FLUOR SPAR

This is a common mineral product, found in great beauty in Derby shire; hence known in this country under the name of the Derby shire spar. It is generally crystallized in cubes, but its primitive form is an octahedron. It is of various colours, and often beautifully banded; especially when in nodules, which are much prized for the manufacture of vases, and occasionally used for beads, brooch stones, and other ornamental purposes. It is probably a compound of fluorine and calcium, hence a fluoride qf calcium. The term fltior is derived from the fusibility of this substance; on which account it is sometimes used as a flux to promote the fusion of certain refractory minerals. It is manufactured at Matlock and Derby into a great variety of articles. [s. 471]