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KOCHSÁNDORITE, A NEW Ca–Al CARBONATE MINERAL SPECIES FROM THE MÁNY COAL DEPOSIT, HUNGARY

István E. Sajó^1, and Sándor Szakáll²

¹ Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59–67, H–1025 Budapest, Hungary
² Department of Mineralogy and Petrology, University of Miskolc, H-3515 Miskolc, Egyetemváros, Hungary

E-mail address: sajo{at}chemres.hu

Kochsándorite, ideally CaAl₂(CO₃)₂(OH)₄·H₂O, is a newly identified mineral species from the Mány coal deposit, north-western Hungary. The mineral occurs as spherical aggregates of colorless acicular crystals up to 0.5 mm long, forming white to pale brown strings in the massive coal. The streak is white, and the crystals have a vitreous to silky luster. The forms, in order of prominence, are: {100}, {110}, {001} and {010}. No cleavage is evident. The mineral is brittle, and its Mohs hardness is about 2–2.5. Optically, the mineral is biaxial (–), 1.597(3), ß not determined, 1.603(6). No pleochroism was observed. Associated minerals at the type locality are quartz, pyrite, böhmite, dolomite, calcite, gibbsite, kaolinite, illite, alumohydrocalcite, gypsum and felsöbányaite. The mineral is orthorhombic, space group Pnma, with the following unit-cell parameters, refined from powder data: a 15.564(6), b 5.591(4), c 9.112(4) Å, V 792.9(3) ų. With Z = 4, the calculated density is 2.514(2) g/cm³, and the measured density is 2.486(20) g/cm³. The mineral dissolves quickly in dilute HCl with effervescence.

Keywords: kochsándorite, new mineral species, carbonate of Ca and Al, Mány coal deposit, Hungary.