Fluorapatite

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Formula: Ca₅(PO₄)₃F
Anhydrous phosphate containing halogen, apatite group, apatite supergroup
Epitaxial minerals: rutile, monazite and carbonate-rich apatite (Mindat)
Crystal System: Hexagonal
Specific gravity: 3.1 to 3.25 measured, 3.18 calculated
Hardness: 5
Streak: White
Colour: Colourless, yellow, green, blue and purple. Manganoan varieties are dark green and blue-green
Luminescence: Fluorapatite shows some of the widest variation in fluorescence found in the mineral kingdom. Eu²⁺, Eu³⁺, Ce³⁺, Mn²⁺, Dy³⁺, Nd³⁺, Sm³⁺ and Sm²⁺ are the dominant activators of the luminescence; lead and antimony are common coactivators with Mn²⁺, and other substituents such as (Fe²⁺ and Fe³⁺), cobalt and nickel can act as luminescence quenchers. Combinations of different activators, coactivators, and quenching elements, as well as other substituents that distort the fluorapatite structure and shift crystal field interactions, result in the wide range of luminescent colours and intensities found in fluorapatite. Furthermore, different wavelengths of ultraviolet light may elicit different fluorescent responses from the same specimen. Spatial variations of activators, coactivators, and quenching elements lead to zoning in fluorapatite fluorescence (R&M 97.1.36-47, 96,1,20-23).
Solubility: Slightly soluble in sulphuric acid and moderately soluble in hydrochloric and nitric acids
Common impurities: OH,Cl,TR,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Y,Er,Mn
Environments

Igneous environments
Pegmatites
Carbonatitess
Sedimentary environments
Metamorphic environments
Hydrothermal environments

Fluorapatite is the most common rock-forming phosphate mineral.
It occurs as an accessory in all types of igneous rocks, and is important in syenite, alkaline rocks, carbonatites and granite pegmatites. It also occurs in magnetite deposits, and is common in marble and skarn, alpine-type fissures and hydrothermal tin veins. It occurs in both regional and contact metamorphosed rocks, especially crystallised limestone associated with titanite, zircon, pyroxene, amphibole, spinel, vesuvianite and phlogopite, also in talc and chlorite schist, as deposits of marine origin, as replacent beds of limestone or coral via solutions derived from guano, as nodules disseminated in nearshore sediments and in coal measures. It is an essential component of sedimentary phosphorite, common as a detrital or diagenetic component in oolitic ironstone and phosphatic carbonate rocks and shale, and residual in laterite (Dana, HOM).
Other associated minerals include albite, diopside, forsterite, scapolite, chondrodite, calcite and magnetite (HOM, Mindat).

Fluorapatite is usually fluorescent under long or short wave ultraviolet, cathode or X radiation, yellow under long wave and bright orange-yellow under shart wave. The most common activator is Mn²⁺ (FLM). Some fluorapatite from the Foote mine, Kings Mountain, North Carolina, US, is green, near-opaque and exhibits strong yellow fluorescence due to high abundance of Mn²⁺ (R&M 91-3:253).

Localities

There are three co-type localities, the Minillas Mine, Tambillos mining district, La Serena, Elqui Province, Coquimbo, Chile, the Sauberg Mine, Ehrenfriedersdorf, Erzgebirgskreis, Saxony, Germany and the Holmbush Mine, Callington United Mines, Stokeclimsland, Cornwall, England, UK.

At the Broken Hill district, Yancowinna county, New South Wales, Australia, the deposit originally formed in a shallow lake or submarine rift and now comprises an intensely granulite and upper amphibolite facies metamorphosed and deformed sequence of sedimentary and volcanic rocks, and minor iron-rich and calc-silicate layers. Quartz-feldspar gneiss probably originated from felsic volcanic rocks and associated granitic intrusions, while amphibolites reflect metamorphosed mafic magmas originally emplaced as flows and associated intrusions. Subaqueous hydrothermal precipitation involving ore fluids from crustal, magmatic, evaporitic, and possibly lacustrine sources produced metal-rich deposits. Prolonged oxidation and weathering of the sulphide-rich orebodies in the near-surface environment produced a zone greatly enriched in silver and lead and many attractive, well-crystallised secondary minerals. This oxidised zone has long been removed by mining; current operations access the deeper, primary sulphide-rich orebodies.
Specimens of fluorapatite from the primary ore are more common, generally larger, and more aesthetic than those from secondary assemblages and late-stage fractures. Within the primary ore, the fluorapatite occurs in two major associations: one in which fluorapatite is associated with sulphides such as galena and sphalerite, rhodonite and spessartine but lacking significant amounts of calcite or fluorite; in the other fluorapatite occurs with abundant calcite and/or fluorite. Vitreous, lustrous and translucent greenish-blue fluorapatite occurs as small (typically a few millimeters), squat, rounded grains in sulphides, usually galena. Rhodonite, spessartine, and less commonly sphalerite and chalcopyrite also occur. Rarer specimens have prismatic, brown, translucent fluorapatite crystals up to a few centimeters long embedded in galena. The largest Broken Hill fluorapatite crystals are typically several centimeters in length and occur in association with calcite and/or fluorite. These crystals are typically vitreous, lustrous, opaque, dark bluish-green or greyish-green, and they are commonly fractured, bent, and sometimes broken and slightly displaced with the gap infilled with granular calcite. Thin slivers of the fluorapatite are translucent and pale bluish-green. Fluorite tends to be granular and occurs in patches that give the appearance of a poorly defined fabric. Bustamite and hedenbergite also may be present. Fluorite, bustamite and calcite may occur as inclusions in fluorapatite crystals. The most common associate in the fluorapatite-calcite assemblage is a pale pinkish-brown fluorite. Other specimens contain colourless fluorite, and in both cases the fluorite is readily identified by its blue fluorescence under longwave ultraviolet light.
Fluorapatite also occurs in other but rare associations in the Broken Hill orebody. These include pale bluish-grey fluorapatite associated with either gemmy crystals of pink bustamite and minor calcite, hedenbergite and galena, or associated with calcite, bustamite, quartz, and minor galena and sphalerite. A small, very pale green fluorapatite from the NBHC mine and associated with bannisterite has been found. There are two unusual fluorapatite specimens purportedly coming from Broken Hill. One consists of an aggregate of pale green, granular fluorapatite, and the other specimen has pale bluish, granular fluorapatite in a honeycomb-like siliceous matrix. Another unusual specimen consists of a well-formed, pale greenish-yellow crystal associated with chamosite from the Zinc Corporation mine.
The vast majority of fluorapatite specimens from Broken Hill that were examined under UV light are unresponsive or fluoresce a dull yellow-orange, orange-red or blueviolet. One exception to this observation, however, is a specimen with fluorapatite enclosed in galena that fluoresces a bright yellow. This fluorescence possibly is caused by Mn²⁺ substituting for P (R&M 97.1.16-26).

At Klemm's quarry, Moculta, South Australia, fluorapatite crystals to 3mm have been found scattered on mitridatite (AJM 17.1.16-17).

The Lake Boga granite, Lake Boga, Swan Hill Rural City, Victoria, Australia, is a very large intrusion formed about 365 million years ago. The entire outcrop of the granite is overlain by sediments in places up to several hundred meters thick. The sole exposure into the granite is the Lake Boga quarry, where the sediment is only a few metres thick. The uppermost levels of the granite exhibit aplite veins, pods of pegmatite, and numerous miarolitic cavities, features that are characteristic of the uppermost levels of a granite magma intruded to shallow crustal levels.
Fluorapatite crystals were relatively common in the miarolitic cavities and pegmatite patches before they were quarried out. Smoky quartz, orthoclase-microcline, albite, muscovite and schorl are common associates. The crystals are generally well-formed, ranging from tabular to blocky, less commonly prismatic; prism faces are almost always striated. Some larger crystals have a thin coating of drusy quartz and feldspar. The most common colour of the fluorapatite is dull greyish-green to bluishgreen, but the largest and most spectacular crystals are deep blue. Most large crystals show colour zoning that may involve dark and pale blue, green, purple, lilac or colourless zones.
Lake Boga fluorapatite crystals contain small amounts of manganese, strontium and uranium, that are responsible for the observed colour zonation, interpreted to represent episodes of continuous or interrupted growth. The uranium concentration is significantly greater than in most fluorapatite in granites and granitic pegmatites throughout Australia.
The fluorapatite crystals contain a variety of inclusions; uraninite is the most abundant, and monazite-(Ce), cheralite-(Ce) and allanite-(Ce) inclusions also occur (R&M 97.1.28-32).

At Llallagua, Bolivia, fluorapatite occurred as a gangue mineral in cassiterite veins. Fluorapatite crystals have been found on quartz and ferberite crystals in many vugs. Most fluorapatite is covered by a crust of wavellite. Some crystals occur on a stannite matrix associated with jeanbandyite. Crystals filled with fine jamesonite needles have also been found (Min Rec 37-2.134).

In the Bancroft area, Ontario, Canada, fluorapatite crystals up to 45 cm long have been found in the calcite vein-dikes (R&M 94.5.412) .

At the poudrette quarry, Mont Saint-Hilaire, Quebec, Canada, fluorapatite is exceptionally high in thorium content (R&M 95.2.164-165).

At Girardville, Quebec, Canada, fluorapatite is rare in the calcite-carbonatite vein. Typical parageneses include phlogopite, ilmenite, orthoclase and aegirine (R&M 88-5.431).

At the Yates Prospect, Otter Lake, Quebec, Canada, it appears that fluorapatite is a primary mineral that crystallised from a carbonate melt (R&M 94.3.274-275).

At the Wutong mine, Guangxi, China, fluorapatite is intimately associated with rhodochrosite and fluorite (Min Rec 42-6.540).

At Yaogangxian, Hunan, China, fluorapatite is associated with arsenopyrite, bournonite, boulangerite, stannite, ferberite, chalcopyrite, quartz and fluorite (Min Rec 42-6.580-581 ).

The Bairendaba Ag-polymetallic deposit, Hexigten Banner, Chifeng City, Inner Mongolia, China, is a mesothermal magmatic-hydrothermal vein-type silver - lead - zinc deposit, hosted in Hercynian (about 419 to 299 million years ago) quartz diorite.
It is suggested that, with decreasing temperature, mineral compositions changed progressively from tungstate and oxide, to diatomic sulphide, to simple sulphide, to an antimony sulphosalt mineral, and finally to an antimonide.
Fluorapatite occurs as lustrous, stout, pale blue hexagonal prisms to about 1 cm showing minor pyramidal modifications. Associated minerals include lenticular siderite crystals and deep purple cubic fluorite crystals (Minrec 53.347-359).

At the Monte Cervandone area, Devero Alp, Baceno, Verbano-Cusio-Ossola Province, Piedmont, Italy, excellent specimens of “asparagus stone” (yellow-green fluorapatite) have been collected at a site somewhere on the Swiss side of Monte Cervandone. The crystals are short-prismatic, with diameters to 3 cm, and are associated (unusually for sites in this area) with the fibrous amphiboles “byssolite” and “mountain leather”. In 2005, colourless to pale lilac fluorapatite crystals to 1 cm were found in gneiss clefts in Chummibort (MinRec 56.3.312-314).
Fluorapatite from the Monte Cervandone Area - Image

At Diako, Kayes region, Mali, fluorapatite has been found with epidote and with garnet (Min Rec 42-3.243 ).

At Cerro de Mercado, Durango, Mexico, fluorapatite is found embedded in masses of sepiolite with quartz and chalcedony, and with augite crystals in breccia (Min Rec 42-5.477-484).

Morocco
In Morocco carbonate-rich fluorapatite, also called francolite, is mainly associated with marine sedimentary phosphorites. Morocco contains the world’s largest reserves of phosphorites, our main source of phosphate for fertilisers. The economic deposits are mainly distributed over four basins including Ouled Abdoun, Ganntour, Meskala, and Oued Ed-dahab. In these deposits francolite is the major phosphate mineral, making up to 70 volume percent of the rock. It occurs mainly as spheroidal to elliptical grains from 50 to 500 µm in size (R&M 98.2.173-174).

At Imilchil, Er Rachidia Province, Drâa-Tafilalet, Morocco, fluorapatite is found in hydrothermally altered syenite and nepheline syenite (R&M 90.244-256).

At Anemzi, Imilchil, Er Rachidia Province, Drâa-Tafilalet, Morocco, fluorapatite occurs with a wide range of associated minerals, including microcline, chlorite, magnetite, titanite, actinolite, stilbite, arfvedsonite, calcite, epidote, prehnite, hematite and hedenbergite (R&M 90.244-256).

At Alchuri, Shigar Valley, Northern Areas, Pakistan, fluorapatite occurs on druses of clinozoisite, and commonly on beds of actinolite, and occasionally with diopside or epidote (Min Rec 37-6.535).

At Ekaterinburg, Ural mountains, Russia, fluorapatite occurs in mica schist with beryl variety emerald and chrysoberyl (Dana).

At Palabora, Limpopo Province, South Africa, fluorapatite is a major constituent occurring in some of the cavities, associated with fluoborite and rarely with fluorite (R&M 92.5.438).

At Jumilla, Murcia, Spain, fluorapatite was found in andesite tuff (Dana).

In the Erongo, Namibia, miarolytic cavities fluorapatite is rare, but it has been found as crystals on quartz and schorl (Min Rec 37.5.402).

At the the Karo Mine, Block D, Merelani Hills, Arusha Region, Tanzania, fluorapatite is found which contains fluid inclusions, some of which contain graphite crystals (R&M 88.2.162 and 178-183).

At the Carrock mine, Caldbeck Fells, Cumbria, England, UK, fluorapatite crystals to 3 cm occur on a muscovite and quartz matrix, and crystals embedded in quartz with pyrite have been found (C&S).

At Tyllau Mwyn, Drws-y-nant, Gwynedd, Wales, UK, fluorapatite has been found in stilpnomelane - bearing calcite veins (MW).

At Prenteg, Tremadog, Gwynedd, Wales, UK, fluorapatite forms crystals to 1.5 mm associated with rutile, chamosite and albite (MW).

At the Moiliili Quarry, Honolulu, Oahu, Honolulu county, Hawaii, USA, fluorapatite forms thin, needlelike crystals within cavities of nepheline basalt, associated with augite and nepheline (R&M 92.3.226).

The Pulsifer pegmatite, West Mount Apatite Mining District, Auburn, Androscoggin county, Maine, USA, is a rare-element granitic pegmatite that intrudes upper amphibolite facies metamorphosed clay-rich rocks and biotite schists that are locally interbedded with calc-silicate rocks. The pegmatite exhibits five distinct zonations.
The border zone consists of fine to medium grained equi-granular quartz and plagioclase, and minor biotite and almandine.
The wall zone consists of slightly graphic K-feldspar, quartz, biotite and almandine.
The first intermediate zone is characterised by coarse-grained graphic feldspar and plumose muscovite-quartz aggregates. Almandine and schorl are found as accessory minerals, and rare beryl has been observed.
The first intermediate zone grades irregularly into a coarse-grained plagioclase plus quartz plus muscovite second intermediate zone.
The pocket zone assemblage, which lies below the second intermediate zone and immediately above the garnet seam, consists primarily of cleavelandite and quartz, although locally blocky K-feldspar and muscovite are also abundant. Gem tourmaline, beryl, fluorapatite, hydroxylherderite, gahnite, almandine, columbite-(Mn) and cookeite are among the minerals that have been found within the pocket zone.
The garnet seam is a 1 to 5 cm thick layer of 2 mm to 3 cm euhedral almandine plus anhedral smoky quartz.
Just below the garnet seam lies a zone of undetermined thickness that is composed primarily of blocky graphic albite.
Purple apatite is a rare variety of fluorapatite that is most prevalent in evolved granitic pegmatites. At the Pulsifer pegmatite purple fluorapatite is typically found in small mud-filled pockets within cleavelandite-rich areas immediately above the garnet seam. The crystals typically show colour zoning, with dark purple rims through lighter shades of purple to an almost white core. Fluorescence of Pulsifer purple fluorapatite varies with the shade of purple colour. Under longwave ultraviolet radiation, deep purple-coloured areas display weak orange fluorescence. The intensity of the orange fluorescence increases significantly in pale purple and white portions of the crystals. Cathodoluminescence measurements from a few single crystals and fragments in general showed areas of bright yellow-green cathodoluminescence emission corresponding to pale purple or white parts of the fluorapatite. Portions of the crystals with deep purple colour were only weakly luminescent in the electron beam (R&M 97.1.8-11).

At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, fluorapatite occurs as crystals to 3 cm. The best crystals occur in vugs formed from alteration of beryl and on albite variety cleavelandite and muscovite crystals in miarolytic cavities. The fluorapatite is typically associated with bertrandite, cookeite and Fe/Mn oxides after siderite/rhodochrosite. The Emmons pegmatite is an example of a highly evolved boron-lithium-cesium-tantalum enriched pegmatite (R&M 94.6.507-508).

At Hayes Ledge Quarries, Greenwood, Oxford County, Maine, USA, quite small but also quite sharp, translucent blue-green hexagonal-tabular crystals of fluorapatite have been found, together with miniature-size matrix pieces on which fluorapatite crystals up to 1 cm in size repose on concentrations of silvery muscovite in the pegmatite (MinRec 55.1.83).

At the pegmatite at the Waisanen quarry, Greenwood, Oxford county, Maine, USA, fluorapatite occurs with a druse of quartz prisms and rare oxidised pyrite cubes on etched microcline and occasional muscovite books. In some cases late stage albite appears as an overgrowth on the microcline (R&M 91-2.179-180).

At Acushnet Quarry, Bristol County, Massachusetts, USA, fluorapatite has formed in an Alpine cleft. Hydrothermal fluids, associated with orogenic metamorphism, often deposit characteristic minerals, including apatite, in these clefts. The metamorphic rocks exposed in the Acushnet quarry are a mixture of schist, gneiss and intruded diorite. Fluorapatite is found here on a chlorite-covered matrix, associated with K-feldspar variety adularia, albite variety pericline, calcite, epidote, muscovite, quartz, titanite, chabazite and stilbite (R&M 90.244-256)

At a small beryl-rich unnamed pegmatite at Dickinson county, Michigan, USA, the dike is well zoned with a massive quartz core, surrounded by beryl crystals, fluorapatite and niobium-tantalum species (R&M 90-5.446).

At the Chickering Mine, Walpole, Cheshire county, New Hampshire, USA, fluorapatite is found in cavities that formed by the dissolution of elbaite and, to a lesser extent, by the alteration of spodumene within a quartz matrix (R&M 90-5.416).

At the Keyes Mica Quarries, Orange, Grafton County, New Hampshire, USA, the pegmatites are beryl-type rare-element (RE) pegmatites.
The Number 1 mine exposed a pegmatite that shows the most complex zonation and diverse mineralogy of any of the Keyes pegmatites. Six zones are distinguished, as follows, proceeding inward from the margins of the pegmatite:
(1) quartz-muscovite-plagioclase border zone, 2.5 to 30.5 cm thick
(2) plagioclase-quartz-muscovite wall zone, 0.3 to 2.4 metres thick
(3) plagioclase-quartz-perthite-biotite outer intermediate zone, 0.3 to 5.2 metres thick, with lesser muscovite
(4) quartz-plagioclase-muscovite middle intermediate zone, 15.2 to 61.0 cm thick
(5) perthite-quartz inner intermediate zone, 0.9 to 4.6 meters thick
(6) quartz core, 1.5 to 3.0 metres across
The inner and outer intermediate zones contained perthite crystals up to 1.2 meters in size that were altered to vuggy albite-muscovite with fluorapatite crystals. This unit presumably was the source of the albite, muscovite, fluorapatite, quartz and other crystallised minerals found in pieces of vuggy albite rock on the dumps next to the mine.
The middle intermediate zone produced sheet mica with accessory minerals including tourmaline, graftonite, triphylite, vivianite, pyrite, pyrrhotite, and beryl crystals to 30.5 cm long and 12.7 cm across.
The white apatite from the Keyes mines differs in composition and other properties from the coloured varieties, and is considered to be carbonate-rich fluorapatite. It occurs in a variety of habits and associations. One specimen is a tangled porous cluster of many straight to slightly curving fluorapatite “sticks”, each about 2 mm across and up to 4 cm long, together with a few rusted microsized pyrite cubes. Another specimen has white carbonate-rich fluorapatite crystals with the stick habit overlain by colourless to milky quartz crystals. Other white fluorapatites in the vuggy albite suite at the Keyes mines include sharp crystals to 4 mm across, tiny spheres, and rosettes with muscovite. All these white varieties fluoresce cream-yellow under shortwave ultraviolet light.
For the coloured varieties, most specimens came from the vuggy albite replacement unit at the No. 1 mine, but some are known from Nos. 2 and 4. Keyes coloured fluorapatite crystals may be green, blue-green, blue, purple or grey. Some crystals are concentrically zoned, usually with purple exteriors and green cores. One specimen is known with a rare white-over-green zonation. Associated minerals include bertrandite, muscovite and albite. Most of the Keyes fluorapatites are less than 15 mm long, but a few reach 3 cm. The blue-green and white crystals commonly fluoresce cream-white to yellow under shortwave UV, but it appears that the purple crystals do not fluoresce (R&M 97.4.315-316).

At the Adirondack mountains, New York, USA, fluorapatite occurs with with magnetite (Dana).

Amity, Town of Warwick, Orange county, New York, USA, is an area of granite intrusions into marble and associated gneiss. The marble is mostly composed of white crystalline calcite that often has small flakes or spheres of graphite and phlogopite. Fluorapatite is found as large pale blue crystals to 10 cm in length, often associated with augite (R&M 96.5.436).

At the tourmaline locality at Gouverneur, St. Lawrence county, New York, USA, fluorapatite occurs rarely, with diopside and tremolite in pockets in calc-silicate rock (R&M 91.6.523).

At the Harder farm, Hammond, St Lawrence county, New York, USA, fluorapatite occurs in calcite (R&M 85.5.461).

At The Dafoe Property, Pierrepont, St Lawrence county, New York, USA, fluorapatite occurs abundantly on the surfaces of some tourmaline crystals (R&M 94.5.452-455).

At Rose Road, Pitcairn, St. Lawrence county, New York, USA, fluorapatite occurs as prismatic crystals ranging in colour from green to blue to vivid blue. The strength and colour of fluorescence roughly correlates with the colour in visible light. Vivid blue crystals fluoresce brilliant blue-white. Other fluorapatite crystals fluoresce less brightly with colours ranging from a dull blue through yellow to a dull white (R&M 97.5.441).

The Purple Diopside Mound, Rose Road, Pitcairn, St. Lawrence county, New York, USA, is situated in marble. The development of veins of large crystals probably occurred as a result of fluid penetration from a concurrent intrusion. Many of the minerals of interest to collectors formed during this primary event, with additional species resulting from the subsequent alteration of scapolite. Fluorapatite is uncommon but shows a strong yellow fluorescence under short wave UV against a background of nonfluorescent calcite (R&M 97.5.443).

At the Foote Mine, Kings Mountain, North Carolina, USA, fluorapatite is found as masses and crystals in unaltered spodumene-bearing pegmatites, and also as a hydrothermal mineral along fractures and in solution cavities throughout the pegmatites and surrounding country rocks. In the primary stage of mineralisation microcline, quartz and spodumene crystallised from the melt, with accessory fluorapatite, chlorite, muscovite, and pyrrhotite. The second stage was the hydrothermal alteration of the primary pegmatite minerals included leaching of elements and their enrichment in the hydrothermal fluids. The third stage was the precipitation of secondary phosphate and silicate minerals, the most abundant of which was fluorapatite. Fluorapatite is most commonly found with albite, fairfieldite and bikitaite (R&M 91-3.250-256).

At South Foster, Providence county, Rhode Island, USA, fluorapatite crystals have been found in a road cutting at the white schoolhouse on the hill just west of the town. They are developed along a contact line between fine grained granite and a small mass of crystalline limestone, in small open cavities associated with biotite and scapolite (AM7.28)

At the Clay Canyon variscite mine, Fairfield, Utah, USA, fluorapatite has been found as microcrystals in cavities cementing fragments of crandallite (Min Rec 41-4.338).

At the Belvidere Mountain Asbestos Quarries, Lowell/Eden, Vermont, USA, fluorapatite is fairly common in schist and gneiss. It occurs locally in the chlorite rock, and in the amphibolite it sporadically occurs as a relict mineral (R&M 90-6.533).

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