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Barite

Baryte (barite)
6158M-barite2.jpg
Baryte crystals from Cerro Huarihuyn, Miraflores, Huamalíes, Huánuco, Peru
(size 56 x 53 mm, 74 g)
General
Category Sulfate mineral, barite group
Formula
(repeating unit)
BaSO4
Strunz classification 7.AD.35
Dana classification 28.03.01.01
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Pnma
Unit cell a = 8.884(2) Å,
b = 5.457(3) Å,
c = 7.157(2) Å; Z = 4
Identification
Color Colorless, white, light shades of blue, yellow, grey, brown
Crystal habit Tabular parallel to base, fibrous, nodular to massive
Cleavage Perfect cleavage parallel to base and prism faces: {001} Perfect, {210} Perfect, {010} Imperfect
Fracture Irregular/uneven
Tenacity Brittle
Mohs scale hardness 3-3.5
Luster Vitreous, Pearly
Streak White
Diaphaneity transparent to opaque
Specific gravity 4.3–5
Density 4.48 g/cm3
Optical properties biaxial positive
Refractive index nα = 1.634–1.637
nβ = 1.636–1.638
nγ = 1.646–1.648
Birefringence 0.012
Fusibility 4, yellowish green barium flame
Diagnostic features white color, high specific gravity, characteristic cleavage and crystals
Solubility low
References

Baryte or barite (BaSO4) is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte is generally white or colorless, and is the main source of barium. Baryte and celestine form a solid solution (Ba,Sr)SO4.

The radiating form, sometimes referred to as Bologna Stone, attained some notoriety among alchemists for the phosphorescent specimens found in the 17th century near Bologna by Vincenzo Casciarolo.

The American Petroleum Institute specification API 13/ISO 13500, which governs baryte for drilling purposes, does not refer to any specific mineral, but rather a material that meets that specification. In practice, however, this is usually the mineral baryte.

The term "primary barytes" refers to the first marketable product, which includes crude baryte (run of mine) and the products of simple beneficiation methods, such as washing, jigging, heavy media separation, tabling, flotation. Most crude baryte requires some upgrading to minimum purity or density. Baryte that is used as an aggregate in a "heavy" cement is crushed and screened to a uniform size. Most baryte is ground to a small, uniform size before it is used as a filler or extender, an addition to industrial products, in the production of barium chemicals or a weighting agent in petroleum well drilling mud.

The name baryte is derived from the Greek word βαρύς (heavy). The American spelling is barite. The International Mineralogical Association adopted "barite" as the official spelling when it formed in 1959, but recommended adopting the older "baryte" spelling in 1978, notably ignored by the Mineralogical Society of America.


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