Search

New discoveries of kuksite, [Pb.sub.3][Zn.sub.3][Te.sup.6+][P.sub.2][O.sub.14], from the Black Pine mine, Montana, and Blue Bell claims, California, have enabled a detailed crystal-chemical study of the mineral to be undertaken. Single-crystal X-ray structure refinements of the structure indicate that it is isostructural with dugganite, [Pb.sub.3][Zn.sub.3][Te.sup.6+][As.sub.2][O.sub.14], and joelbruggerite, [Pb.sub.3][Zn.sub.3]([Sb.sup.5+],[Te.sup.6+])[As.sub.2][O.sub.13](OH,O). Kuksite from the Black Pine mine crystallizes in space group P321, with unit-cell dimensions a = 8.392(1), c = 5.204(1) [Angstrom], V = 317.39(8) [[Angstrom].sup.3], and Z = 1 ([R.sub.1] = 2.91% for 588 reflections [[F.sub.o] > 4[sigma]F] and 3.27% for all 624 reflections), while Blue Bell kuksite has the unit cell a 8.3942(5), c = 5.1847(4) [Angstrom], and V = 316.38(4) [[Angstrom].sup.3] ([R.sub.1] = 3.33% for 443 reflections [[F.sub.o] > 4[sigma]F] and 3.73% for all 483 reflections). Chemical analyses indicate that solid-solution series exist between kuksite, dugganite, and joelbruggerite. Raman spectroscopic and powder X-ray diffraction data are also presented for samples from both occurrences. The crystal structure of the chemically related species yafsoanite, [(Ca,Pb).sub.3][Te.sup.6+.sub.2][Zn.sub.3][O.sub.12], from the type locality (Delbe orebody, Kuranakh Au Deposit, Aldan Shield, Saha Republic, Russia), has been refined to [R.sub.1] = 2.41% for 135 reflections [[F.sub.o] > 4[sigma]F] and 3.68% for all 193 reflections. A garnet-type structure has been confirmed and significantly improves upon the results of an earlier structure determination. Keywords: Kuksite, dugganite, joelbruggerite, Black Pine, Blue Bell, tellurate, yafsoanite, Delbe orebody, crystal structure DOI: 10.2138/am.2010.3483

Kapundaite, ideally [(Na,Ca).sub.2][Fe.sup.3+.sub.4][(P[O.sub.4]).sub.4] [(OH).sub.3] x 5[H.sub.2]O, is a new mineral (IMA2009-047) from Toms phosphate quarry, Kapunda, South Australia, Australia. The new mineral occurs as cavernous aggregates of fibers up to several centimeters across, associated with leucophosphite, natrodufrenite, and meurigite-Na crystals and amorphous brown, black, and/or greenish coatings. Individual kapundaite crystals are very thin flattened fibers up to a few millimeters in length, but typically no more than a few micrometers in thickness. The main form observed is {100}; other forms in the [010] zone are present, but cannot be measured. Crystals of kapundaite are pale to golden yellow, transparent to translucent, have a yellow streak and silky luster, and are non-fluorescent. Mohs hardness is estimated to be about 3; no twinning or cleavage was observed. Kapundaite is biaxial (+), with indices of refraction [alpha] = 1.717(3), [beta] = 1.737(3), and [gamma] = 1.790(3). 2V could not be measured; [2V.sub.cale] is 64.7[degrees]. The optical orientation is Z = b, Y [approximately equal to] c with weak pleochroism: X= nearly colorless, Y= light brown, Z = pale brown; absorption: Y> Z > X. No dispersion was observed. The empirical chemical formula (mean of seven electron microprobe analyses) calculated on the basis of 24 O is ([Ca.sub.1.13][Na.sub.0.95])[summation]2.08[([Fe.sup.3+.sub.3.83] [Mn.sub.0.03][Al.sub.0.02][Mg.sub.0.01]).sub.[summation]3.89] [P.sub.3.92][O.sub.16]([OH).sub.3] x 5[H.sub.2.11]O. Kapundaite is triclinic, space group P[bar.1], a = 6.317(5), b - 7.698(6), c = 9.768(7) [Angstrom], [alpha] = 105.53[(1).sup.o], [beta] = 99.24[(2).sup.o], [gamma] = 90.09[(2).sub.o], V = 451.2(6) [[Angstrom].sup.3], and Z- 1. The five strongest lines in the powder X-ray diffraction pattern are [[d.sub.obs] in [Angstrom], (I) (hkl)]: 9.338 (100) (001 ), 2.753 (64) (2[bar.1]1), 5.173 (52) (011 ), 2.417 (48) ([bar.2][bar.1]-3, 202, 0[bar.1]4), and 3.828 (45)(0[bar.2]1). The crystal structure was solved from single-crystal X-ray diffraction data using synchrotron radiation and refined to [R.sub.1] = 0.1382 on the basis of 816 unique reflections with [F.sub.o] > 4[sigma]F. The structure of kapundaite is based on a unique corrugated octahedral-tetrahedral sheet, which is composed of two types of chains parallel to a. Kapundaite is structurally related to melonjosephite. The mineral is named for the nearest town to the quarry. Keywords: Kapundaite, new mineral, phosphate, Toms phosphate quarry, crystal structure, octahedral-tetrahedral sheet, melonjosephite DOI: 10.2138/am.2010.3466

Most carbon on Earth is bound within minerals, and increasing the uptake of atmospheric carbon dioxide into minerals may reduce the greenhouse gas content of the atmosphere. We document carbon disposal through the mineralization of mine tailings at Clinton Creek, Yukon Territory, and Cassiar, British Columbia. We confirm crystallographic binding of carbon in these tailings and quantify carbon dioxide uptake using quantitative phase analysis with the Rietveld method for X-ray powder diffraction data. Planar disorder in the structures of the kaolinite-serpentine group minerals makes Rietveld refinements of X-ray powder diffraction data for serpentinites problematic. Using structureless pattern fitting and with the addition of a known quantity of a well-crystallized material, the problem of structural disorder is overcome by considering the serpentine minerals as amorphous phases. We test the accuracy and precision of this refinement method using synthetic serpentine-rich mine tailings of known composition. Estimates of the abundance of hydrated magnesium carbonates in these tailings have a precision of approximately 5% relative for mineral species present in amounts greater than 10 wt%. Precise estimates of carbonate mineral content and crystallographically bound atmospheric C[O.sub.2] are made for samples of serpentine-rich tailings from Clinton Creek and Cassiar. Results for mine tailings are also compared to mineralogically similar samples from a carbonate playa at Atlin, British Columbia. The potential for decomposition of metastable hydrated magnesium carbonate phases to geologically stable magnesite may represent long-term stability of the products of mineral sequestration in mine tailings. Keywords: Carbon disposal, mineral sequestration, quantitative phase analysis, Rietveld method, Pawley method, X-ray powder diffraction, serpentinite, mine tailings, carbonation, order-disorder

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([Mg.sub.3-x][Al.sub.x] [[Al.sub.1+x][Si.sub.3-x][O.sub.10]] [(OH).sub.y][(F).sub.2-y] between 0.0 [less than or equal to] x [less than or equal to] 0.8 and 0.5 [less than or equal to] y [less than or equal to] 1.8, was studied by [sup.27]Al MAS, MQMAS, {[sup.1]H/[sup.19]F} [vector] [sup.27]Al 2D CPMAS (HETCOR) and {[sup.1]H/[sup.19]F} [sup.27]Al REDOR solid-state NMR an 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. Signais from the different phases can be separated in the [sup.27]Al MQMAS NMR spectra by generation of an isotropic dimension in F1. The [sup.27]Al quadrupolar parameters of the four phases were estimated from [sup.27]Al 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 [sup.IV]Al site in phlogopite. The [sup.VI]Al site shows a clear increase of the asymmetry parameter and [C.sub.Q] with increasing F content. The estimated [sup.27]Al signal areas show the lowest amount of impurity phases at high OH contents and a stabilization of [sup.VI]Al sites by hydroxyl groups. The {[sup.1]H} [vector] [sup.27]Al 2D CPMAS (HETCOR) NMR experiment at short contact rimes provides information about site neighborhoods of tetrahedral Al sites and [Mg.sub.3]OH as well as [Mg.sub.2]AlOH sites, whereas magnetization is only transferred to the octahedral Al sites from hydroxyl groups in [Mg.sub.2]AlOH sites. The {[sup.1]H/[sup.19]F} [vector] [sup.27]Al 2D CPMAS (HETCOR) NMR spectrum is dominated by [sup.IV]Al sites coupled to the [Mg.sub.3]F complex in phlogopite. Resonances from [Mg.sub.2]AlF complexes are not observed. Finally, the {[sup.1]H/[sup.19]F} [sup.27]Al REDOR experiments support the results of the 2D CPMAS (HETCOR) experiments.

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([Mg.sub.3-x][Al.sub.x])([Al.sub.1+x][Si.sub.3 -x][O.sub.10])[(OH).sub.y] [(F).sub.2-y] (0.0 [less than or equal to] x [less than or equal to] 0.8 and 0.5 [less than or equal to] y [less than or equal to] 1.8) were studied using [sup.29]Si, [sup.1]H, and [sup.19]F 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 ([alpha]-[Al.sub.2][O.sub.3]), kalsilite (KalSi[O.sub.4]), and potassium aluminum hexafluoride ([K.sub.3]Al[F.sub.6]*0.5[H.sub.2]O)] were clearly identified by powder X-ray diffraction and electron-probe microanalysis. For phlogopite, the unit-cell parameters [a.sub.0] and [b.sub.0] decrease whereas [c.sub.0] increases with increasing Al-content (x). The average crystal size of phlogopite is about 1-2 [micro]m. The [sup.29]Si MAS NMR spectra show up to four resonances at approximately -91, -87, -83, and -80 ppm, which can be assigned as [Q.sup.3](n Al) signals with n = 0-3. The ideal [Si/.sup.IV] Al 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 [sup.1]H and [sup.19]F MAS NMR spectra. The [sup.1]H MAS NMR spectra show a water signal at 4.7 ppm, a signal due to [Mg.sub.2]AlOH at 1.8 ppm, and a signal due to [Mg.sub.3]OH at 0.7 ppm. The [sup.19]F MAS NMR spectra exhibit a signal for [Mg.sub.2]AlF at -150 ppm, one due to Al[F.sub.6] ([K.sub.3]Al[F.sub.6]*0.5[H.sub.2]O) at -157 ppm, and one for [Mg.sub.3]F at -174 ppm. Comparison of the [sup.1]H and [sub.19]F 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.

Amphiboles were synthesized at 750 [degrees] C, 1 kbar ([H.sub.2]O) for compositions at 20% intervals along the join potassium-richterite-tremolite. Structural variations, site occupancies, and modal analyses of the experimental products (amphibole + minor diopside, quartz, and enstatite) were characterized by Rietveld structure refinement, with final [R.sub.Bragg] indices in the range 4-6%, and by infrared spectroscopy in the principal OH-stretching region. Amphibole compositions were determined by (1) site-scattering refinement for the A and M4 sites that are occupied by (K, [square]) ([square] = vacancy) and (Na,Ca), respectively; and (2) mass-balance calculations involving the modal analysis and the nominal experimental product composition. These measurements agree within 1% absolute and show close agreement with electron-microprobe compositions for the two samples that we could analyze. Deviations from nominal amphibole composition are up to 19% absolute. The resulting relations between cell dimension and composition are linear. The major change in cell dimensions is a decrease of 0.25 [Angstrom] in a with increasing tremolite component. The infrared spectra show two principal peaks at 3735 and 3675 [cm.sup.-1], corresponding to the local arrangements MgMgMg-OH-AK (the Kr band) and MgMgMg-OH-A[square] (the Tr band), respectively. The relative variation in peak intensity as a function of amphibole composition shows that the molar absorptivities of the two bands are significantly different. The ratio of the molar absorptivities for the two bands is 2.2.

Amphiboles were synthesized at 750 [degrees] C, 1 kbar ([H.sub.2]O) on the binary joins (nickel, magnesium)-richterite and (magnesium, cobalt)-richterite. Structural variations and site occupancies were characterized by Rietveld structure refinement, with final [R.sub.Bragg] indices in the range 4-9%, and by powder infrared spectroscopy in the principal OH-stretching region. Site-occupancy refinement of Ni-Mg and Mg-Co distributions give the partition coefficients over M1,3 and M2 where [K.sup.M2+] = [([M.sup.2+]/Mg).sub.M1,3]/[([M.sup.2+]/Mg).sub.M2], and [M.sup.2+] = [Ni.sup.2+] or [Co.sup.2+], [Mathematical Expression Omitted] and [Mathematical Expression Omitted]. Both [K.sub.d] values are greater than 1.0, whereas [6]r([Ni.sup.2+]) < [6]r(Mg) < [6]r([Co.sup.2+]); this indicates that cation size is not the primary factor affecting the ordering of Ni-Mg and Mg-Co over the octahedral sites. The infrared spectra of intermediate binary compositions show fine structure caused by ordering of Ni-Mg or Mg-Co over the M1,3 sites and by ordering of Na and [square] (vacancy) at the A site; thus intermediate compositions show an eight-band spectrum in the principal OH-stretching region. Precise band intensities were derived by nonlinear least-squares fitting of Gaussian band shapes to the observed spectra. The relative observed intensities of the combinations of bands [Mathematical Expression Omitted] and [Mathematical Expression Omitted] are in accord with the equations of Burns and Strens (1966), indicating that there is no significant variation in molar absorptivity with frequency (energy) for individual bands within a single sample (spectrum). Combined with the results of Skogby and Rossman (1991) on polarized single-crystal infrared spectra of amphiboles, this result suggests that different local configurations of M1,3 cations in amphiboles couple such that the transition probabilities of the associated OH groups are equal.

The Silvana mine has produced an array of very fine to spectacular micromineral and thumbnail specimens including rare, fiery-orange pyrostilpnite, lustrous cubanite, pyrargyrite and stephanite as well as showy, irridescent [...]

The Engineer mine is a Dana locality for classic, botryoidal 'allemontite' (stibarsen and native arsenic). Several other minerals of interest to the collector are also found, including crystallized auriferous silver [...]

The Rietveld structure refinement of amphiboles which are prepared along with the K(NaCa)Mg5(SiTi)O22(OH,F)2 from the (OH)2 to F2 atoms per formula unit (ap fu) indicates that the positively ionized Ti is fully ordered at the T2 site. The single-phase amphibole with 0.6 ap fu of titanium is determined for the OH end-member beginning composition. The complex amphibole-priderite-titanite-rutile, produced along the OH-F, joins with a reduction in the end-member fluor-richterite to 0.16 ap fu. A primary band for the titanium-rich OH-end member located at 3728 lines per centimeter is found in the infrared spectra of the principal OH-stretching region.

The synthesis and characterization of potassium richterite containing variable amounts of Nickel, Magnesium and Cobalt in octahedral strips is a result of the hydrothermal syntheses. For all compositions in the system, the monophase amplibole products were obtained at 750 degree C, 1kbar (H2O). The variations in structure and site occupancies were marked by Rietveld structure refinement, with final R (Bragg) indices ranging from 2-4%. The individual cell dimensions along the Ni-Mg-Co revealed a break at the Mg composition, suggesting that constituent cation sizes determine the cell volume and grand mean (M-O) bend length, and not the substituent cations.

A study was conducted on structural variations occurring in nickel aluminate spinel. Results showed that under elevated temperatures the a cell edge increased and the spinel's cation distribution became more random. Further observations also showed that structural reequilibration occurred during quenching. The results obtained from the study differed significantly from a previous study of nickel aluminate spinel.

A simple method to produce white light from sol-gel matrices, such as SiO2 and ZrO2, made with Ln(super 3+)-doped LaF3 nanoparticles co-doped with Yb(super 3+) ions is reported. Similar to SiO2 matrix, white light is observed with CIE coordinates of 0.37 and 0.31 when ZrO2 films are made with the Yb(super 3+)/Eu(super 3+), Yb(super 3+)/Er(super 3+), and Yb(super 3+)/Tm(super 3+) nanoparticles.

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, [sup.1]H, [sup.6]Li, [sup.7]Li, [sup.133]Cs, [sup.27]Al, [sup.29]Si MAS, and {[sup.1]H} [sup.13]C CPMAS NMR and Rietveld structure refinement. [sup.29]Si MAS NMR and [sup.27]Al MAS NMR spectroscopy show a framework with strong alternating order of the Si[O.sub.4] and Al[O.sub.4] tetrahedra and an Si/Al ratio of one. [sup.6]Li MAS NMR suggests the existence of two different signals that cannot be resolved in the [sup.7]Li MAS NMR spectrum. [sup.133]Cs 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 [Epsilon]-cages; Li ions are located in the channels and are coordinated by water molecules.