GUR.HOFITE. 113 It occurs massive. It is dull. The fracture is Hat conchoidal, passing into even. The fragments are sharp-edged. It is slightly translucent on the edges. It is hard, bordering on semi-hard. It is brittle. It is rather difficultly frangible. Specific gravity, 2.7000, Karslen. Chemical Characters. When pounded, and thrown into diluted and heated nitrous acid, it is completely dissolved with effervescence. Constituent Parts. Carbonate of Lime, - 70.50 Carbonate of Magnesia, - 29.50 100 Klaproth, Gesellch. N. Fr. b. i. s. 258. Gcognostic and Geographic Situations. It forms a vein in serpentine, in the rocks between Gurhof and Aggsbach, in Lower Austria. Observations. 1. The name Gurhofite, is from the place near which it is found. 2. It was at one time considered to be a variety of semi-opal; but its greater weight distinguishes it lrom that mineral. Vol. II. H XX. LIME-