Platinum sulphide crystal, molecular model. Platinum sulphide (PtS) is found in the mineral cooperite, usually with palladium and nickel ions present as well as platinum. Its unit cell (repeating crystal region, outlined in red) has a tetragonal geometry, with a cube of platinum ions (yellow) having the centre of two faces occupied by a sulphur ion (blue). The next cube adjacent to this cube has the alternate faces occupied by the sulphur ion, which is why the unit cell extends past the boundaries of one cube.