Description | The gray semimetallic material is bismuthinite, the gold material is chalcopyrite. Bismuthinite (bismuth sulfide, Bi2S3) is an important ore of bismuth. The specimens shown, which are up to 2 cm across, look similar to stibnite (antimony sulfide, Sb2S3). It is difficult to distinguish the two minerals. However, bismuthinite is heavier than stibnite and well formed crystals of bismuthinite have straighter, flatter faces. |