Sphalerite on Dolomite

Dolomite Rock with small yellow subhedral tetrahedral sphalerite crystals with a resinous lustre. Average crystal size: 0.4 cm x 0.4 cm x 0.3 cm. Sphalerite (ZnS) can be yellow, red, green, black, white (rare) or pale grey. Lustre can vary from resinous, adamantine or submetallic and streak is light brown and will always be lighter than the sample. Hardness is 3 1/2 to 4 and cleavage is perfect in six directions. Sphalerite tends to be tetrahedral or dodecahedral with rounded faces and can also be cleavage masses, granular, compact or botryoidal. Dolomite (CaMg(CO3)2) can be white, colourless, pink, grey, green, brown or black. Lustre is vitreous or pearly and streak is white. Hardness is 3 1/2 to 4 and cleavage is perfect in three directions and forms a rhombohedron. Dolomite is commonly rhombohedral with curved faces but can also be granular, massive (Dolomite Rock) or cleavage masses.