Galena. Credit: Mineral Information Institute.
Galena forms cubic crystals.
Galena is a gray, brittle mineral, essentially lead (II) sulfide (PbS), the principal ore of lead. It forms cubic or octahedral crystals, and also occurs as granular masses. Deposits of galena, also called "lead glance," have been worked worldwide for their lead. Galena is found especially in hydrothermal veins and as a replacement for limestone and dolomite rocks. Silver is often found in appreciable amounts in galena. Hardness 2.5–2.7, relative density 7.5.