Calcite on Dolomite and Pyrite

Sample of colourless-yellow subhedral prismatic Calcite embedded on black rhombohedral euhedral Dolomite with curved faces and small cubic euhedral Pyrite. Average Calcite crystal size: 2.2 cm x 1.7 cm x 1.0 cm. Largest Dolomite crystal size: 0.6 cm x 0.4 cm x 0.1 cm. Calcite (CaCO3) can be white, colourless or pale shades of grey, yellow, red, green, blue or brown and 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 usually occurs as rhombohedrons, scalenohedrons and prisms. Calcite can also be tabular, acicular, cleavable, granular, compact, stalactitic, oolitic or earthy. 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, forming a rhombohedron. Dolomite usually occurs as rhombohedral crystals with curved faces but can also be granular, compact, massive (Dolomite Rock) and cleavage masses. Pyrite (FeS2) can be pale yellow or brass-yellow that is often tarnished with brown film or iridescent. Lustre is metallic and streak is greenish black. Hardness is 6 to 6 1/2. Pyrite usually occurs as cubes or pyritohedrons with parallels striations along the crystal faces. Pyrite can also occur as octahedrons, nodules, fine to coarse granular or fibrous.