Langite
Chemical Formula	Cu4(SO4)(OH)6·2H2O
Species	Sulfates
Crystal System	Monoclinic
Mohs Scale	2-3
Specific Gravity	2.28-3.34
Color	Greenish blue, sky-blue to bluish green
Streak	Blue green
Luster	Vitreous, Silky
Refractive Index	n = 1.708 n = 1.760 n = 1.798
Diaphaneity	Translucent
Cleavage	Distinct/GoodOn and .
Fracture	Uneven
Crystal Habit：Crystals scaly, or as crusts; earthy