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According to George Hurst in, "A manual of Painters Colours, Oils and Varnishes" published by Charles Griffin and Co in 1913. "Barium Carbonate is obtained by precipitating barium salts with sodium carbonate, it is produced in large quantities as a bye product but is not vey frequently used as a pigment" (white). If this is suggesting that it is availible in large quantities from the chemical industry it sound like it would be cheaper to use that source rather than mined witherite. The same book suggests that barytes is not used as a pigment but as a filler in cheap paints. Both are listed under mineral whites, other mineral whites mentioned are strontian white, magnesium carbonate, calcium carbonate, aluminium oxide, aluminium silicate and powdered asbestos which is also widely used in cheap paint. Worth thinking about if you live in a house from the early 1900s and are contemplating decorating! Martin Roe _________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com