Celestite also known as Celestine, is a strontium sulphate mineral. It’s crystal system is orthorhombic. It’s forms both tabular and prismatic crystals, and Celestite also occurs in massive, fibrous, granular or nodular configurations. It can be colourless, white, grey, blue, green, yellow, orange, reddish or brown. The Celestite most frequently found on the market is a grey-blue variety from Madagascar, which tends to occur in clusters and geodes.