CELESTINE or CELESTITE, a name applied to native strontium sulphate (SrSO,), having been suggested by the celestial blue colour which it occasionally presents. It is usually colourless, or has only a delicate shade of blue. It crystallizes in the ortho rhombic system, being isomorphous with barytes (q.v.). The cleavage is a perfect parallel to the basal pinacoid, and a less marked parallel to the prism. Although celestine much resembles barytes in its physical properties, having for example the same hardness (3), it is less dense, its specific gravity being 3.9. It is less abundant than barytes, but is, however, much more soluble.
Celestine occurs in the Triassic rocks of Britain, especially in veins and geodes in the Keuper marl in the neighbourhood of Bris tol. At Wickwar and Yate in Gloucestershire it is worked for in dustrial purposes. Colourless crystals of great beauty occur in as sociation with calcite and native sulphur in the sulphur deposits of Sicily, as at Girgenti. Very large tabular crystals are found in limestone on Strontian island in Lake Erie ; and a blue fibrous va riety from near Frankstown, Blair county, Pa., is notable as hav ing been the original celestine on which the species was founded by A. G. Werner in 1798.
Celestine is much used for the preparation of strontium hydrate, which is employed in refining beetroot sugar. (F. W. R.)