Trollit

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Trollit
Trolleite w- berlinite and scorzalite Hydrous aluminum phosphate Harrsjoberg Vermland Sweden 1888.jpg
General and classification
chemical formula Al 4 [OH | PO 4 ] 3
Mineral class
(and possibly department) 		Anhydrous phosphates with foreign anions
System no. to Strunz
and to Dana 		8.BB.45 ( 8th edition : VII / B.08)
11.11.01.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group
Lattice parameters a  = 18.894  Å ; b  = 7.161 Å; c  = 7.162 Å
β  = 99.99 °
Formula units Z  = 4
Physical Properties
Mohs hardness 5.5 to 6
Density (g / cm 3 ) 3.1
Cleavage Please complete!
colour colorless, pale blue, pale green
Line color White
transparency translucent
shine Glass gloss, fat gloss
Crystal optics
Refractive indices n α  = 1.619
n β  = 1.639
n γ  = 1.643
Birefringence δ = 0.024
Optical character biaxial negative
Axis angle 2V = 49 °

Trolleite is a rather seldom occurring mineral from the mineral class of phosphates . It crystallizes in the monoclinic crystal system with the chemical composition Al 4 [OH | PO 4 ] 3 and develops predominantly massive to flaky aggregates that are either colorless or pale blue to pale green in color.


Etymology and history

The mineral was first described in 1868 by Christian Wilhelm Blomstrand (1826–1897), who named it “Trolleit” in honor of the Swedish chemist Hans Gabriel Trolle-Wachmeister (1782–1871).

classification

In the old systematics of minerals according to Strunz (8th edition) the Trolleit belongs to the division of "anhydrous phosphates with foreign anions " and there, together with Barbosalite , Hentschelite , Lipscombit , Scorzalite , Richellite and Wilhelmkleinite, to the lazulite series . Since the new systematics of minerals according to Strunz (9th edition) , this department has been more precisely subdivided according to the size of the cations and the mineral is now the only one in its group in the subdivision of “anhydrous phosphates with foreign anions and exclusively medium-sized cations; (OH, etc.): RO 4 "less than or equal" to find 1: 1 “.

The systematics of minerals according to Dana also assigns the Trolleit to the division of "anhydrous phosphates", but there in the sub-division "with hydroxyl (groups) or halogen (s) with different formulas".

Education and Locations

Trolleite forms in metamorphic rocks such as amphibolite .

So far, the mineral in these localities has been disrupted : In Bundaberg (Queensland) in Australia; in Yamaguchi Prefecture on Honshu in Japan; in the Itremo massif of the Fianarantsoa province in Madagascar; in the East Siberian Region (Transbaikalia) of Russia; in the Western Province of Rwanda ; in the Swedish provinces of Scania , Värmland and Västergötland ; and in California (White Mountains), Colorado (Glendevey) and Virginia (Sprouses Corner) in the USA.

Crystal structure

Trolleit crystallizes in the monoclinic crystal system in the space group I 2 / c with the lattice parameters a  = 18.894  Å , b  = 7.161 Å, c  = 7.162 Å and β = 99.99 °, as well as four formula units per unit cell .

See also

Individual evidence

  1. ↑ a b c Webmineral - Trolleite (engl.)
  2. ↑ a b American Mineralogist Crystal Structure Database - Trolleite (Eng., 1974)
  3. ↑ a b c Trolleite at mindat.org (engl.)
  4. ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .
  5. ↑ Mindat - Localities for Trolleite
  6. ↑ American Mineralogist Crystal Structure Database - Trolleite (Eng., 1974)

Web links

Commons : Trolleite  - collection of images, videos and audio files