Fluoroapatite

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Fluoroapatite
Fluorapatite HMNH1.jpg
Double ended crystal in calcite from Quebec, Canada
General and classification
other names

formerly apatite (CaF)

chemical formula Ca 5 [F | (PO 4 ) 3 ]
Mineral class
(and possibly department) 		Phosphates, arsenates, vanadates - anhydrous phosphates with foreign anions
System no. to Strunz
and to Dana 		8.BN.05 ( 8th edition : VII / B.39)
08/41/01/01
Similar minerals other apatites
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol hexagonal dipyramidal; 6 / m
Room group (no.) P 6 3 / m (No. 176)
Lattice parameters a  = 9.40  Å ; c  = 6.88 Å
Formula units Z  = 2
Frequent crystal faces {10 1 0}, {0001}, {10 1 1}
Physical Properties
Mohs hardness 5
Density (g / cm 3 ) 3.2
Cleavage indistinct
Break ; Tenacity shell-like, brittle
colour colorless, white, yellow, pink, blue, violet, green, brown
Line color White
transparency transparent to translucent
shine Glass gloss, fat gloss, matt
radioactivity contains traces of uranium and other rare earths
Crystal optics
Refractive indices n ω  = 1.631 to 1.650
n ε  = 1.627 to 1.646
Birefringence δ = 0.004
Optical character uniaxial negative
Pleochroism green apatite slightly yellow, blue apatite very strong blue and colorless
Other properties
Chemical behavior soluble in hydrochloric and nitric acid
Special features Fluorescence and phosphorescence , especially in manganese-containing varieties

Fluorapatite (formerly apatite (CaF) ) is a very common and rock-forming mineral from the mineral class of " phosphates , arsenates and vanadates " and the most common of all apatites . It crystallizes in the hexagonal crystal system with the chemical composition Ca 5 [F | (PO 4 ) 3 ] and occurs both in the form of different colored crystals and large, massive mineral aggregates and as a component in teeth .

Etymology and history

Violet fluorapatite from the type locality Greifensteine ​​(field of view 12 mm)

The name fluorapatite indicates, on the one hand, its close relationship and chemical similarity with the other members of the apatite group and, on the other hand, the element fluorine, which is decisive in its chemical composition .

The mineral was named in 1827 by Gustav Rose (1798–1873). The type locality is the Greifensteine near Ehrenfriedersdorf in the Saxon Ore Mountains.

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the fluoroapatite belonged to the mineral class of "phosphates, arsenates, vanadates" and there to the department of "anhydrous phosphates with foreign anions ", where together with Belovit- (Ce) , Belovit- (La) , carbonate-fluoroapatite ( carbonate-apatite- (CaF) ), carbonate-hydroxylapatite ( carbonate-apatite- (CaOH) ), chlorapatite ( apatite- (CaCl) ), Fermorite , fluorocaphite , hedyphan , hydroxylapatite ( apatite (CaOH) ), Johnbaumit , Klinomimetesit , Kuannersuit- (Ce) , Mimetesit , Morelandit , Pyromorphit , strontium apatite , Svabit , Turneaureit and Vanadinit the stand-alone "apatite Pyromorphit group" with the system number. VII / B.39 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns fluoroapatite to the class of "phosphates, arsenates and vanadates" and there to the department of "phosphates, etc. with additional anions ; without H 2 O “. However, this section is further subdivided according to the size of the cations involved and their molar ratio to the phosphate, arsenate or vanadate complex RO 4 , so that the mineral according to its composition is classified in the subsection “With only large cations; (OH etc.): RO 4  = 0.33: 1 “can be found where it is found together with Alforsit , Belovit- (Ce), Belovit- (La), carbonate-fluoroapatite, carbonate-hydroxyapatite, chlorapatite, fluorostrophite, hydroxyapatite , Hydroxylapatit-M, Deloneit- (Ce), Fermorit, Fluorcaphit, Hedyphan, Hydroxyl-Pyromorphit, Johnbaumit, Klinomimetesit, Kuannersuit- (Ce), Mimetesit, Morelandit, Phosphohedyphan , Pyromorphit, Svabit, Turneaureit, Vanadinit the "Apatit" Group "with the system no. 8.BN.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the fluoroapatite to the class of "phosphates, arsenates, vanadates" and there to the category of "anhydrous phosphates, etc., with hydroxyl or halogen". Here it is together with chlorapatite, hydroxylapatite, carbonate-fluorapatite, carbonate-hydroxylapatite, Belovit- (Ce), Belovit- (La), Kuannersuit- (Ce), fluorostrophite, fluorocaphite, Deloneit- (Ce), stronadelphite, fluorophosphohedyphane and phosphohedyphane in the "apatite group" with the system no. 41.08.01 to be found within the subsection of " Anhydrous phosphates etc., with hydroxyl or halogen with (A) 5 (XO 4 ) 3 Z q ".

Crystal structure

Unit cell of fluorapatite

Fluorapatite crystallizes hexagonally in the space group P 6 3 / m (space group no. 176) with the lattice parameters a  = 9.40  Å and c  = 6.88 Å and 2 formula units per unit cell .

properties

Especially in the case of manganese-containing varieties, fluorescence or thermoluminescence and phosphorescence show under UV light and after heating .

Before the soldering tube , the mineral is very difficult to melt and forms a colorless, glass-like pearl. Together with phosphorus salt, an unclear, faceted pearl is created when it cools in an unsaturated solution and, when completely saturated, a milk-white pearl. In soda it swells under a shower and, when moistened with sulfuric acid , it turns the soldering tube flame greenish. In addition, fluoroapatite is soluble in hydrochloric and nitric acid .

Education and Locations

Pink fluorapatite on muscovite from Chumar Bakhoor in the Hunza Valley , Pakistan (size: 7.6 cm x 6.2 cm x 4.6 cm)
Blue, perfectly formed fluoroapatite from São Geraldo do Baixio, Doce valley, Minas Gerais , Brazil

Fluorapatite is one of the most common rock-forming phosphate minerals and is found as an accessory component in most volcanic rocks and as an important component of syenites , alkaline rocks, carbonatites and granitic pegmatites . In metamorphic rocks such as marble and skarn and in hydrothermal veins of tin - deposits can be found fluorapatite. Accompanying minerals include calcite , chondrodite , diopside , forsterite , magnetite , phlogopite and scapolite .

In total, fluorapatite has so far (as of 2011) been detected at around 2120 sites. In addition to its type locality Greifensteine , the mineral occurred in Germany in other places in the Ore Mountains , Upper Lusatia and Vogtland as well as near Penig in Saxony; in several places in the Black Forest , at the Kaiserstuhl and Katzenbuckel in Baden-Württemberg; in many places in Franconia , the Bavarian Forest and the Upper Palatinate as well as on the Nördlinger Ries in Bavaria; in the Sauerland and Siebengebirge in North Rhine-Westphalia; in many places in the Eifel as well as in the Hunsrück , in the Taunus and in the Westerwald in Rhineland-Palatinate as well as at some sites in Hesse , Lower Saxony , Saarland , Saxony-Anhalt , Schleswig-Holstein and Thuringia .

In Austria, the mineral was among others on Pauliberg in Burgenland; in the Gurktal Alps in Carinthia; the Hohe Tauern from Carinthia to Salzburg; near Statzendorf , Rossatz-Arnsdorf and in the Waldviertel in Lower Austria; the Radstädter Tauern and in the Tamsweg district in Salzburg; at some sites in Styria , Tyrol and Upper Austria as well as in the Bregenzerwald in Vorarlberg.

In Switzerland, fluorapatite was mainly found in the cantons of Graubünden , Ticino , Uri and Valais . Fiesch in the Swiss canton of Valais, where crystals with a diameter of up to 10 cm were found, is worth mentioning because of the extraordinary finds of fluorapatite .

Large deposits of massive fluoroapatite became known on the Russian Kola Peninsula , from which crystal blocks weighing up to 300 kg were extracted.

Other locations are Afghanistan , Egypt , Antarctica , Argentina , Australia , the Bahamas , Belgium , Bolivia , Brazil , Chile , China , the Democratic Republic of the Congo , Finland , France , Gabon , Greenland , Guinea , India , Iran , Israel , Italy , Japan , Yemen , Jordan , Cambodia , Canada , Kazakhstan , Kenya , Kyrgyzstan , Colombia , North and South Korea , Libya , Madagascar , Morocco , Mexico , Mongolia , Mozambique , Myanmar , Namibia , New Zealand , Norway , Pakistan , Palestine , Peru , Poland , Portugal , Rwanda , Romania , Russia , Zambia , Saudi Arabia , Sweden , Senegal , Zimbabwe , Slovakia , Spain , South Africa , Sri Lanka , Tajikistan , Tanzania , Czech Republic , Tunisia , Turkey , Uganda , Hungary , the Ukraine , Uzbekistan , Venezuela , the United Kingdom (Great Britain), the United States of America (USA) and Vietnam .

Fluoroapatite could also be detected in rock samples from the Pacific Ocean , more precisely from the seabed on the southern coast of California and outside the earth on the moon near the landing bases of Luna 24 , Apollo 11 and Apollo 14 .

Biological synthesis

In enamel fluorapatite created for. B. when hydroxyapatite, which is also a component of human teeth, is treated with substances containing fluoride (for example fluoride toothpaste); it is more acid-resistant than hydroxyapatite.

Reaction equation:

See also

Individual evidence

  1. ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 466 .
  2. ↑ Webmineral - Apatite- (CaF) (English)
  3. ↑ a b c d Fluorapatite at mindat.org (engl.)
  4. ↑ G. Rose: About the chemical composition of apatites. In: Ann. Phys. Volume 9, 1827, pp. 185-214; (P. 196: "Let's call the former chlorapatites, the latter fluoroapatites ...")
  5. ↑ CF Rammelsberg: Apatite . (PDF; 234 kB). In: Handbuch der Mineralchemie. Wilhelm Engelmann, Leipzig 1860, pp. 351–355.
  6. ↑ Handbook of Mineralogy - Fluorapatite (English, PDF 67 kB)
  7. ↑ Mindat - Localities for fluorapatite

literature

  • Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 170 .

Web links

Commons : Fluorapatite  - Collection of images, videos and audio files