When a crashed ore containing nickel, copper and cobalt is treated with aqueous ammonia . under suitable pressure, ammonia selectively leaches these metals by forming their soluble complexes viz. [Ni(NH3)6]2+ , [Cu(NH3)4]2+ , and [Co(NH3)5H2O]3+ respectively from the ore leaving behind the gangue, iron(III) oxides/hydroxides and aluminosilicate.