Galena is an important lead mineral that contains PbS. Its lead content is 86.8%, and it has an isometric crystal structure. Its crystals can be cubic, octahedral or sub-octahedral. Some appear as blocky, granular and fibrous aggregates. The colour and streaks are lead-grey. It has opaque diaphaneity, a metallic lustre, a specific gravity of 7.58, a Mohs hardness of 2.5 and sub-conchoidal fractures. Hydrothermal galena veins usually form when hot fluids rise to the upper crust. Galena often forms with fluorite, quartz, calcite, sphalerite and pyrite. Both galena ore and galena crystal clusters can be crafted into ornamental stones.