Gratonite

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.