Triphane, Spodumene

This mineral, described by Dandrada, was found at Uton in Sweden, and also in Norway, disposed in Granite (Quartz with a little Feldspar and Mica), in various directions, in oblique four-sided more or less battery prisms, composed of plates, and which are generally narrowest on the most readily divisible sides. The surface of the plates is of a light green colour, but the prism terminating irregularly in the matrix, no apex, or even external surface, is to be discovered, and the cross-fracture shows dull small roughish fragments, and appear of a darker green colour. See the middle of the specimen. The middle geometrical figure shows the twofold direction of the lamina, and the diagonal fracture included in a square, and the manner in which the narrow sides are lost in the matrix, which in this specimen is mostly Quartz with a tinge approaching to purplish. The right-hand geometrical figure shows what Haüy considers as nearly the form of the nucleus, the angles of which are about 80°. and 100°. with the irregular oblique fractures on the sides. The other uncoloured one shows the nucleus distinctly, with the approximation at the diagonals of the two right-angled planes, to form the oblong parallelogram.

It is so hard as to scintillate with steel, scratch glass, &c. Heated in a crucible, it splits into numerous plates, some yellow, some dark grey; all lose their lustre in a few days, and are of the latter appearance. Before the blow-pipe it melts into a greyish globule. Spec. Grav. 3.1923 to 3.218.