title: Gratonite
text: # Gratonite
  
  Gratonite is a lead-arsenic sulfosalt mineral, with the chemical composition $Pb_9As_4S_{15}.$ 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.
  
  