Calcite, (w. Hematite and Malachite)

Chemistry: CaCO3
Size: 100 mm.
Owner: Geoff Krasnov
Photographer: Geoff Krasnov

Composite rhombohedral calcite crystals (to 70 mm), coloured brick-red by minute inclusions of iron oxide, probably hematite (?). The calcite rests on a sliver of similarly-coloured matrix, with minor malachite providing an attractive colour contrast.