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The potter's clay derives its origin from several felspathic rocks, which under various influences have been decomposed, and the finest portion washed away, to be collected in natural depressions of the soil, where it has formed beds of various thickness.

He wanted to produce a porcelain without fritt and with a felspathic glaze, and, in succeeding in his attempt, this energetic man is entitled to a great deal of credit, when we consider that, although the processes discovered by Bottger, in 1710, at Meyssen, for making hard porcelain, were also put in practice at Vienna, St. Petersburg, and Berlin, they were kept very secret, and it is most probable that he had no information whatever from those quarters.

Clay.—A yellowish-white, non-vitreous clay, product of the decomposition of granitic or felspathic rocks.

The Wolf lighthouse is planted on a dangerous rock of felspathic porphyry some eight miles S.W. from the shore.

But not to slumber long; for, glad to have made a new mineral combination, thou didst thrust forth at the northern point of thy work the great trachytic mass of the Puy de D�me: there it stands with its solid hump of felspathic crystals, a vast watch-tower of creation—white and purple within, glassy-green without.