Okenite
| Okenite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Ca 10 [Si 6 O 16 | (Si 6 O 15 ) 2 ] · 18 H 2 O |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.EA.40 ( 8th edition : VIII / G.01) 72.03.02.05 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Room group (no.) | P 1 (No. 2) |
| Lattice parameters |
a = 9.69 Å ; b = 7.28 Å; c = 22.02 Å, α = 92.7 °; β = 100.1 °; γ = 110.9 ° |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 4.5 to 5 |
| Density (g / cm 3 ) | measured: 2.28 to 2.33; calculated: 2.33 |
| Cleavage | completely after {001} |
| Break ; Tenacity | uneven to scalloped |
| colour | white to slightly yellowish; colorless in thin layers |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss to pearlescent |
| Crystal optics | |
| Refractive indices |
n α = 1.512 to 1.532 n β = 1.514 to 1.535 n γ = 1.515 to 1.542 |
| Birefringence | δ = 0.003 to 0.010 |
| Optical character | biaxial negative |
| Axis angle | 2V = 60 ° (measured); 68 to 70 ° (calculated) |
| Pleochroism | is missing |
Okenite is a rarely occurring mineral from the mineral class of silicates and germanates . It crystallizes in the triclinic crystal system with the chemical composition Ca 10 [Si 6 O 16 | (Si 6 O 15 ) 2 ] · 18 H 2 O, is thus a water-containing calcium - layered silicate .
Okenite mainly develops leaf- to needle-shaped crystals in radial, spherical mineral aggregates of white to yellowish color.
Special properties
In front of the soldering tube , Okenite puffs up and melts into white glass.
Etymology and history
Okenite was discovered along with many other minerals by Major Petersen, who collected the samples from "Kudlisat am Waygat" on Disko Island ( Kalaallisut : Qeqertarsuaq ) in Greenland and handed them over to the academic collection in Munich, where the Okenite was initially kept as a variety of fiber zeolite has been. However, through a more detailed analysis of the material, Franz von Kobell determined in 1828 that it had to be an independent type of mineral and described it in his lecture on the mineral at the Assembly of German Naturalists in Berlin in September 1828 in honor of the naturalist and founder of the German Assembly Natural scientist and doctors Lorenz Oken as Okenit.
In the archive records published by Karl Wilhelm Gottlob Kastner shortly after the meeting, however, the mineral name ockenite is initially found . This is only corrected in the addendum to Okenit, as it turns out to be a spelling mistake in Kobell's handwritten notes, which was accidentally printed without correction.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the okenite belonged to the mineral class of "silicates and germanates" and there to the department of "transition structures between chain and layered silicates", where it was named after the last update (2008) the only member is the unnamed group VIII / G.01 .
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 okenite to the class of "silicates and germanates", but there directly into the department of "phyllosilicates" . This department is further subdivided according to the crystal structure, so that the mineral can be found according to its composition in the subdivision of the "Simple tetrahedral networks with 4, 5, (6) and 8 participating rings", where it is the only member of the unnamed group 9 .EA.40 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the okenite to the class of "silicates and Germanates", but there in the more finely subdivided division of "layered silicates: two-dimensional unlimited layers with rings other than six-membered". Here it is together with tobermorite , Klinotobermorit , Plombierit , Riversideite , Tacharanit , Dalyite and Oyelith in the "tobermorite (5- and 8-membered rings)" with the system number. 72.03.02 within the subsection of " Layered Silicates: Two-dimensional unlimited layers with rings other than six-membered: 3-, 4-, or 5-membered rings and 8-membered rings ".
Education and Locations
.jpg)
Okenite is formed from hydrothermal solutions in basalt cavities. Accompanying minerals include various zeolites and apophyllites as well as calcite , prehnite and quartz (e.g. as chalcedony ).
As a rare mineral formation, Okenite has so far (as of 2012) only been found at a few sites, with around 60 sites being known. In Greenland, Okenit has so far only appeared at its type locality Disko Island.
The area around Poona in India is especially known for its rich okenite finds in the form of spherical aggregates in basalt cavities .
In Germany, Okenit was found at the Teichelberg and the Zeilberg quarry in Bavaria and at the Bramburg quarry in Lower Saxony. The only known site in Austria so far is on the Bruck expressway , near the Kirchdorf tunnel in the Styrian community of Pernegg an der Mur .
Other locations are in the Antarctic, Australia, Azerbaijan, Chile, Costa Rica, Denmark, Iceland, Israel, Italy, Canada, Mexico, New Zealand, Norway, Romania, Russia, Ukraine, Hungary, in the United Kingdom (Great Britain) and the United States of America.
Crystal structure
Okenite crystallizes triclinic in the space group P 1 (space group no. 2) with the lattice parameters a = 9.69 Å ; b = 7.28 Å; c = 22.02 Å; α = 92.7 °; β = 100.1 ° and γ = 110.9 ° and one formula unit per unit cell .
See also
Web links
Individual evidence
- ↑ 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. 661 .
- ↑ Webmineral - Okenite
- ^ A b John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Okenite. In: Handbook of Mineralogy, Mineralogical Society of America. 2001 ( PDF 72.3 kB )
- ↑ a b c d e Mindat - Okenite
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 (first edition: 1891).
- ↑ Archive for the entire study of nature, Volume 14 (pp. 333–337) in the Google book search
- ↑ Archive for the entire study of nature, Volume 14 (p. 493) in the Google book search
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th, completely reworked and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
- ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (= Dörfler Natur ). Nebel Verlag, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 243 .