Barites
| Barytes (barite) | |
|---|---|
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 1971, notably ignored by the Mineralogical Society of America.
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