Dictionary:

celestite

  (sĕl'ĭ-stīt', sə-lĕs'tīt')

A white, red-brown, orange, or light blue principal strontium ore, essentially strontium sulfate, SrSO₄, found in sedimentary rock. Also called celestine.

[CELESTINE + –ITE¹.]

A mineral with the chemical composition SrSO4. Celestite occurs commonly in colorless to sky-blue, orthorhombic, tabular crystals. Fracture is uneven and luster is vitreous. Hardness is 3–3.5 on Mohs scale and specific gravity is 3.97. It fuses readily to a white pearl. The strontium present in celestite imparts a characteristic crimson color to the flame.

Celestite occurs in association with gypsum, anhydrite, salt beds, limestone, and dolomite. Large crystals are found in vugs or cavities of limestone. It is deposited directly from sea water, by groundwater, or from hydrothermal solutions. Celestite is the major source of strontium: Although celestite deposits occur in Arizona and California, domestic production of celestite has been small and sporadic. Much of the strontium demand is satisfied by imported ores from England and Mexico. See also Strontium.

Environment

Sedimentary rocks; rather rarely a gangue mineral of ore veins.

Usually in crystals, commonly tabular, resembling barite; also granular and in fibrous veins.

Pale blue to deep and splotchy blue, white, colorless, red-brown, orange. Luster glassy; hardness 3-3Ɖ; specific gravity 3.9-4.0; fracture uneven; cleavage like barite, perfect basal and prismatic and poor pinacoidal. Brittle; transparent to translucent; sometimes fluorescent.

Strontium sulfate (56.4% SrO, 43.6% SO ₃ ).

Cracks, fuses with difficulty on charcoal. After firing, with whitening of the surface, fluoresces and phosphoresces bright green. Gives sulfur test with silver.

Light blue color, which often tints only part of the otherwise white crystal, is the best diagnostic point. The flame test can only be confused with that from anhydrite (but calcium much less red than strontium). Similar minerals of other groups can be distinguished by the softness and acid insolubility of the celestite, and the greenish fluorescence after heating.

Only rarely an accessory mineral of ore veins that were formed from warm solutions (Cripple Creek, Colorado). Usually found in sedimentary rocks; the best occurrences are in cavities in sandstone or limestone, associated with fluorite, calcite, gypsum, dolomite, galena, and sphalerite. Its color in these occurrences very often is the characteristic blue.

Fine, white, elongated, square crystals, an inch (2-3 cm) or so in length, were abundant in the Sicilian sulfur mines, associated with sulfur. Small blue crystals of similar habit were found on a white calcite at Herrengrund (now Spania Dolina, Czechoslovakia). Large flat white blades are found in England at Yate, Gloucestershire.

There are many occurrences in the U.S. Tremendous crystals were found on Kelleys I., Lake Erie, in a large limestone quarry. Some of these crystals were 6-8 in. (15-20 cm) across. A more recent outstanding locality from the standpoint of abundance is Clay Center, Ohio (another limestone quarry), in which pockets are filled with fine blue-to-white bladed celestite, associated with a brown fluorite and yellowish calcite. Some of the white crystals are very thin and fragile; others are thicker, blue, and resemble barite. Other quarries in that area are known for their celestite. Good crystals have also been found at Chittenango Falls, New York.

Geodes with large blue crystals much like those from Kelleys I. are found at Lampasas, Texas. Colorless transparent crystals occur with the colemanite in geodes of the Death Valley area. Orange cloudy crystals are found near Hamilton, Ontario, and near Colorado Springs, Colorado, though in neither locality are they free-standing. Fine blue crystals are found near Manitou Springs, Colorado, and blue radiating columnar crystal intergrowths (a rare hydrothermal occurrence) were found in the gold mines at Cripple Creek, Colorado. A blue fibrous vein material from Bellwood, Blair Co., Pennsylvania, described in 1791, was the original celestite, the first discovery of this mineral, which is named for its color. Brilliant geodes lined with gemmy blue crystals are found near Sakoony, Bombetoka Bay, Madagascar, and are now available in great abundance.

The blue of celestite has been attributed to the presence of minute amounts of gold, but irradiation also turns some crystals a persistent blue.

The noun has one meaning:

Meaning #1: a mineral consisting of strontium sulphate