Sphalerite

Black subhedral tetrahedral Sphalerite crystals that are compacted with an adamantine lustre. Sphalerite (ZnS) can be yellow, brown, red, green, black, white (rare) or pale grey (Cleiophane). Lustre is resinous, adamantine or submetallic. Streak is light brown (always lighter than the mineral) and hardness is 3 1/2 to 4. Cleavage is perfect in six directions. Sphalerite usually occurs as tetrahedral and dodecahedral with rounded faces. Sphalerite can also be cleavage masses, granular, compact or botryoidal.