Galenite and quartz crystals. Sample of galenite (galena, grey) with quartz (white) crystals growing on it. Galenite is a lead sulphide and is the most important ore of lead. It occurs as a mass of dense, dark grey or glossy crystals and is one of the most abundant and widely distributed sulphide minerals. Galenite is a semiconductor and was used in early wireless communication systems as the crystal in crystal radio sets.