Cornish stone

The clays vary much in quality, some being mucli more aluminous than others, and, although not so whitz,yet possessing most valuable qualities, and making very sound wares. Beneath the argillaceous strata lie the Cornish stone, which te harder in texture, and can. be quarried in masses ready for shipment.,... 

Granite or Cornish-stone clay, previously dried at 212°, was found to consist of—... 

Tho crude materials used in England in the manufacture of fine earthenware, are Cornish stone and China clay, a kind of kaolin brought from Cornwall, two varieties of plastic clay, both of which burn white, and chalk-flints. That class called ironstone china is made from ft mixture of plastic clay, kaolin, Comish stone in excess, and silica, Hie formula of which is subjoined —... 

The Cornish stone is brought from Cornwall in masses for the purpose of being ground and prepared, but without the process of calcination, and is used in... 

The total quantity of potters material—such as Cornish stone, flint, kaolin, china clay, pool day, felspar, et cetera—used in the various departments of manufacture in the Staffordshire potteries, during the year 1859, is estimated at not less than two hundred and twenty thousand tons the. manufactured ware sent out of the district during the same period, reaching over one hundred and ten thousand tons, which, taken at an average value of twenty-five pounds per ton. will give the enormous sum of two millions five hundred thousand pounds sterling. 

Frit composed of Cornish stone. 20 T Calcined in Frit composed o soda. If f gloss oven,. 

China Clay, The product obtd by leaching weathered deposits of granitic rocks, so that quartz mica portions are removed (Ref 1). For example, when Feldspar weathers, the first product is Cornish stone this next becomes china clay rock from which the china clay is obtd. The purest china clay is known as kaolin and consists mainly of hydrated aluminum silicate(Ref 2)... 

Table 19 Chemical Analyses of Some Varieties of Cornish Stone...

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.). 

Other types of soft-paste porcelains developed (Figure 2.10), particularly in England where the most famous were porcelains containing bone ashes, kaolin and Cornish stone (feldspathic rock used as flux). 

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