Barite

Barite

The name Barites (also known as barite, heavy spar, bar, tiff and baryta) is derived from the Greek word “baros” meaning “heavy”, referring to its most striking feature.

Barites is a naturally occurring barium sulphate with a chemical formula BaSO4 (BaO 65.7% and SO3 34.3%). It is the most widespread anhydrous sulphate after anhydrite. In nature, barites is generally of hydrothermal origin and sometimes it also formed by leaching of barium compounds from rocks. As an accessory mineral it is found in the sulphides of manganese, iron and other metals.

Barites is also widespread in sedimentary rocks as concretions. Barites occurs both as veins and as bedded deposits, and mining is by both underground and opencast methods. The world’s largest bedded barites deposit occurs in Mangampet, Cuddapah district, Andhra Pradesh, India. Of the total world production of 7.4 million tons in 2001, about 54% was accounted for by China alone. The other leading producers were India, Morocco, USA, Iran and Mexico.
Barites is a crystalline (orthorhombic) mineral occurring in globular, massive, rosette, fibrous, and crystal forms. It has perfect cleavage. But the most important properties from the point of view of industrial application are as follows.
1. Specific gravity: The most striking characteristic of barites is its high specific gravity. The specific gravity of pure barites is 4.5 (c.f., magnetite 5.18) and this can vary downward, depending on the impurities present. The mineral even feels heavy in hand.
2. Sound-deadening ability: The high density enables barites to slow down propagation of sound waves and it is thus an efficient sound-deadener.
3. Radiation adsorption: Barites can adsorb different kinds of radiation—X-rays, neutrons, gamma-rays.
4. Colour and other optical properties: Pure barites is bright snow-white opaque to transparent but impurities cause a wide variation in colour. Brightness of pure barites as measured in terms of the reflectance of blue wave of light (wave length 457 micron) is 98.5 (c.f., for TiO2—a standard reference, the value is 97-98). Whiteness of such barites as measured in terms of ‘L’ value is 99 (c.f., for TiO2—a standard reference, the value is 98-100). Its lustre is vitreous to resinous. Refractive index of barites is about 1.64.
5. Hardness and fracture: Its hardness varies from 3 to 3.5 on Mohs scale and it is brittle, easily breaking with an uneven fracture. These properties make it nonabrasive in character.
6. Chemical characteristics: Chemically, barites is BaSO4, but, in nature, it usually contains impurities like SiO2, Al2O3, Fe2O3, clay, fluorite and carbonates. Barites contains little or no soluble salts and it is insoluble in water and acid. It is chemically inert with pH value 6-8 (pH value of 7 means neutrality).
7. Oil absorption: Its oil absorption is low.
8. Thermal property: Barites dissociates into barium sulphide (BaS) and oxygen at
13000C.

The important uses of barites are:
1. Oil-well drilling
2. Paint
3. Chemicals
4. Barium metal recovery
5. Glass
6. Paper
7. Rubber
8. Coal washing
9. Explosive
10. Concrete aggregate
11. Nuclear reactors and other radiation equipments
12. Radiology
13. Children’s toys
14. Adhesives

*Adapted from the book USES OF INDUSTRIAL MINERALS, ROCKS AND FRESHWATER - KAULIR KISOR CHATTERJEE