Calcite

This sample is a Calcite vein within a sandstone that shows subhedral scalenohedron crystals and is colourless. Lustre is vitreous. Calcite (CaCO3) can be white, colourless or pale shades of grey, yellow, red, green, blue or brown and black if there are impurities. Lustre can be vitreous or dull and streak is white. Hardness is 3 and cleavage is perfect in three directions and forms a rhombohedron. Calcite is usually rhombohedron or scalenohedron but can also be tabular, acicular, cleavable, granular, compact, stalactitic, oolitic or earthy in form.