Arenaceous Fluate of Lime

Fluor is not only found crystallized in company with Quartz, Sulphate of Barytes, Galaena, &c., in aggregate groups, but detached in very small cubic Crystals scattered in the Lime rock—see the upper figure, where the Fluor is seen in dark cubes scattered among brown Limestone. Fluor is also found stratified in cubes smaller and smaller until the eye cannot discern them, being in sand-like grains, and finally pulverulent and undistinguishable from their fineness, even passing dendritically among the Carbonate of Lime or Sulphate of Barytes. The noble-spirited Dr. Jackson, who will always sacrifice the best of his collection for public use, was so good as to give me a beautiful large specimen of this kind with Calamine and Galaena, the latter of which is often found in small detached Crystals in the same rock with the Fluor.

The lower figure is granular and pulverulent Fluor, repeatedly stratified with Sulphate of Barytes, which is not very common in an earthy form. Fluor is often of a fine colour when the Crystals are transparent, their transparency often giving great brilliancy to their colour. The middle specimen is a good example of a tolerably fine purple in the granular or dusty form, which form is seldom advantageous to colour.

The specimens are chiefly from the neighbourhood of Castleton in Derbyshire: such are indeed found in other parts, but not frequently.