GOLD EXHIBITS HACKLY FRACTURE, IS MALLEABLE, IN NON-MAGNETIC DUE TO ITS LACK OF IRON, AND OCCURS AS VEINS OR NUGGETS. PYRITE: DISULFIDE OF IRON WITH A SUBSTANTIAL AMOUNT OF NICKEL AND COBALT. GOLD: AU; PYRITE EXHIBITS CONCHOIDAL FRACTURE, IS NOT MALLEABLE, IS MAGNETIC DUE TO ITS PRIMARY CONSTITUENT BEING IRON, AND OCCURS IN A CUBIC FORM.