User:Tillman/Gratonite



Gratonite is a lead-arsenic sulfide 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 Cerro de Pasco.