China stone

China-clay rack is a kaolinized granite made up chiefly of quartz and kaolin, with sometimes tire presence of muscovite and tourmaline. The rock crumbles easily in the lingers. China stone is 11) a partially kaolinized granite, which contains quartz, kaolin, and sometimes mica and fluorite, is harder than china-clay rock and is used as a glaze in the production ol china or (2i a fine-grained, compact mudstone or limestone found in England and Wales... 

Bone China. Vitreous, translucent pottery made from a body of the following approximate composition (per cent) calcined bone, 45-50 china clay, 20-25, china stone, 25-30. The... 

Carolina Stone. A china stone (q.v.) used to some extent in the US pottery industry. 

China Stone. Partly decomposed granite, consisting of feldspathic minerals and quartz, it is used as a flux in pottery bodies. Examples in the UK are Cornish Stone and Manx Stone. The former is available in various grades, e.g. Hard Purple, Mild Purple, Hard White and Soft White the feldspars are least altered in the Hard Purple, alteration to secondary mica and kaolinite being progressively greater in the Mild Purple, Hard White, and Soft White the purple stones are so coloured by the small amount of fluorspar present. Manx Stone (from Foxdale, Isle of Man) is virtually free from fluorine. 

Cornish Stone. See china stone. Corridor Dryer. Term sometimes used for a CHAMBER DRYER (q.V.). 

Manx Stone. See china stone. Marbleized. A vitreous-enamel finish resembling marble it can be obtained by an offset process from natural marble. Marbling. A procedure sometimes used by the studio potter the marble effect is obtained by covering the piece of previously dried ware with coloured slips and then shaking the ware (while the slips are still wet) to make the colours run into one another. 

Mason s Ironstone China. A vitrified type of earthenware introduced by C. J. Mason, Stoke-on-Trent, England. According to his patent (Brit. Pat. 3724, 1813) the batch composition was 4 pts. china clay, 4 pts. china stone, 4 pts. flint, 3 pts. prepared ironstone, and a trace of cobalt oxide. It is now known that the body did not contain ironstone, the name merely being a highly successful method of indicating to the public that the ware was very strong. 

MEL. Maximum Exposure Limit Meldon Stone. A china stone (q.v.) of low quality from Cornwall, England. A quoted analysis is (per cent) Si02, 70 AI2O3,18 Fe203, 0.4 CaO, 0.6 Na20,4 K20,4.5 loss on ignition, 2.5. 

Peach Bloom. A glaze effect on pottery produced by the Chinese and characterized by its soft pink colour with patches of deeper red. It is achieved by the addition of copper oxide to a high-alkali glaze but requires very careful control of the kiln atmosphere the bloom results from incipient devitrification of the glaze surface. Peacock Blue. A ceramic colour made from a batch such as 33% Cobalt oxide, 7% standard black (q.v.), 45% China Stone, 15% Flint. 

Shell-stone. A china stone (q.v.) from Cornwall containing too much iron (as brown mica) for use as a flux in pottery glazes but of potential value in sewer-pipe glazes. 

Stone. A crystalline inclusion present as a fault in glass stones may result from incomplete reaction of particles of batch or from the pick-up of small fragments of the refractory lining of the pot or furnace in which the glass is melted. The most common constituents of stones are carnegieite, corundum, cristobalite, mullite, nephelite, tridymite and zirconia. See also china stone. 

Wagner JC, Pooley FD, Gibbs A et al (1986) Inhalation of china stone and china clay dusts relationship between the mineralogy of dust retained in the lungs and pathological changes. Thorax 41 190-196... 

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