Fluorite forms as a late-crystallizing mineral in felsic igneous rocks typically through hydrothermal activity.[15] It is particularly common in granitic pegmatites. It may occur as a vein deposit formed through hydrothermal activity particularly in limestones. In such vein deposits it can be associated with galena, sphalerite, barite, quartz, and calcite. Fluorite can also be found as a constituent of sedimentary rocks either as grains or as the cementing material in sandstone.[15]
It is a common mineral mainly distributed in South Africa, China, Mexico, Mongolia, the United Kingdom, the United States, Canada, Tanzania, Rwanda and Argentina.
The world reserves of fluorite are estimated at 230 million tonnes (Mt) with the largest deposits being in South Africa (about 41 Mt), Mexico (32 Mt) and China (24 Mt). China is leading the world production with about 3 Mt annually (in 2010), followed by Mexico (1.0 Mt), Mongolia (0.45 Mt), Russia (0.22 Mt), South Africa (0.13 Mt), Spain (0.12 Mt) and Namibia (0.11 Mt).[16][needs update]
One of the largest deposits of fluorspar in North America is located on the Burin Peninsula, Newfoundland, Canada. The first official recognition of fluorspar in the area was recorded by geologist J.B. Jukes in 1843. He noted an occurrence of “galena” or lead ore and fluoride of lime on the west side of St. Lawrence harbour. It is recorded that interest in the commercial mining of fluorspar began in 1928 with the first ore being extracted in 1933. Eventually, at Iron Springs Mine, the shafts reached depths of 970 feet (300 m). In the St. Lawrence area, the veins are persistent for great lengths and several of them have wide lenses. The area with veins of known workable size comprises about 60 square miles (160 km2).[17][18][19]
In 2018, Canada Fluorspar Inc. commenced mine production again[20] in St. Lawrence; in spring 2019, the company was planned to develop a new shipping port on the west side of Burin Peninsula as a more affordable means of moving their product to markets,[21] and they successfully sent the first shipload of ore from the new port on July 31, 2021. This marks the first time in 30 years that ore has been shipped directly out of St. Lawrence.[22]
Cubic crystals up to 20 cm across have been found at Dalnegorsk, Russia.[23] The largest documented single crystal of fluorite was a cube 2.12 meters in size and weighing approximately 16 tonnes.[24]
Fluorite on barite from the Berbes mine, Ribadesella, Asturias (Spain). Fluorite crystal, 2.2 cm.
In Asturias (Spain) there are several fluorite deposits known internationally for the quality of the specimens they have yielded. In the area of Berbes, Ribadesella, fluorite appears as cubic crystals, sometimes with dodecahedron modifications, which can reach a size of up to 10 cm of edge, with internal colour zoning, almost always violet in colour. It is associated with quartz and leafy aggregates of baryte. In the Emilio mine, in Loroñe, Colunga, the fluorite crystals, cubes with small modifications of other figures, are colourless and transparent. They can reach 10 cm of edge. In the Moscona mine, in Villabona, the fluorite crystals, cubic without modifications of other shapes, are yellow, up to 3 cm of edge. They are associated with large crystals of calcite and barite.[25]
“Blue John”
Main article: Blue John (mineral)
One of the most famous of the older-known localities of fluorite is Castleton in Derbyshire, England, where, under the name of “Derbyshire Blue John”, purple-blue fluorite was extracted from several mines or caves. During the 19th century, this attractive fluorite was mined for its ornamental value. The mineral Blue John is now scarce, and only a few hundred kilograms are mined each year for ornamental and lapidary use. Mining still takes place in Blue John Cavern and Treak Cliff Cavern.[26]
Recently discovered deposits in China have produced fluorite with coloring and banding similar to the classic Blue John stone
