These are larger versions of Peacock Ore Roughs which are chalcopyrite covered in bornite. They are also called peacock as it describes the colours perfectly. This group shows includes some with a dominance of the golden crystals which were not covered by the bornite.
Kids (and more than a few adults) love these naturally brightly colour rocks. Because there is galena in some specimens I do not recommend giving to children under 7.
I originally thought they were coloured, until a prospector showed me Australia’s equivalent peacock ore from Broken Hill.
Wash them to also try and reduce the residue left on your hands. Dimensions of these peacock ore roughs are approximate.