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Jasper, 241 Geognojiic Situation. " It is generally found in veins that occur in primi tive rocks, and is a iconftituent part of thofe agates a t are found in amygdaloid. It is frequently tra veled by quartz veins, and is fometimes mixed with Pyrites, lithomarge, femiopal, brown fpar and native and vitreous filver ore. It has been fuppofed to form e bafis of certain kinds of porphyry ; but this is the cafe ; the bafis of thefe porphyries, as Werner r obferved, is either hornftone, indurated clay, or C ° m pact felfpar. Geographic Situation. j"|t is found in Saxony, Bohemia, France, Spain, aiu/* 1IUngary ’ F-tifiia, Sweden, Shetland iflands*, the tranfition rocks near Edinburgh. •> Mineralogy of the Scottifh Ifles.
