Calcite

Colourless/grey two large subhedral rhombohedron crystals of Calcite with a dull lustre. Crystal sizes: 7.0 cm x 4.0 cm x 6.0 cm and 5.0 cm x 4.5 cm x 4.5 cm. Calcite (CaCO3) can be white, colourless or shades of grey, yellow, red, green, blue, brown or black when impure. Lustre is vitreous or dull and streak is white. Hardness is 3 and cleavage is perfect in three directions, forming a rhombohedron. Calcite is usually found as rhombohedrons or scalenohedrons but can also be tabular, acicular, cleavable, granular, compact, stalactitic, oolitic or earthy.