Celestite Composition,
Crystallization & Structure

Composition. Strontium sulphate, SrSO4 = Sulfur trioxide 43.6, strontia 56.4.

Crystallization. Orthohombic. Crystals resemble closely those of barite (which see). Commonly tabular parallel to the base or prismatic parallel to the brachy or macro-axis with prominent development the domes. Crystals which are elongated parallel to the brachy-axis are frequently terminated in front by four faces in nearly equal development, consisting of 2 prism faces and 2 of the macrodome.

Structure. Crystals. Also radiating fibrous; sometimes granular.

Physical Properties. Perfect cleavage parallel to base and prism. H. = 3.3.5. G. = 3.95-3.97. luster vitreous to pearly. Colorless, white, often faintly blue or red. Transparent to translucent.

Test. Fuses at 3.5-4 and colors the flame crimson (strontium). After ignition gives an alkaline reaction on moistened test pape. Fuset with sodium carbonate and charcoal dust gives a residue, which, when moistened, produces on a clean silver surface a dark stain of silver sulphide. Closely resembles barite and it wil usually need a flame test to positively differentiate the two species.

Occurrence. Celestite is found usually disseminated through limestone or sandstone, or in nest and linig cavities in such rocks. Associated with calcite, dolomite, gypsum, halite sulfur, etc. Notable localities for its occurrence are with the sulfur deposits of Silicy; at Bex, Switzerland; Yate, Gloucestershire, England; Her rengrun, Slovaquia; Strontian Island, Put-in-Bay, Lake Erie; Mineral county, West Virginia; from Lampasas, Texas; Inyo County, California.

Name. Derived from coelestis in allusion to the faint blue color often present.

Use. Used in the preparation of nitrate of strontium for fire works. Other strountium salts used in the refining of sugar.