Calcite, (on Dolomite)

Mineral: Calcite, Dolomite
Chemistry: CaCO3
Size: 85 mm.
Owner: Geoff Krasnov
Photographer: Geoff Krasnov

Colourless to pale cream-coloured rhombs of calcite (to 35 mm) set on a pinkish-brown "shell" of crystallised dolomite. The calcite rhombs have nearly opaque cream-coloured cores, but are gemmy, transparent and colourless  at the margins.

The reverse of the specimen (Photograph 2) shows that the dolomite appears to have formed as platy layers of crystallites, initially epimorphous perhaps, over a druse of calcite (?) crystals that have subsequently dissolved away. The edges of the specimen show that the dolomite is multi-layered with a distinct colour banding.  Notably, the concave face of the dolomite (Photograph 2) has an unusual lilac colour.