Chalcocite
Chemical Formula	Cu2S
Species	Sulfides
Crystal System	Monoclinic
Mohs Scale	2-3
Specific Gravity	5.5-5.8
Color	Dark gray to black
Streak	Shiny black to lead gray
Luster	Metallic
Refractive Index	不透明
Diaphaneity	Opaque
Cleavage	Poor/IndistinctIndistinct on
Fracture	Conchoidal
Crystal Habit：Tabular to prismatic crystals also massive to granular