Calcination
The process by which some bodies by the action of fire are reduced to the condition of a calx or cinder. Most of the metals can be reduced to this condition, which renders them easily reducible to powder. By subjecting ores to the action of the fire the volatile parts are driven off, and the water of crystallization dissipated. By this process marble is converted into lime by expelling the carbonic acid and water, and the same may be said of borax, gypsum, alum, and other saline substances which are deprived of their water of crystallization by the process of calcination. There is a difference between calcination and oxidation, fire being a necessary agent in the former case, while metals may be oxidated by acids, heat, or exposure to the atmosphere. See WEATHERING ORES; KILN.
Calcium is a light yellow metal, somewhat harder than lead--very malleable; metals at a red heat and oxidizes in the air. It exists in abundance in limestone, fluor-spar, and gypsum. See LIME.