Page:Cornwall; Cambridge county geographies.djvu/100

 84 CORNWALL the mine having fallen into discredit, or the water having broken in. But if tin mining be practically dead in Cornwall, another industry has risen with leaps and bounds. It is that of the china-clay and china-stone, employed in the manufacture of porcelain, in the sizing of paper and of cotton materials, in the manufacture of alum, etc. The China Clay Quarries, Porthpean glazed paper so largely employed in our illustrated papers is made up largely with china-clay. Some years ago the Italian government employed this paper for its official documents, but found that after a few years under the influence of damp weather the records had dissolved into a lump of clay. China-clay consists of decomposed felspar, quartz and