Gratonite

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Gratonite
Gratonite-20896.jpg
Gratonite, Excelsior Mine, Cerro de Pasco, Peru, the type locality. 1.7 x 1.6 x 1.5 cm.
General
Category Sulfosalt minerals
Formula
(repeating unit)
Pb9As4S15
Strunz classification 2.JB.55
Crystal system Trigonal
Crystal class Ditrigonal pyramidal (3m)
(same H-M symbol)
Space group R3m

Gratonite is a lead-arsenic sulfosalt mineral, with the chemical composition Pb9As4S15. Gratonite was discovered in 1939 at the Excelsior Mine, Cerro de Pasco, Peru. It is named in honor of geologist L. C. Graton (1880–1970), who had a long-standing association with the Cerro de Pasco mines.

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