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224 FLUOR FAMILY. > is deprived of its phosphorescent property. The violet- blue variety from Nertschinskoi, named Chlorophanc, when placed on glowing coals, does not decrepitate, hut soon throws out a beautiful verdigris-green and apple- green light, which gradually disappears as the mineral cools, but may be again excited, if it is heated; and this may be repeated a dozen of times, provided the heat is not too high. When the chlorophane is exposed to a red- heat, its phosphorescent property is entirely destroyed. Pallas mentions a pale violet-blue variety spotted with green, from Catharinenburg, which is so highly phos phorescent, that when held in the hand for some time, it throws out a pale whitish light; when placed in boiling water, a green light; and exposed to a higher tempera ture, a bright blue light. When sulphuric acid is added to heated fluor-spar, in the state of powder, a white pe netrating vapour (the fluoric acid) is evolved, which has the property of corroding glass. Constituent Parts. From Northumberland. From Gertdorf. Lime, - . 67.34 67.75 Fluoric Acid, - 32.66 32.25 100.00 100.00 Thomson, in Wern. Klaproth, Beit. Mem. vol. i. 11. b. iv. s. 365. Geognostic Situation. It occurs principally in veins, that traverse, primitive, transition, and sometimes floetz rocks; also in beds, asso ciated with other minerals; in kidneys in floetz lime stone ; and in drusy cavities in trap-rocks. It sometimes forms the petrifying mineral in fossil organic remains: thij»j