Baryte

Baryte (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/cm^3[1]
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	[2][3][4][5]

Baryte or barite (BaSO₄) is a mineral consisting of barium sulfate.^[2] 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.^[1]

Names and history

The unit cell of baryte

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.^[6]

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.

Name

The name baryte is derived from the Greek word βαρύς (heavy). The American spelling is barite.^[2][7] The International Mineralogical Association adopted "barite" as the official spelling when it formed in 1959, but recommended adopting the older "baryte" spelling in 1978,^[8] notably ignored by the Mineralogical Society of America.

Other names have been used for baryte, including barytine,^[8] barytite,^[8] schwerspath,^[8] Heavy Spar,^[2] tiff,^[3] and blanc fixe.

Mineral associations and locations

Baryte with galena and hematite from Poland

Large baryte crystals from Nevada, US

Abandoned baryte mine shaft near Aberfeldy, Perthshire, Scotland

Baryte occurs in a large number of depositional environments, and is deposited through a large number of processes including biogenic, hydrothermal, and evaporation, among others.^[1] Baryte commonly occurs in lead-zinc veins in limestones, in hot spring deposits, and with hematite ore. It is often associated with the minerals anglesite and celestine. It has also been identified in meteorites.^[9]

Baryte has been found at locations in Brazil, Nigeria, Canada, Chile, China, India, Pakistan, Germany, Greece, Guatemala, Iran, Ireland (where it was mined on Benbulben^[10]), Liberia, Mexico, Morocco, Peru, Romania (Baia Sprie), Turkey, South Africa (Barberton Mountain Land),^[11] Thailand, UK (Cornwall, Cumbria, Derbyshire, Durham,^[12] Perthshire, Argyllshire and Surrey^[2]) and in the US from Cheshire, Connecticut, De Kalb, New York and Fort Wallace, New Mexico. It is mined in Arkansas, Connecticut, Virginia, North Carolina, Georgia, Tennessee, Kentucky, Nevada and Missouri.^[2]

World baryte production for 2014 was 9.7 million tonnes. The major baryte producers (in thousand tonnes, data for 2014) are as follows: China (4,100), India (1,200), Morocco (1,200), United States (1,100), Mexico (420), Iran (350), Turkey (340) and Kazakhstan (200).^[13]

The main users of baryte in 2014 were (in million tonnes) US (3.39), China (1.45), Gulf States (0.78), the European Union and Norway (0.61), South America (0.37), India (0.35), Canada (0.29) and Africa (0.28).^[13]

Uses

77% of baryte worldwide is used as a weighting agent for drilling fluids in oil and gas exploration to suppress high formation pressures and prevent blowouts. As a well is drilled, the bit passes through various formations, each with different characteristics. The deeper the hole, the more baryte is needed as a percentage of the total mud mix. An additional benefit of baryte is that it is non-magnetic and thus does not interfere with magnetic measurements taken in the borehole, either during logging-while-drilling or in separate drill hole logging. Baryte used for drilling petroleum wells can be black, blue, brown or gray depending on the ore body. The baryte is finely ground so that at least 97% of the material, by weight, can pass through a 200-mesh (75-μm) screen, and no more than 30%, by weight, can be less than 6 μm diameter. The ground baryte also must be dense enough so that its specific gravity is 4.2 or greater, soft enough to not damage the bearings of a tricone drill bit, chemically inert, and containing no more than 250 milligrams per kilogram of soluble alkaline salts.^[7] In August 2010 API (American Petroleum Institute) published specifications to modify the 4.2 drilling grade standards for baryte to include 4.1 SG materials.

Other uses are in added-value applications which include filler in paint and plastics, sound reduction in engine compartments, coat of automobile finishes for smoothness and corrosion resistance, friction products for automobiles and trucks, radiation-shielding cement, glass ceramics and medical applications (for example, a barium meal before a contrast CAT scan). Baryte is supplied in a variety of forms and the price depends on the amount of processing; filler applications commanding higher prices following intense physical processing by grinding and micronising, and there are further premiums for whiteness and brightness and color.^[7] It is also used to produce other barium chemicals, notably barium carbonate which is used for the manufacture of LED glass for television and computer screens ( historically in cathode ray tubes); and for dielectrics.

Historically baryte was used for the production of barium hydroxide for sugar refining, and as a white pigment for textiles, paper, and paint.^[2]

Although baryte contains a "heavy" metal (barium), it is not a toxic chemical because of its extreme insolubility.

It is also sometimes used as gemstone.^[14]

Oxygen and sulfur isotope records

Baryte with cerussite from Morocco

In the deep ocean, away from continental sources of sediment, pelagic baryte precipitates and forms a significant amount of the sediments. Since baryte has oxygen, systematics in the δ¹⁸O of these sediments have been used to help constrain paleotemperatures for oceanic crust.

The variations in sulfur isotopes (³⁴S/³²S) are being examined in evaporite minerals containing sulfur (ex, baryte) and carbonate associated sulfates (CAS) to determine past seawater sulfur concentrations which can help identify specific depositonal periods such as anoxic or oxic conditions. The use of sulfur isotope reconstruction is often paired with oxygen when a molecule contains both elements.^[15]

See also

• Rose rock

References

1. Hanor, J. (2000). "Barite-celestine geochemistry and environments of formation". Reviews in Mineralogy. Washington, DC: Mineralogical Society of America. 40: 193–275. ISBN 0-939950-52-9.
2. Dana, James Dwight; Ford, William Ebenezer (1915). Dana's Manual of Mineralogy for the Student of Elementary Mineralogy, the Mining Engineer, the Geologist, the Prospector, the Collector, Etc. (13 ed.). John Wiley & Sons, Inc. pp. 299–300.
3. Barite at Mindat
4. Webmineral data for barite
5. Baryte, Handbook of Mineralogy
6. History of the Bologna stone
7. M. Michael Miller Barite, 2009 Minerals Yearbook
8. "International Mineralogical Association: Commission on New Minerals and Mineral Names". Mineralogical Magazine. 38 (293): 102–5. March 1971. doi:10.1180/minmag.1971.038.293.14.
9. Rubin, Alan E. (March 1997). "Mineralogy of meteorite groups". Meteoritics & Planetary Science. 32 (2): 231–247. Bibcode:1997M&PS...32..231R. doi:10.1111/j.1945-5100.1997.tb01262.x.
10. Ben Bulben. Mhti.com. Retrieved on 2011-05-05.
11. Duchač, K. C; Hanor, J. S. (September 1987). "Origin and timing of the metasomatic silicification of an early Archaean komatiite sequence, Barberton Mountain Land, South Africa". Precambrian Research. 37 (2): 125–146. doi:10.1016/0301-9268(87)90075-1. ISSN 0301-9268.
12. Muirshiel Mine
13. The Barytes Association, Barytes Statistics
14. Gemstones: Properties, Identification and Use By Arthur Thomas p.138
15. Kastner, Miriam (30 March 1999). "Oceanic minerals: Their origin, nature of their environment, and significance". Proc. Natl. Acad. Sci. U.S.A. 96 (7): 3380–7. Bibcode:1999PNAS...96.3380K. doi:10.1073/pnas.96.7.3380. PMC 34278. PMID 10097047.

 This article incorporates public domain material from the United States Geological Survey document: "Barite" (PDF).