Calcite, (w. Duftite)

Mineral: Calcite, Duftite
Chemistry: CaCO3
Size: 58 mm
Owner: Jim Robison
Photographer: Crystal Classics

A group of colourless to white rhombohedral calcite crystals (to 40 mm) is included and partly overgrown with bright green microcrystals of duftite (?).

The inclusions of duftite (?) are restricted to the outer zones of the calcite rhombs, indicating a late change in solution chemistry that allowed crystallisation of the duftite (?) on the still-growing calcite surfaces.  Both minerals continued to form, resulting in the zones of near-surface inclusions and a final partial encrustation of duftite (?) on the calcite surface.

Although the duftite (?) has not been verified for this particular specimen, this is a classic association from Tsumeb.