Cryolite

This substance has hitherto been found only in Greenland, and was brought to Copenhagen, where Abildgaard analysed it, and found it to be a new mineral, not only from its constituent parts, but from its form and fracture. The latter is remarkable for being at right angles, and more or less tabular, and is as conspicuous as massy crystallized common Carbonate of Lime, to which it has much resemblance in colour and transparency, being greyish or whitish. It is softer than Fluate of Lime, and may be scratched by it; it is more brittle than either Carbonate or Fluate of Lime; it melts easily before the blow-pipe, even before it is heated red, or even by the flame of a candle, whence its name Cryolite, from κρυος and λίθος, as if it melted as easily as ice. Spec. Grav. 2.949.

Dr. Leftsom brought a fine and large specimen to shew to the Geological Society a few weeks since, which he possesses, and is perhaps the largest yet known. It is as yet reckoned very rare. Our specimen is fioin the collection of the British Museum.

The brown parts of the lower figure are Spathose Iron ore in brown rhomboidal crystals, which are imbedded in the Cryolite; it is accompanied also by Galaena and Sulphuret of Copper.