Calcite

[Sarah]

Calcium carbonate, or carbonate of lime. It is rhombohedral inits crystallization, and thus distinguished from aragonite. Itincludes common limestone, chalk, and marble. Called also calc-sparand calcareous spar.

[Monty]

A white or colourless mineral consisting of calcium carbonate. It is a major constituent of sedimentary rocks such as limestone and is deposited in caves to form stalactites and stalagmites.