Celestine is a mineral with a hardness of 4 out of 10 on the Mohs scale of mineral hardness [?]. These Orthorhomibicly structured gems are made of strontium sulfate, their full chemical compound being SrSO4.

Celestine appears as colorless, or pale blue, and is transparent to translucent, and has two directions of cleavage. It is very brittle, and has a vitreous to pearly luster.

It occurs in sediments associated with sulfur, with evaporate minerals like gypsum, anhydrite, and halite; in hydrothermal veins with galena and sphalerite; as concretions in clay and marl; in cavities in basic lavas, and in the cap-rock of salt domes.

It is insoluble in acids, but slightly soluble in water, and may fluoresce under ultraviolet light. When heated, it fuses easily, giving a milk-white globule, and colors the flame crimson.

Some visual examples are the bluish crystals in England, seen in gypsum and sulfur deposits in Italy, large crystals in the USA, pale-blue crystals in basalt cavities in Italy, and in pegmatites in Bohemia and Madagascar.

The specific gravity [?] for Celestine is 3.98, it's refractive index [?] is 1.62-1.63, and it's double refraction [?] is 0.01.

History

Celestine got its name from the Latin word for "celestial," after the beautiful pale color shown by some of its finest crystals. It is also known as celestite.

Industrial Usages

Celestine is the chief ore of strontium. Strontium and its salts are used in fireworks and flares to impart a strong crimson color. The crimson coloration of the flame is one of the tests used for identifying strontium salts.


It is also used in the nuclear industry, in the manufacture of rubber, paint and electrical batteries, in the refining of beet sugar and in the preparation of iridescent glass and porcelain. It is much sought-after by museums and collectors.


Ornamental-quality celestine is found in Bristol (England). Most faceted celestine comes from Madagascar (blue), or Canada (orange). Facetable crystals come from Tsumeb (Namibia).

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Terms

Double Refraction or dr is the ability of a mineral to separate a refracted ray of light into 2 rays. If held over an image or text it will display the object 2x its original size.

Mohs Scale of Mineral Hardness is the standard used to categorize a mineral's ability to resist scratching. It gets its name from Friedrich Mohs, the German geologist who first created the scale.

RI or Refractive Index defines light's ability to move through the mineral or in a general sense, any material.

SG or Specific Gravity is the ratio of the weight of any substance to that of pure water at temperature of 3.98°C(39.2°F) and standard atmospheric pressure. This is important to note when actively seeking these minerals in the wild. Minerals with a higher SG will settle below material with a lower sg over time.