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AZURESTONE. Geognostic Situation. Its geognostic situation is still imperfectly known. It a Ppears sometimes to occur in primitive limestone, along with iron pyrites, in Persia, Tartary and China; in veins that traverse granite, along with quartz, mica, and iron- Pyrites in the Altain mountains; and at the southern etul of the Lake Baikal in Siberia, in a vein, associated with garnets, mica, felspar, and iron-pvrites. Geographic Situation. It is found in Persia, Bucharia, China, Great Tartary, an d Siberia. Mr Pennant, in his Outlines of the Globe, informs us, that it is found in considerable quantities in the Island of Hainan in the Chinese sea, from whence it | 3 s ent to Canton, where it is employed in china paint ing. Uses. i Ho account of its beautiful blue colour, and the fine P°i‘sh it is capable of receiving, it is much prized by la- l»daries, and is cut as ring-stones, seal-stones, vases, snuff-boxes, and other ornamental articles of the same nature: it j s a ] so use( i j n mosaic and Florentine work. It is highly valued by painters, on account of the fine nltramarine blue colour obtained from it. The whole art in preparing this colour, consists in free- 5n g the azurestone from all impurities, and reducing it t° an extremely fine powder. This is done in the follow - ln g manner: The azurestone is first reduced to a coarse powder, and then exposed for an hour in a crucible to a P^ e tty strong heat. Vinegar is then poured on it, an( l t e whole is allowed to stand for some days: °t the end this time, the vinegar is poured oil", and the powder is Y 3 , sti11