district, Chita oblast, Russia. Borocookeite proper, as well as boron-rich cookeite, is light grey with a pinkish or yellow hue and occurs as a dense, massive crypto-flaky aggregate or thin crusts and snow-like coatings on crystals of quartz, tourmaline, and feldspars from miarolitic cavities. Fragments of elbaite, danburite, and albite are included in the borocookeite mass. In some pockets, the coating is composed of borocookeite and boron-rich muscovite (or boromuscovite) which are not distinguishable visually. Chemical analysis yields (wt%): SiO 2 34.19, TiO 2 0.02, Al 2 O 3 41.77, FeO 0.06, MnO 0.07, MgO 0.04, CaO 0.08, Na 2 O 0.01, K 2 O 2 O 4.65, Rb 2 O 0.004, Cs 2 O 0.005, B 2 O 3 4.06, BeO 0.05, H 2 O + 14.17, H 2 O– 0.11, F 1.22, −O = F 0.51, total 100.00. The empirical formula calculated on the basis of 28 positive charges is: Li 1.61 Al 3.80 (Al 0.44 B 0.60 Be 0.01 Si 2.95 ) ∑ 4.00 O 10 [F 0.33 (OH) 7.81 ] ∑ 8.14 . The unit- cell parameters, calculated from X-ray powder diffraction data, are a = 5.110(4), b = 8.856(3), c = 14.080(6) A, β = 96.93° (4) these values are smaller than those for cookeite. D calc = 2.69(1) g/cm 3 . The mineral has a Mohs hardness of 3, light pinkish-grey streak, greasy luster, perfect (001) cleavage, and no parting or fracture. Optical properties (for white light): α = 1.574, β = 1.580, γ = 1.591 (all ± 0.002), 2 V calc = 72°, dispersion not determined. The optical sign and the angle of the optical axis were not measured because of the small size and strong curvature of the mineral flakes. Borocookeite, as well as other boron-rich phyllosilicate minerals, crystallized from evolved residual solutions in miarolitic cavities at temperatures not less 265–240 ° C. The ratio of activities of K, Li, B, F, and H 2 O in the mineral-forming fluids of isolated evolving pockets determined whether borocookeite or boromuscovite formed separately or together.

Who's Who in Mineral Names: Anthony Robert Kampf (b. 1948)

Kampfite, ideally Ba6Si8O16(CO3)4Cl2, forms pale blue-gray irregular masses to 10 mm enclosed in quartz-rich portions of sanbornite-bearing rock in the barium-silicate-rich deposits at Big Creek and Rush Creek, Fresno County, California (Basciano et al. 2001). The mineral is translucent and has a vitreous luster, white streak, hardness of 3, and density of 3.5 g/cm3. It is brittle with uneven fracture and one perfect cleavage on {001}. Associated minerals include celsian, fresnoite, macdonaldite, pyrrhotite, titantaramellite, traskite, witherite, and two other new minerals. The deposit probably began as sediments of Paleozoic age that were metamorphosed prior to being uplifted to their present position.

Santabarbaraite: a new amorphous phosphate mineral

SantabarbaraiteisanewamorphousferricironhydroxyphosphatehydratefromValdarno,Tuscany,Italy,thetypelocality, and Wannon Falls, Victoria, Australia. The mineral is the result of in situ oxidation of vivianite, occurring as pseudomorphs after vivianite crystals that are up to 3 mm across in concretionary nodules at the type locality and somewhat larger at Wannon Falls. Santabarbaraite is brown to light-brown in hand specimen, but appears yellowish amber under the microscope and has a similar streak. It is translucent with a distinct vitreous to greasy lustre and is nonfluorescent. It is brittle with a distinct parting along the perfect cleavage of vivianite. The hardness was not measured but the measured density of the type material is 2.42 g/cm 3 . Optically isotropic, the mineral has a refractive index of 1.695(5). The empirical formula for the type material is (Fe 2.64Mn0.13Mg0.07) (PO4)2 (OH)2.45 · 5.1H2O, giving a simplified formula of Fe 3+ 3(PO4)2(OH)3·5H2O. Santabarbaraite from both localities was analysed by severaltechniques of X-ray absorption (XANES andEXAFS)and infrared spectroscopy,aswell asDTA,DTG and TG.The results showthat all the Fein santabarbaraiteistrivalent,associated with thepresenceof both H 2O andhydroxyl. Thisisconsistent withan oxidation series from vivianite through metavivianite to santabarbaraite, involving progressive oxidation of Fe 2+ accompanied by conversion of H 2O ligands to OH ions. Such a process leads to a gradual collapse of the vivianite structure as hydrogen bonds are eliminated.Santabarbaraiteistheendproductofthisprocessandcanbethusconsideredthephosphorusanalogueofferrisymplesite.

Crystal Structure and Microtwinning of the New Mineral Clinobarylite BaBe 2 Si 2 O 7

Beryllium is a rare lithophilic element, which is most typical of acidic and alkaline rocks. The number of minerals of this element in the Khibiny–Lovozero complex is rather large. A total of 16 beryllium minerals have already been found in this complex. We discovered a new beryllium barium silicate in pegmatite veins at Yukspor Mountain of the Khibiny massif in the form of colorless, transparent, flattened prismatic crystals (which are often split) up to 2 cm in length. The crystals show perfect cleavage along the (100) plane and less perfect cleavage along the (001) and (101) planes. The mineral is optically biaxial and positive, with N g = 1.705(5); N p = 1.698(3), N m = 1.700(3) , and 2 V = 70(10)° . The chemical composition (wt %), which was determined by local X-ray spectral analysis (the Be content was determined by atomic emission spectral analysis), is as follows: BaO, 47.66; SiO 2 , 36.38 ; BeO, 14.90. The empirical formula (for 7 O atoms) can be written as Ba 1.03 Be 1.97 Si 2.00 O 7.00 . The new mineral is a monoclinic polymorph of orthorhombic barylite BaBe 2 Si 2 O 7 and was recognized as a new mineral type under the name “clinobarylite” by the Commission on New Minerals and Mineral Names of the International Mineralogical Association. Both modifications of BaBe 2 Si 2 O 7 were discovered in differentiates of highly alkaline rocks.

Preparation and identification of anti-transforming growth factor beta1 U1 small nuclear RNA chimeric ribozyme in vitro.

To study the preparation and cleavage activity of anti-transforming growth factor (TGF)beta1 U1 small nuclear (sn) RNA chimeric hammerhead ribozymes in vitro. TGFbeta1 partial gene fragment was cloned into T-vector at the downstream of T7 promoter. (32)p-labeled TGFbeta1 partial transcripts as target RNA were transcribed in vitro and purified by denaturing polyacrylamide gel electrophoresis (PAGE). Anti-TGFbeta1 ribozymes were designed by computer, then synthetic ribozyme fragments were cloned into the U1 ribozyme vector pZeoU1EcoSpe containing U1 snRNA promoter/enhancer and terminator. (32)p-labeled U1 snRNA chimeric ribozyme transcripts were gel-purified, incubated with target-RNAs at different conditions and autoradiographed after running denaturing PAGE. Active U1snRNA chimeric ribozyme (U1Rz803) had the best cleavage activity at 50 degrees; at 37 degrees, it was active, K(m)=34.48 nmol/L, K(cat)=0.14 min(-1); while the point mutant ribozyme U1Rz803(m) had no cleavage activity, so these indicated the design of U1Rz803 was correct. U1Rz803 prepared in this study possessed the perfect specific catalytic cleavage activity. These results indicate U1 snRNA chimeric ribozyme U1Rz803 may suppress the expression of TGFbeta1 in vivo, therefore it may provide a new avenue for the treatment of liver fibrosis in the future.

Crystal structure of new synthetic Ca,Na,Li-carbonate-borate

In the process of studying the phase formation in the Li2CO3-CaO-B2O3-NaCl system, new Ca,Na, Li-carbonate-borate has been synthesized under hydrothermal conditions. The crystal structure of carbonate-borate with the crystallochemical formula Ca4(Ca0.7Na0.3)3(Na0.7□ 0.3)Li5[B 12 t B 10 Δ O36(O,OH)6](CO3)(OH) · (OH,H2O) was refined to R hkl = 0.0716 by the least squares method in the isotropic approximation of atomic thermal vibrations without the preliminary knowledge of the chemical composition and the formula (sp. gr. R3, a rh = 13.05(2) A, α = 40.32(7)]°, V = 838(2) A3, a h = 8.99(2), c h = 35.91(2) A, V = 2513(2) A3, Z = 3, dcalcd = 2.62 g/cm3, Syntex P\(\bar 1\) diffractometer, 3459 reflections, 2θ-θ method, λMo). The structure has a new boron-oxygen radical [B 12 t B 10 Δ O36(O,OH)6] ∞∞ 15− , a double layer of nine-membered [B 6 t B 3 Δ O15(O,OH)3]7.5−-rings bound by BO3-triangles, and twelve-membered [B 6 t B 6 Δ O19.5(O,OH)3]7.5− rings. This allows one to relate this compound to megaborates with complex boron-oxygen radicals. The structure is built from two types of blocks consisting of Ca,Na,B-and Li,B-polyhedra alternating along the c-axis, which explains the perfect cleavage of the crystals along the (0001) plane.

Pararsenolamprite, a new polymorph of native As, from the Mukuno mine, Oita Prefecture, Japan

AbstractPararsenolamprite, the third polymorph of native As, is found at the Mukuno mine, Oita Prefecture, Japan. It is orthorhombic, Pmn21 or P21nm, a = 3.633(2), b = 10.196(2), c= 10.314(2)Å, Z = 18. The seven strongest lines in the X-ray powder diffraction pattern are: 5.17 (100) (002), 4.60 (24) (012), 3.259 (58) (013), 2.840 (27) (032), 2.580 (22) (004), 2.299 (23) (024), and 1.794 (26) (105). Electron microprobe analysis gives As 91.89, Sb 7.25, S 0.48, total 99.62 wt.% (mean of 8), and lead to the empirical formula, As0.96Sb0.03S0.01. It is lead grey in colour and opaque with metallic lustre and black streak. It is sectile and brittle with perfect cleavage on [001]. The VHN25 is 66–91 kg/mm2, corresponding to 2–2.5 in Mohs' hardness scale. The measured and calculated densities are 5.88(5) g/cm3 and 6.01 g/cm3, respectively. In reflected plane-polarized light in air, it is white with a slightly greenish blue tint. Anisotoropy is strong, dark brown to dark greenish grey. Bireflectance is distinct; parallel to elongation it is creamy; perpendicular to elongation it is brown, grey and green. Internal reflections are absent. The reflectance spectra are tabulated in the text.Pararsenolamprite occurs as euhedral crystals in close association with arsenic, stibnite and quartz in a Sb-As-Ag-Au-bearing quartz vein cutting altered Neogene andesite from the Mukuno mine. It forms radial or parallel aggregates of bladed cystals up to 0.8 mm in length.

Fluoro-edenite from Biancavilla (Catania, Sicily, Italy): Crystal chemistry of a new amphibole end-member

Fluoro-edenite, ideally NaCa 2 Mg 5 (Si 7 Al)O 22 F 2 , was found both as prismatic or acicular crystals of millimetric size and as fibers in the rock cavities in gray-red altered benmoreitic lavas occurring at Biancavilla (Etnean Volcanic Complex, Catania, Italy). It is associated with feldspars, quartz, clino- and orthopyroxene, fluoro-apatite, ilmenite, and hematite, and probably crystallized from late-stage hydrothermal fluids. Fluoro-edenite is transparent, intense yellow, non-fluorescent, has vitreous to resinous luster, and gives a yellow streak parallel to the c axis; Mohs’ hardness 5-6, D calc = 3.09 g/cm 3 , perfect cleavage on {110}, and conchoidal fracture. In plane-polarized light, fluoro-edenite is birefringent (1 st order), biaxial negative, α = 1.6058(5), β = 1.6170(5), γ = 1.6245(5), 2V calc = 78.09°, Y ≡ β ⊥ (010), and γ:Z = 26°. No pleochroism is observed. Fluoro-edenite is monoclinic, space group C2/m, a = 9.847(2) Å, b = 18.017(3) Å, c = 5.268(2) Å, β = 104.84(2)°, V = 903.45 Å 3 , Z = 2; the ten strongest X-ray diffraction lines in the powder pattern are [d(I, hkl)]: 3.125(10, 310), 8.403(6,110), 3.271(5,240), 2.807(4,330), 2.703(3,151), 1.894(2,5̄10), 2.938(2,221), 1.649(2, 461), 3.376(2,131), 1.438(2,6̄61). IR analysis showed absorption bands at 1066, 991, 791, 738, 667, 517, 475 cm -1 , and no bands in the OH-stretching region. Structure refinement allowed determination of cation site-preference and ordering. Microprobe analysis of the refined crystal gave SiO 2 52.92, TiO 2 0.29, Al 2 O 3 3.53, FeO t 2.50, MnO 0.46, MgO 22.65, CaO 10.83, Na 2 O 3.20, K 2 O 0.84, F 4.35, Cl 0.07 wt%, and the crystal-chemical formula obtained by combining all the available data is: A (Na 0.56 K 0.15 ) B (Na 0.30 Ca 1.62 Mg 0.03 Mn 0.05 ) C (Mg 4.68 Fe 2+ 0.19 Fe 3+ 0.10 Ti 4+ 0.03 ) T (Si 7.42 Al 0.58 ) O 22 O3 (F 1.98 Cl 0.02 ) 2 .