Glaucophane
| Glaucophane | |
|---|---|
 ( total size of the step : 11.4 × 6.9 × 3.8 cm) |
|
| General and classification | |
| chemical formula | □ Na 2 (Mg, Fe) 3 Al 2 [(OH) 2 | Si 8 O 22 ] |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.DE.25 ( 8th edition : VIII / F.08) 66.01.03c.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | C 2 / m (No. 12) |
| Lattice parameters |
a = 9.53 Å ; b = 17.74 Å; c = 5.30 Å β = 103.7 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 6th |
| Density (g / cm 3 ) | measured: 3.08 to 3.22; calculated: 3.132 |
| Cleavage | completely after {110} |
| colour | blue-black to lavender blue |
| Line color | blue-gray |
| transparency | translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.606 to 1.637 n β = 1.615 to 1.650 n γ = 1.627 to 1.655 |
| Birefringence | δ = 0.021 |
| Optical character | biaxial positive |
| Axis angle | 2V = 10 to 80 ° (measured); 62 to 84 ° (calculated) |
| Pleochroism | strong: α = pale yellow; β = violet; γ = deep blue |
Glaucophane is a rather seldom occurring mineral from the mineral class of silicates and germanates . It crystallizes in the monoclinic crystal system with the chemical composition □ Na 2 (Mg, Fe) 3 Al 2 [(OH) 2 | Si 8 O 22 ]. The elements magnesium and iron indicated in round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral. The symbol □ indicates that this structural space is not completely occupied.
Glaucophane is translucent and develops prismatic crystals , but mostly occurs in stem-like, fibrous, granular or massive mineral aggregates . Its color varies between black-blue, gray-blue and lavender blue; it can also have a zonal color change. Glaucophan leaves a blue-gray line on the whiteboard . A glass-like sheen appears on unweathered crystal surfaces .
Special properties
Glaucophane melts very easily in front of the soldering tube , initially turning yellowish-brown and finally dissolving into a dirty olive-green glass. Acids only incompletely decompose the mineral.
Etymology and history
The mineral was named because of its distinctive bluish-gray color after the ancient Greek words Γλαύκος glaukós for sparkling, shiny, luminous, meaning the bright shine of the sky, the sea or the human eye and leaves a certain leeway with regard to the color, and φαίνω phaínō for "appear, appear".
Glaucophane was first found and described in 1845 by Johann Friedrich Ludwig Hausmann . The type locality is the Greek island of Syros .
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Glaukophan belonged to the department of " chain silicates and band silicates (inosilicates)" where he collaborated with Arfvedsonit , Dellaventurait , Eckermannit , Ferrinybøit , ferric Ottoliniit , Ferriwhittackerit , ferrous Eckermannit , Ferroglaukophan , Ferroleakeit , fluoro Ferroleakeit , fluoro-potassium Magnesio-Arfvedsonit , fluoro-magnesio-Arfvedsonit , fluoro Natriumpedrizit , Fluoronybøit , Kaliumarfvedsonit , Kaliumleakeit , Kornit , Kozulith , Leakeit , Magnesio-Arfvedsonit , Magnesioriebeckite , sodium Ferripedrizit , Sodium-Ferri-Ferropedrizit , Nybøit , Obertiit , Riebeckit and Ungarettiit the subgroup of "Alkali-Amphiboles" with the system no. VIII / F.08 within the amphibole group.
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 classifies glaucophane in the category of "chain and band silicates (inosilicates)". However, this department is further subdivided according to the crystal structure and membership of closely related mineral families, so that the mineral as a member of the "Alkali-Klinoamphibole, Glaukophan-Eckermannit-Gruppe" with the system no. 9.DE.25 can be found.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , classifies glaucophane in the category of "chain silicates: double unbranched chains, W = 2". Here it belongs to " Group 4, sodium amphiboles " with system no. 66.01.03c within the subsection "Chain Silicates: Double unbranched chains, W = 2 amphibole configuration".
Modifications and varieties
- Gastaldite is a mixed crystal between glaucophane and actinolite , in which the actinolite component predominates.
- Crossite (1997 discredited by the IMA) is considered as one member of the series Glaukophan and Ferroglaukophan or series Riebeckite or Magnesioriebeckite .
Education and Locations
Glaucophane forms as a typical metamorphic mineral, mainly in slate and gneiss . As Begleitminerale occur among other actinolite , aragonite , Barroisit , chlorite , crossite , Cummingtonite , epidote , jadeite , Lawsonite , omphacite and Pumpellyite on.
As a rather rare mineral formation, glaucophane can sometimes be abundant at various sites, but overall it is not very common. So far (as of 2012) around 230 sites are known to be known. In addition to its type locality Syros, the mineral occurred in Greece on other islands of the Cyclades as well as at Neapoli Vion ( Neapolis ) in Laconia , on Arki in the southern Aegean Sea and Euboea in central Greece.
In Austria the glaucophane could be found in several places in Carinthia (Hohe Tauern, Villach) and Salzburg (Grabenbach). The only previously known site in Germany is Triberg in the Black Forest and in Switzerland the mineral was found in a few places in the municipality of Täsch in the canton of Valais.
Other locations include the Antarctic, Australia, China, Ecuador, France, Guatemala, Italy, Jamaica, Japan, Colombia, Cuba, Madagascar, Macedonia, Myanmar, New Caledonia, Norway, Oman, Portugal, Romania, Russia, Sweden, Slovakia, the Czech Republic, Turkey and the United States of America.
Crystal structure
Glaucophane crystallizes in the monoclinic crystal system in the space group C 2 / m with the lattice parameters a = 9.53 Å , b = 17.74 Å and c = 5.30 Å; β = 103.7 ° and two formula units per unit cell .
See also
literature
- Carl Friedrich Rammelsberg: Glaucophane . In: Second supplement to the concise dictionary of the chemical part of mineralogy . CG Lüderitz, Berlin 1845, p. 55–56 ( limited preview in Google Book Search).
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1979, ISBN 3-342-00288-3 , p. 532 .
- Helmut Schrätze, Karl-Ludwig Weiner: Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 796 .
- Martin Okrusch, Siegfried Matthes: Mineralogy: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin, Heidelberg, New York 2005, ISBN 3-540-23812-3 , pp. 315, 330, 337, 388, 397 ff .
Web links
- Mineral Atlas: Glaucophane (Wiki)
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. 632 .
- ↑ Webmineral - Glaucophane
- ↑ a b c John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Glaucophane , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 78.9 kB )
- ↑ a b c d Mindat - Glaucophane
- ^ A b Paul Ramdohr , Hugo Strunz : Klockmanns textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 730 .
- ^ Carl Friedrich Rammelsberg: Glaukophan . In: Second supplement to the concise dictionary of the chemical part of mineralogy . CG Lüderitz, Berlin 1845, p. 55 ( limited preview in Google Book search).
- ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 227 .
- ↑ Mineral Atlas: Crossit
- ↑ Mindat - Localities for Glaucophane