Sphalerite

Sample of black, tetrahedral euhedral Sphalerite with an adamantine lustre. Slight iridescent on some of the crystal faces. Long, thin colourless euhedral prismatic Quartz crystal embedded on the Sphalerite. Average Sphalerite crystal size: 1.8 cm x 1.5 cm x 1.5 cm. Quartz crystal size: 1.8 cm x 0.3 cm x 0.3 cm. Sphalerite (ZnS) can be yellow, red, black, green, brown, white (rare) or pale grey (Cleiophane) in colour. Lustre can be resinous, adamantine or submetallic and streak is light brown that is always lighter than the colour of the mineral. Hardness is 3 1/2 to 4 and cleavage is perfect in six directions. Sphalerite usually occurs as tetrahedral or dodecahedral crystals with rounded faces but can also be granular, compact or botryoidal.