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/ Chrysopras. r 193 \ Geognostic Situation. ' .ri It is found along with quartz, opal, chalcedony, albeft, lithomarge, &c. in Terpentine. Geographic Situation. It has been hitherto found only at Kofemutz in lower Silefia. Vfe. It is principally ufed for ring ftones, but is rather difficult to cut and polilh. The apple green variety is the moll highly valued, and ring ftones of that co lour are ufually valued at 12I. Obfcreations. r. It pafles into hornftone and chalcedony, and into a fofiil which is intermediate between chrifopvas and opal. 2. It lofes much of its colour, when long kept in a warm and dry place, or when much expofed to the nifluence of the air ; on this account mineral dealers are careful to preferve their fpecimens in moift places. C c 3- ^ )