Fluor

This beautiful substance is sometimes cut and polished for various ornamental purposes, as before mentioned, tab. 411, &c. It is also occasionally cut into little slabs shoeing the beautiful and very instructive varieties. Thus, while we see the radiating or diverging structure, we sec how much it does or does not interrupt the crystallization; we see also its tendency to crystallize under every circumstance: and these specimens mark it more or less distinctly by the colour, at every period or effort in extending the radii; marking the right angles of the cubes, which are sometimes extremely sharp and conspicuous, and are so softly blended at others as only to be distinguishable by faint dots. The whole being so compact is the more remarkable, because the state of fluidity in which it formed would from this appear to have been equal; which makes it difficult to theorize upon.

The square slab below is a transverse section of the radii, and exhibits an admirably reticulated structure, from the opacity of the division of the radii in different proportions.