Chemical Formula: CaCO3

Chemical Name: Calcium Carbonate

Mineral Class: Carbonate

Mineral Notes: Calcite crystallises in the rhombohedral system. Transparent examples of such crystals are relatively rare and are known as Iceland Spar, after their original country of discovery. Many have the interesting property of double refraction whereby images viewed through the crystal appear twice.  

Description: A thin matrix upon which sit numerous tabular hexagonal crystals of white Calcite. Some of the hexagons are heavily distorted producing a whole range of shapes and forms. Some are twinned or intergrown. The mineral appears to have two distinct types of luster. The flat faces of the crystals are rather waxy, whilst the edhes of the hexagons are very shiny and glassy. Overall, a rare specimen from a classic location.

Location: Charcas, San Louis Potosi, Mexico.