Fluorite deposition

Like other fluorite deposits, the Albigeois ores are notable for their high grade. In veins of the Le Bure deposit, for example, fluorite comprises 90% of the ore volume (Deloule, 1982). Accessory minerals include quartz (SiCh), siderite (FeCCL), chalcopyrite (CuFeSg), and small amounts of arsenopyrite (AsFeS). The deposits occur in a tectonically complex terrain dominated by metamorphic, plutonic, and volcanic rocks and sediments. 

As shown in Figure 22.1, quenching is effective at producing fluorite. The process, however, is somewhat less efficient than simple cooling because of the counter-effect of dilution, which limits precipitation and eventually begins to cause the fluorite that formed early in the reaction path to redissolve. Each mechanism of fluorite deposition is quite efficient, nonetheless, producing - over a temperature drop of just 50 °C - about a cm3 or more mineral per kg of water in the ore fluid. 

Triboluminescence, from the Greek word tribein (to rub) is a term used to describe the visible (and UV) emissions of materials when they are stressed to failure. This phenomenon is very common among minerals (see Table I), and is well known to spelunkers who enjoy smashing fluorite deposits to see the light. Earthquake lights (1) (2) are probably triboluminescence on a grand scale. 

Fluorine occurs in nature in the form of the minerals fluorite, CaF2, cryolite, Na3AlF6, and fluoroapatite, Ca5(P04)3F, and one commercial source of natural cryolite is Greenland. Both of the other minerals are widespread in nature, although the major use of fluoroapatite is in the production of fertilizers, not as a primary source of fluorine. Extensive fluorite deposits are found in Southeastern Illinois and Northwestern Kentucky. From the standpoint of fluorine utilization, both cryolite and fluorite are extremely important minerals. Cryolite is used as the electrolyte in the electrochemical production of aluminum from bauxite, and fluorite is used as a flux in making steel. Today, most of the cryolite used is synthetic rather than the naturally occurring mineral. 

Richardson C. K. and Holland H. D. (1979) Fluorite deposition in hydrothermal systems. Geochim. Cosmochim. Acta 43, 1327-1336. 

The location of Gardinier s plant in relation to Tampa Bay is indicated in Figure 1. Two canals discharge processing wastes into the Bay. A deltaic deposit of fluorite that may be the only such deposit of sedimentary fluorite known in the world is located at the mouth of both canals. In cross-section, the fluorite deposit is about 3 in. thick at the... 

The present study indicates the use of a fiuoride specific ion electrode as a means of measuring fluoride as a specific pollutant, but more to the point, the study indicates the possibility of environmental restoration when specific emissions are curtailed. If the abatement program is continued, apart from occasional accidental lapses, a significant result of the unique deltaic sedimentary fluorite deposit may be anticipated— fishing should be better there than in many places of Tampa Bay where absence of a firm bottom contributes to turbidity problems during storms and prevents benthic plants from using a useful niche. 

Barton, P.B., Jr., 1967. Possible role of organic matter in the precipitation of the Mississippi Valley ores. In J.S. Brown (Editor), Genesis of Statiform Lead-Zinc-Barite-Fluorite Deposits (Mississippi Valley Type Deposits). Econ. Geol., Monograph 3, pp. 363-369. 

Isotopic zoning of lead and sulfur in southeast Missouri. In Genesis of stratiform lead-zinc-fluorite deposits (Mississippi Valley type deposits). A symposium, New York, 1966. Econ. Geol., Mon. 3, 410—425 (1967). 

Polyakova, O. P., 1965. Nacrite from Eastern Transbaikal fluorite deposits. Izv. Akad. Nauk SSSR, Ser. Geol. 30 120. 

---