Calcium
Ca
atomic number
20
melting point
842°C

1. When exposed to the blowpipe flame, some calcium-bearing minerals (i.e. calcite) impart a yellowish-red color to the flame; the effect is usually enhanced if the sample is moistened with HCl before ignition.

2. Dissolve the powdered mineral in a dilute HCl solution, then add a few drops of dilute H2SO4; a white precipitate composed of CaSO4 • 2H2O will form; the composition of the precipitate is confirmed if the addition of water followed by boiling dissolves the precipitate.

3. Intensely heat the powdered mineral sample, then touch the sample to a piece of moistened turmeric paper; an alkaline reaction will be produced; (the calcium carbonates and sulfates all test alkaline in this procedure).