But because it is so dense and brittle, it is hard to machine ... Fourcroy and N.L. Vauquelin all are said to have found iridium in the acid-insoluble residues of platinum ores.

Iridium oxide exhibits the best available compromise between catalytic activity and stability in acid media, but it is prohibitively expensive for large-scale applications. Therefore, preparing ...

and zinc were studied in boiling 2 M hydrochloric acid, with and without contact with platinum, iridium, rhodium and palladium.