Calcite Minerals By Silicon Products (P) Associates

CHEMICAL COMPOSITION CaCO3 Small quantities of magnesium, iron, manganese, zinc and lead may be present replacing the calcium.

PHYSICAL CHARACTERS: It is colourless or white, some times with grey, yellow, blue and red tints. It has vitreous to earthy luster. It can be Scratched by knife, hardness-3 and specific gravity is 2.7 it shows conchoidal fracture and is in fusible, becoming highly luminous when heated it gives effervescence with evolution of carbon dioxide in cold dilute acid.

SPECIFICATION: (a)Optical Use: Should Have Perfect Crystalline Structure and transparency. The crystal must be at least 2.54 cm (one inch) long by 1.27 cm thick. It should be colourless and free form cloudy inclusions, cavities or foreign substances "lceland spar " is greatly valued in optical industry for the manufacture of Nicol prism. (b) Calcite/Aragonite: IS 918-1968