Dear Sir or Madam, We are one of the biggest pyrite products manufacturer in China.Our main products are high quality ferro sulphur/pyrite/FeS2 lumps and its powder .It is used in glass industry for the making of brown glass.The quality and the size as follows: Pyrite powder(FeS2): Quality : S 48%min; Fe 43%min; H2O 1%max. Size:100mesh X down;200mesh 90% down;325mesh 90%min down;