An
octahedral crystal of Galena with its corners truncated by the cubic form.
The crystal is perched on a piece of the Boone Chert from Joplin Missouri.
These unusual crystals of Galena are very much flatted and display the spinel twin
law. This specimen is from Russia.
Galena has very good cubic
cleavage. Even the smallest fragments show this cubic tendency.
CHEMISTRY PbS Lead sulfide
CRYSTALLOGRAPHY Isometric (Cubic)
CRYSTAL GROWTH AND HABITS Galena is most commonly found as cubes but it also forms cubes that have modifications produced by the octahedron, dodecahedron or rarely the trisoctahedron. Galena can also be granular to massive.
COLOR AND OTHER OPTICAL PROPERTIES Bright silvery to dull lead gray
HARDNESS 2.5
SPECIFIC GRAVITY 7.4 - 7.6
LUSTER Bright metallic
STREAK Lead gray
BREAKABILITY Perfect cubic cleavage, brittle
OCCURRENCE Galena is commonly found in metallic sulfide veins.
ASSOCIATED MINERALS Sphalerite, Pyrite, Marcasite, Chalcopyrite, Cerussite, Anglesite, Dolomite, Quartz, Calcite, Fluorite