- Barium carbonate
Name = Barium carbonate
OtherNames = witherite
Section1 = Chembox Identifiers
CASNo = 513-77-9
Section2 = Chembox Properties
Formula = BaCO3
MolarMass = 197.336 g/mol
Appearance = white crystals
Density = 4.2865 g/cm3, solid
Solubility = .0001 mol/l (25 °C)
MeltingPt = 811 °C
BoilingPt = 1555 °C
Witherite crystallizes in the orthorhombic system. The
crystals are invariably twinned together in groups of three, giving rise to pseudo-hexagonal forms somewhat resembling bipyramidal crystals of quartz, the faces are usually rough and striated horizontally.
The mineral is named after
William Withering, who in 1784 recognized it to be chemically distinct from barytes. It occurs in veins of lead oreat Hexhamin Northumberland, Alston in Cumbria, Anglezarke, near Chorleyin Lancashireand a few other localities. Witherite is readily altered to barium sulfateby the action of water containing calciumsulfate in solution and crystals are therefore frequently encrusted with barytes. It is the chief source of barium salts and is mined in considerable amounts in Northumberland. It is used for the preparation of rat poison, in the manufacture of glassand porcelain, and formerly for refining sugar. It is also used for controlling the chromateto sulfateratio in chromium electroplatingbaths. [cite web
last = Whitelaw
first = G.P.
title = Standard Chrome Bath Control
publisher = finishing.com
url = http://www.finishing.com/Library/Whitelawchrome.html
accessdate = 2006-11-29 ]
Barium carbonate reacts with many acids to soluble barium salts, for example
However the reaction with
sulfuric acidis poor, because barium sulfateis highly insoluble.
Barium carbonate is widely used in the ceramics industry as an ingredient in glazes. It acts as a flux, a matting and crystallizing agent and combines with certain coloring oxides to produce unique colors not easily attainable by other means. Its use is somewhat controversial since it can leach from glazes into food and drink. To provide a safe means of use, BaO is often used in
In the brick, tile, earthenware and pottery industries barium carbonate is added to clays to precipitate soluble salts (calcium and magnesium sulfates) that cause
[http://ceramic-materials.com/cermat/material/86.html Barium Carbonate at CeramicMaterials.Info]
[http://ceramic-materials.com/cermat/education/138.html The use of barium in clay bodies]
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