A sample of the mineral celestite (strontium sulphate). A common mineral forming prismatic or more rarely tabular crystals,which are colourless,milky white,pale blue or yellow. It is often found disseminated in carbonate-rich rocks or evaporite deposits,associated with minerals such as gypsum,aragonite & sulphur,and chlorides. Celestite is the main ore for strontium and its salts,and is used in making fireworks and flares (giving a crimson flame). It is also used in the nuclear industry,paint and electrical batteries,in the refining of beet sugar,and in the preparation of iridescent glass and porcelain |