Abstract
Kapundaite, ideally (Na,Ca)2Fe43+(PO4)4(OH)3∙5H2O, 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 α = 1.717(3), β = 1.737(3), and γ = 1.790(3). 2V could not be measured; 2Vcalc is 64.7°. The optical orientation is Z = b, Y ≈ 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 (Ca1.13Na0.95)Σ2.08(Fe3+ 3.83Mn0.03Al0.02Mg0.01)Σ3.89P3.92O16(OH)3·5H2.11O. Kapundaite is triclinic, space group P1, a = 6.317(5), b = 7.698(6), c = 9.768(7) Å, α = 105.53(1)°, β = 99.24(2)°, γ = 90.09(2)°, V = 451.2(6) Å3, and Z = 1. The five strongest lines in the powder X-ray diffraction pattern are [dobs in Å (I) (hkl)]: 9.338 (100) (001), 2.753 (64) (21̄1), 5.173 (52) (011), 2.417 (48) (2̄1̄3, 202, 01̄4), and 3.828 (45) (02̄1). The crystal structure was solved from single-crystal X-ray diffraction data using synchrotron radiation and refined to R1 = 0.1382 on the basis of 816 unique reflections with Fo > 4σF. 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 mélonjosephite. The mineral is named for the nearest town to the quarry.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- TEM-assisted dynamic scanning force microscope imaging of (001) antigorite: Surfaces and steps on a modulated silicate
- PH₂O-dependent structural phase transitions in the zeolite mesolite: Real- and reciprocal-space crystal structure refinements
- The crystal structure of esperite, with a revised chemical formula, PbCa2(ZnSiO4)3, isostructural with beryllonite
- Dendritic zircon formation by deterministic volume-filling fractal growth: Implications for the mechanisms of branch formation in dendrites
- Enthalpies of formation of pyrrhotite Fe1–0.125xS (0 ≤ x ≤ 1) solid solutions
- Crystal chemistry of synthetic lawsonite solid-solution series CaAl2[(OH)2/Si2O7]·H2O– SrAl2[(OH)2/Si2O7]·H2O and the Cmcm–P21/m phase transition
- Coulsellite, CaNa3AlMg3F14, a rhombohedral pyrochlore with 1:3 ordering in both A and B sites, from the Cleveland Mine, Tasmania, Australia
- Synthesis and characterization of zeolite 4A-type desiccant from kaolin
- Effect of iron on the compressibility of hydrous ringwoodite
- Kapundaite, (Na,Ca)2Fe4 3+(PO4)4(OH)3·5H2O, a new phosphate species from Toms quarry, South Australia: Description and structural relationship to mélonjosephite
- Rate of antigorite dehydration at 2 GPa applied to subduction zones
- IR absorption coefficients for water in nominally anhydrous high-pressure minerals
- Experimental techniques for determining tin solubility in silicate melts using silica capsules in 1 atm furnaces and rhenium capsules in the piston cylinder
- Cassiterite-saturated minimum melting behavior within Sn-SnO2-SiO2 at 1 atm and 10 kbar
- Cr-bearing tourmaline associated with emerald deposits from Swat, NW Pakistan: Genesis and its exploration significance
- Mechanism and kinetics of reduction of a FeO-Fe2O3-CaO-MgO aluminosilicate melt in a high-CO-activity environment
- Biodurability of chrysotile and tremolite asbestos in simulated lung and gastric fluids
- High-pressure behavior of Ca/Na clinopyroxenes: The effect of divalent and trivalent 3d-transition elements
- Uvarovite from chromite-bearing ultramafic intrusives, Orissa, India, a crystal-chemical characterization using 57Fe Mössbauer spectroscopy
- An X-ray Rietveld and infrared spectral study of the Na2(Mn1–xM2+x )Fe2+Fe3+(PO4)3 (x = 0 to 1 and M2+ = Mg, Cd) alluaudite-type solid solutions
- Dissolution kinetics of anorthite in a supercritical CO2–water system
- Evaluation of the elasticity normal to the basal plane of non-expandable 2:1 phyllosilicate minerals by nanoindentation
- 57Fe Mössbauer spectroscopy and electrical resistivity studies on naturally occurring native iron under high pressures up to 9.1 GPa
- Letter. Discreditation of paraspurrite
- Letter. High-pressure magnetic transition in hcp-Fe
- Letter. Reduced As components in highly oxidized environments: Evidence from full spectral XANES imaging using the Maia massively parallel detector
- Letter. FTIR spectroscopy with a focal plane array detector: A novel tool to monitor the spatial OH-defect distribution in single crystals applied to synthetic enstatite
- Letter. Akaogiite: An ultra-dense polymorph of TiO2 with the baddeleyite-type structure, in shocked garnet gneiss from the Ries Crater, Germany