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Class: Halides
Group: Fluorite

An accessory mineral in granite, granite pegmatites, syenites; around fumaroles; in carbonatites and alkaline intrusives. Economic deposits in low- to high-temperature hydrothermal veins and stratabound deposits; a cement in sandstones (Anthony et al., 2001—2005). There are faceted specimens over 3900 carats (Arem, 1987: 99).
Fluorite — specimen 0138
Fluorite — specimen 0138, photo © NMNHS

Original description: unknown.

Type locality: Jáchymov (St Joachimsthal), Ostrov, Krušné Hory Mountains, Karlovy Vary Region, Bohemia, Czech Republic and Breitenbrunn, Breitenbrunn District, Erzgebirge, Saxony, Germany.

Type material: unknown.

Etymology: from the Latin to flow, in allusion to its low melting point.

Distribution: notable localities include: Canada: British Columbia, near Grand Forks, Rock Candy mine; Ontario, Madoc; China: Hunan Province, Xianghuapu; England: from many localities in Cornwall; in Durham, as at Weardale; from Castleton, Derbyshire; France: at Bex, Var; on Mont Blanc, near Chamonix, Haute-Savoie; Germany: Wölsendorf, Bavaria, and in the Clara mine, near Oberwolfach, Black Forest; Kazakhstan: Kara Oba; Mexico: from Naica, Chihuahua; and the Ojuela mine, Mapimí, Durango; Namibia: Okorusu; Pakistan: Gilgit district, near Karimabad, at Nagar; Peru: Huanuco, Huanzala; Russia: Dalnegorsk, Nikolaev mine; Spain: Asturias Province, around Berbes; Switzerland: Uri; USA: Colorado, San Juan Co., Sunnyside mine; Illinois, Hardin Co., Rosiclare and Cave-in-Rock; New Mexico, Grant Co., Burro Mountains, Pine Canyon deposit; New York, Monroe Co., Penfield and St. Lawrence Co., Macomb; Ohio, Ottawa Co., Clay Center; Tennessee, Smith Co., Elmwood mine (Anthony et al., 2001—2005).



Essential elements: fluorine (F), calcium (Ca).

Crystal data

Crystallography: isometric — hexoctahedral. Crystal habit: cubes, octahedra, rarely dodecahedra, or combinations, with many other forms; rounded or stepped, to 2 m; nodular, botryoidal, rarely columnar or fibrous; granular, massive. Twinning: common on {111}, interpenetrant, flattened (Anthony et al., 2001—2005).

Physical properties

Cleavage: {111}, perfect (Anthony et al., 2001—2005). Fracture: subconchoidal to uneven (Anthony et al., 2001—2005). Tenacity: brittle (Anthony et al., 2001—2005). Hardness: 4 (Arem, 1987: 99). Density: 3—3.25 g/cm3 (Lazzarelli, 2012). Luminescence: fluoresces blue, violet, green, yellow, red under UV; may also be phosphorescent; may be thermoluminescent, or triboluminescent (Anthony et al., 2001—2005). Other: slightly soluble in water (0.016 grams per litre at 18°).

Optical properties

Colour: colourless, white, purple, blue, green, yellow, orange; red, pink, brown, bluish black; commonly zoned (Anthony et al., 2001—2005). Diaphaneity: transparent to translucent (Anthony et al., 2001—2005). Lustre: vitreous, dull (Anthony et al., 2001—2005). Refractive index: 1.432—1.436 — isotropic (Lazzarelli, 2012). Dispersion: very low — 0.007 (Arem, 1987: 99). Pleochroism: none.

Material from ‘Repository’

2 specimens: 0137 — 3.87 ct, Brazil; 0138 — 3.86 ct, Brazil.

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