 One suitable method for purification for the raw platinum , which contains platinum , gold , and the other platinum @-@ group metals , is to process it with aqua regia , in which palladium , gold and platinum are dissolved , whereas osmium , iridium , ruthenium and rhodium stay unreacted . The gold is precipitated by the addition of iron ( II ) chloride and after filtering off the gold , the platinum is precipitated as ammonium chloroplatinate by the addition of ammonium chloride . Ammonium chloroplatinate can be converted to platinum by heating . <unk> hexachloroplatinate ( IV ) may be reduced with elemental zinc , and a similar method is suitable for small scale recovery of platinum from laboratory residues . 
