Fluorite

Physical properties
Fluorite is rarely found at Franklin in cubic crystals but commonly in cleavage masses or in compact granular form. Its color ranges from rose-red to pale flesh-color, purple, gray, and white. Its specific gravity is 3.188.

Composition
In the belief that the pale-red fluorite found enclosing franklinite in the Parker shaft is manganiferous, some of it, free from inclusions, was selected and was sent for analysis to the laboratory of the United States Geological Survey.

**Analysis of fluorite**
(George Steiger (195), analyst)
	Percent	Molecular ratio
Ca	51.21	1.28*
Mg	0.24	0.01*
Fe	0.27	0.005*	1.303
Mn	0.09	0.002*
Al	0.18	0.006*
F	45.85		2.412
	97.84

[*Figures reflected in the value 1.303 shown at right]

Steiger states that the deficiency in the analysis is undoubtedly to be assigned to fluorine, also that the Al, Fe, Mg, and Mn are computed as fluorides, although they may be present as oxygen salts.

The amount of manganese reported is not sufficient to be remarkable. If the total deficiency, 2.16 percent, is computed as fluorine there is still slightly less of that element than is needed to form RF₂ with all the bases, but almost exactly enough to satisfy calcium. This suggests, but of course does not prove, that the bases other than calcium are present as impurities or as unknown oxygen salts.

Occurrence
Fluorite is fairly common in the ore body at Franklin as the matrix of ore minerals and other, rarer species. Thus a red variety, as described above, is found at the Parker shaft. In the Fiss collection; microscopic pure-white, simple dodecahedrons implanted on axinite were seen. They are apparently fluorite and probably came from the Parker shaft. At the Trotter mine, where were found the nickel minerals, fluorite was abundant at one point, in dark-purple and pink cleavage masses. Veinlike masses of red and purple fluorite from the Buckwheat mine were also seen.

In the white limestone of all the quarries about Franklin, gray to purple Fluorite is locally abundant in compact granular form, and it is also seen in the pegmatite dikes cutting the limestone. The occurrence of fluorite in limestone was first described by Bruce (2), and his mention of it is of historic interest as the first recorded observation of this mineral in America.

In the blue (Kittatinny) limestone near Franklin there are a few cavities in which have been found small cubes and octahedrons of purple fluorite, associated with crystals of quartz and calcite.


	Website © by Herb Yeates 1997-2001.
	This page created: January 12, 2001 6:16 PM