Tremolite
| Tremolite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Ca 2 Mg 5 [(OH, F) | Si 4 O 11 ] 2 |
|
Mineral class (and possibly department) |
Silicates and germanates - chain silicates and band silicates, calcium amphibole group |
|
System no. to Strunz and to Dana |
9.DE.10 ( 8th edition : VIII / F.10) 66.01.03a.01 |
| Similar minerals | Wollastonite |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic 2 / m |
| Room group (no.) | C 2 / m (No. 12) |
| Lattice parameters |
a = 9.86 Å ; b = 18.05 Å; c = 5.29 Å β = 104.8 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 5 to 6 |
| Density (g / cm 3 ) | measured: 2.99 to 3.03; calculated: 2.964 |
| Cleavage | completely after {110}; Transverse secretions below 56 ° and 124 ° |
| Break ; Tenacity | uneven to scalloped, brittle |
| colour | white, gray, brown, green, purple to pink |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss, silk gloss, matt |
| Crystal optics | |
| Refractive indices |
n α = 1.599 to 1.612 n β = 1.613 to 1.626 n γ = 1.625 to 1.637 |
| Birefringence | δ = 0.026 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 88 to 80 °; calculated: 82 to 84 ° |
| Pleochroism | colorless |
| Other properties | |
| Special features | fluorescence |
The mineral tremolite (also grammatite ) is a frequently occurring chain silicate from the group of calcium amphiboles . It crystallizes in the monoclinic crystal system with the chemical composition Ca 2 Mg 5 [(OH, F) | Si 4 O 11 ] 2 and develops mostly columnar, needle-like and radial crystals , but also fibrous, granular and columnar mineral aggregates in the colors white (with 100% magnesium), gray, brown, green (small amount of iron) and pink. As the iron content rises, the color becomes darker. Its hardness is between 5 and 6 and its density between 2.9 and 3.2.
Tremolite is the end member of the Tremolit- actinolite - Ferro-actinolite - mixed batch with variable exchangeable magnesium - ions (tremolite) and iron ions (ferro-actinolite).
Etymology and history
Was first discovered tremolite in Campolungo in Val Piumogna in the Swiss Ticino and described in 1790 by Johann Georg Albrecht Hoepfner , of the mineral after the Gotthard Pass lying Val Tremola named, which he mistakenly referred to as type locality had documented. Later (Hey's Mineral Index (1993)) the mineral was also found in Val Tremola.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the tremolite belonged to the mineral class of "silicates and germanates" and there to the department of "chain silicates and band silicates (inosilicates)", where together with actinolite , alumino-ferrotschermakite , Cannilloit , chloro-Kaliumhastingsit , Edenit , ferric Ferrotschermakit , Ferrisadanagait , Ferritschermakit , ferro-actinolite , ferro-alumino-Tschermakit , Ferro-Edenit , ferro-hornblende , Ferro-Kaersutite , Ferro-Pargasit , Ferrotschermakit , Fluorocannilloit , fluoro Edenit , Hastingsite , Kaersutite , potassium Chloropargasit , potassium Ferrisadanagait , potassium Magnesiosadanagait , Kaliumpargasit , Kaliumsadanagait , Magnesiohastingsit , magnesio-hornblende , Magnesiosadanagait , Pargasit , Sadanagait and Tschermakit an independent amphibole subgroup is the "calcium amphiboles".
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 the tremolite to the class of "silicates and germanates" and there in the department of "chain and band silicates (inosilicates)" a. However, this division is further subdivided according to the type of chain formation and according to whether it belongs to larger mineral families, so that the mineral is classified according to its composition in the subdivision of “chain and ribbon silicates with 2-periodic double chains, Si 4 O 11 ; Amphibole family, Klinoamphibole "is to find where it along with actinolite, alumino-Ferrotschermakit , Aluminotschermakit, Cannilloit, ferric Ferrotschermakit, Ferritschermakit, ferro-actinolite, ferro-hornblende, Ferrotschermakit, Fluorocannilloit, Fluorotremolit , Joesmithit , Magnesio-hornblende, Parvo-Manganotremolit and Tschermakit the "tremolite group of Ca-Klinoamphibole" named after him with the system no. 9.DE.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the tremolite to the class of "silicates and germanates", but there in the more finely divided division of "chain silicates: double unbranched chains, W = 2". Here it is together with actinolite, ferro-actinolite, magnesio-hornblende, ferro-hornblende, chermakite, aluminoferrotschermakite, ferri-ferrotschermakite, ferrotschermakite, ferro-aluminochermakite, ferrite schermakite, ferroferritschermakite, ferro-edenite, fluoro-edenite, pargasmakite , Ferropargasit, Ferrochloropargasit, potassium Chloropargasit, potassium Ferropargasit, Magnesiohastingsit, Hastingsite, potassium Chlorohastingsit, fluoro-Magnesiohastingsit, potassium Magnesiohastingsit, chloro-Kaliumhastingsit, fluoro-Kaliumhastingsit, potassium Magnesiosadanagait, Sadanagait, Kaliumsadanagait, Kaliumferrisadanagait, Magnesiosadanagait, Kaersutite , Ferrokaersutit, Fluorocannilloit and Cannilloit in the "Group 2, Calcium-Amphibole" with the system no. 66.01.03a to be found within the subsection of " Chain Silicates: Double unbranched chains, W = 2 amphibole configuration ".
Crystal structure
Tremolite crystallizes monoclinically in the space group (space group no. 12) with the lattice parameters a = 9.86 Å ; b = 18.05 Å; c = 5.29 Å and β = 104.8 ° and 2 formula units per unit cell .
properties
Depending on where they were found, some tremolites show a bluish, but also green, orange, pink to red or white fluorescence under short - wave UV light and an orange or pink to red fluorescence under long-wave UV light .
Modifications and varieties
One variety is the so-called mountain leather , which consists of mineral fibers that are matted together and looks very similar to leather .
Hexagonite is a violet variety of tremolite due to a small amount of manganese .
With actinolite , tremolite forms a complete series of mixtures. The corresponding mixed crystals , which are very hard, are called nephrite and, because of their characteristic greenish color, also called jade (in addition to the predominantly jadeite rock).
Purple hexagonite from the Balmat-Edwards zinc mining area, St. Lawrence County, New York, USA (size: 38.1 × 38.1 mm)
Green tremolite from the Ibity massif, Madagascar (size: 2.2 × 1.2 × 0.6 cm)
-300273.jpg)
Education and Locations
Tremolite forms metamorphically and occurs in talc schist and often in impure crystalline varieties of dolomitic limestone . It occurs less frequently in pyroxe deposits of igneous rocks . Begleitminerale include calcite , Cummingtonite , diopside , dolomite , forsterite , calcium-containing shell , talc , Magnesio-Cummingtonite , Riebeckite , winchite and wollastonite .
In total, tremolite has so far (as of 2011) been detected at around 1,600 sites. In addition to its type locality Campolungo in Val Piumogna and the Val Tremola on the Gotthard Pass, the mineral was also found in Switzerland at Fusio in the Ticino district of Vallemaggia, on the Ofenhorn and on the Geisspfad in the Binn valley and at Martigny in the canton of Valais.
In Germany, tremolite has been found on Silberberg near Todtnau in Baden-Württemberg, in several places in Franconia and Lower Bavaria , near Roßbach ( Bensheim ) in the Hessian Odenwald, near Bad Harzburg in Lower Saxony, near Breitenbrunn / Erzgeb. , Schneeberg and Beierfeld in the Ore Mountains and near Oelsnitz in Vogtland in Saxony and near Barmstedt and Schönberg in Schleswig-Holstein.
In Austria the mineral could be found in several places in Burgenland , in Carinthia , Lower Austria , Salzburg , Styria as well as in the Tyrolean Inn and Zillertal .
Other locations are Afghanistan , Egypt , Antarctica , Argentina , Ethiopia , Australia , Bangladesh , Bolivia , Brazil , Bulgaria , Chile , China , Fiji , Finland , France , Georgia , Greece , Greenland , Haiti , India , Iran , Ireland , Italy , Japan , Canada , Kazakhstan , Kenya , North and South Korea , Madagascar , Malaysia , Morocco , Mexico , Myanmar , Namibia , New Zealand , Norway , Pakistan , Peru , Poland , Portugal , Romania , Russia , Zambia , Zimbabwe , Slovakia , Spain , Sweden , South Africa , Taiwan , Tanzania , the Czech Republic , Turkey , Ukraine , Hungary , the US Virgin Island of Saint John , the United Kingdom (Great Britain) and the United States of America (USA).
Tremolite could also be found in rock samples from the Mid-Atlantic Ridge .
use
Fibrous tremolites were used to make asbestos .
For geologists and petrologists , tremolite is a temperature indicator because it turns into diopside at higher temperatures .
See also
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. 627 .
- ↑ a b c Handbook of Mineralogy - Tremolite (English, PDF 78.8 kB)
- ↑ a b c d Tremolite at mindat.org (engl.)
- ↑ Philippe Roth: The Early History of Tremolite (English, PDF 477.3 kB; MineralogicalRecord.com 2006)
- ↑ a b Mindat - Localities for Tremolite
- ↑ a b Mineralienatlas: fluorescence / table
literature
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 726 .
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 239 .
