Steacyite

Steacyite

Steacyite
General
Category Cyclosilicate
Formula
(repeating unit)
Kvariable(Ca,Na)2(Th,U)Si8O20
Strunz classification 9.CH.10
Crystal system Tetragonal
Crystal class Ditetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space group P4/mcc
Identification
Color Gray, dark brown, green, beige
Mohs scale hardness 5
Luster Vitreous, greasy, dull
Diaphaneity Translucent, opaque

Steacyite is a complex silicate mineral containing thorium and uranium; formula Kvariable(Ca,Na)2(Th,U)Si8O20. It forms small brown or yellow green crystals, often cruciform twinned crystals. It is radioactive. It was discovered at Mont-Saint-Hilaire, Quebec in 1982 and is named after Harold Robert Steacy (1923–2012), mineralogist.[1]

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