Calcite, (w. Cuprite inclusions)

Mineral: Calcite, Cuprite, Quartz
Chemistry: CaCO3
Size: 89 mm
Owner: Mariusz Oleszczuk
Photographer: Mariusz Oleszczuk

A plate of intergrown calcite rhombs (to 13 mm), with a few small quartz crystals in association.  Both minerals are included and coloured, to varying degrees, by microscopic inclusions of cuprite (var. chalcotrichite).

The distribution of cuprite inclusions in the calcite is zoned; one or two cleaved surfaces indicate that the cores of the calcite are essentially inclusion-free, but that an outer zone of inclusions is present which imparts a yellow, orange, or even red colour depending on the concentration of the inclusions and, possibly, on the particle size.