IS 1288 (1982): Methods of test for mineral gypsum. 21/05/1982 This standard prescribes methods of test for mineral gypsum. It covers the methods for determination of fineness, free water, combined water, carbon dioxide, silica and acid insolubles, iron and aluminium oxides, calcium oxides,, magnesinm oxides, sodium chloride, sulphur trioxide, and various forms of .