Heterosity
| Heterosity | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Fe 3+ [PO 4 ] |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.AB.10 ( 8th edition : VII / A.02) 04/38/01/01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Space group | Pbnm (No. 62, position 3) |
| Lattice parameters | a = 4.77 Å ; b = 9.79 Å; c = 5.83 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 4 to 4.5 |
| Density (g / cm 3 ) | measured: 3.40; calculated: [3.67] |
| Cleavage | good after {100}; indistinct after {010} |
| colour | purple-pink, violet, greenish-brown, black |
| Line color | purple to brownish red |
| transparency | translucent to opaque |
| shine | Satin gloss, matt |
| Crystal optics | |
| Refractive indices |
n α = 1.861 (1) n β = 1.891 (1) n γ = 1.911 (1) |
| Birefringence | δ = 0.050 |
| Optical character | biaxial negative |
| Axis angle | 2V = 37 ° (measured) |
| Pleochroism | strong: X = greenish gray, gray to pinkish red Y, Z = deep blood red to red violet Z = deep blood red to red violet |
Heterosite is a rather seldom occurring mineral from the mineral class of “ phosphates , arsenates and vanadates ” with the idealized composition Fe 3+ [PO 4 ] and is therefore chemically iron (III) phosphate . Since heterosite forms a complete mixed crystal row with purpurite (Mn 3+ [PO 4 ]) and is therefore always found in nature with a certain proportion of manganese in the compound, the formula of heterosite is generally also used with (Fe 3+ , Mn 3+ ) [PO 4 ].
Heterosite crystallizes in the orthorhombic crystal system , but does not form any visible crystals. Like its cousin purpurite, heterosite is usually found in the form of granular to massive aggregates from purple-pink to purple, rarely also greenish-brown in color. The surfaces of fresh samples usually have a silky sheen . Over time, weathering can cause the color to turn from dark brown to brownish black and the surfaces become matt.
Etymology and history
Heterosite was first discovered at Les Hureaux near the commune of Saint-Sylvestre in the French department of Haute-Vienne . It was scientifically described in 1825 by François Alluaud (1778–1866), who named the mineral after the Greek word ἕτερος [heteros] for “deviant”. Alluaud himself gave no reason for the chosen name. Since, however, at the same time he described a further, secondary manganese-iron-phosphate from the same type locality and obviously named after this as Hureaulite ((Mn, Fe) 5 [(PO 3 OH) 2 | (PO 4 ) 2 ] · 4H 2 O) , it is assumed that he named the heterosite based on its different chemical composition.
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of heterosite to general ward belonged "water clear phosphates without foreign anions " where he along with Ferrisicklerit , Lithiophilit , Marićit , Natrophilit , Purpurit , Sicklerit , Simferit and triphylite the unnamed group VII / A.02 formed.
The 9th edition of Strunz's mineral systematics , which has been in force since 2001 and is used by the International Mineralogical Association (IMA), also assigns heterosite to the category of “phosphates etc. without additional anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With medium-sized cations”, where it can be found together with ferrisicklerite, lithiophilite, natrophilite, purpurite, sicklerite, simferite and triphylin "Triphyline group" with the system no. 8.AB.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns heterosite to the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates etc.". Here it can only be found together with Purpurit in the unnamed group 38.04.01 within the subdivision of " Anhydrous phosphates etc., A + XO 4 ".
Crystal structure
Heterosite crystallizes orthorhombically in the space group Pbnm (space group no. 62, position 3) with the lattice parameters a = 4.77 Å ; b = 9.79 Å and c = 5.83 Å and 4 formula units per unit cell .
Education and Locations
Heterosite formed as Purpurit predominantly secondarily as a crust-forming oxidation product from triphylite (LiFe [PO 3 ]) or Lithiophilit (LiMn [PO 3 ]). It can rarely also arise primarily in the form of granular masses in granitic pegmatites . In addition to triphyline or lithiophilite, ferrisicklerite and many other secondary phosphate minerals occur as accompanying minerals .
As a rather rare mineral formation, heterosite can sometimes be abundant at different sites, but overall it is not very common. Around 190 sites are known to date (as of 2012). In addition to its type locality Les Hureaux, the mineral appeared in France in several places near Razès , near Montesquieu-des-Albères (Pyrénées-Orientales), as well as Auzat ( Ariège department ) and in the Vallée d'Aure ( Hautes-Pyrénées department ) .
In Germany, heterosity has so far only been found in Bavaria, more precisely on the Hennenkobel ( Hühnerkobel ) and on the Pauliberg near Zwiesel , in several places near Hagendorf ( Waidhaus ) and near Pleystein in the Upper Palatinate Forest .
In Austria, the mineral was found in a spodumene test mining on the back of the fire (see also Mining in Carinthia ) and near the Laggerhof on Lake Millstatt and near Wolfsberg in Carinthia .
The only known site in Switzerland so far is the Pontetal near Brissago TI in the canton of Ticino.
Other locations are in Angola, Argentina, Australia, Bolivia, Brazil, Finland, Italy, Kazakhstan, Madagascar, Morocco, Namibia, Poland, Portugal, Rwanda, Sweden, Spain, South Africa, South Korea, the Czech Republic and the United States of America ( UNITED STATES).
See also
literature
- F. Alluaud: Notices sur l'hétérosite, l'hureaulite (fer et manganèse phosphatés), et sur quelques autres minéraux du département de la Haute-Vienne , in: Anneles des Sciences Naturelles , Volume 8 (1826), p. 334– 354 ( PDF 703.3 kB , French)
Web links
Individual evidence
- ↑ a b c d e f 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. 427 .
- ↑ a b c Heterosite , in: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ([PDF kB])
- ↑ a b c d e f g Mindat - Heterosite
- ^ Helmut Schrätze, Karl-Ludwig Weiner: Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 612 .
- ^ 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. 474 .
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp. 623 (first edition: 1891).
- ↑ Mindat - Number of localities for heterosity