Dolomite and Calcite

Sample of white/pink subhedral Dolomite rhombohedrons with curved faces that is entwined with yellowish to clear rhombohedron Calcite crystals. Dolomite (CaMg(CO3)2) can be white, colourless, pink, grey, green, brown or black with a vitreous or pearly lustre. Streak is white and hardness is 3 1/2 to 4. Cleavage is perfect in three directions, forming a rhombohedron. Dolomite usually occurs as rhombohedral crystals with curved faces or can be granular, compact, massive (Dolomite Rock) or cleavable masses. Calcite (CaCO3) can be white or colourless or various shades of grey, yellow, red, green, blue, brown to black when impure. Lustre can be vitreous or dull and streak is white. Hardness is 3 and cleavage is perfect in three directions forming a rhombohedron. Calcite usually occurs as rhombohedrons but can also be scalenohedron, prism, tabular, acicular, cleavable, granular or compact in form.