Andesine
| Andesine | |
|---|---|
 |
|
| General and classification | |
| chemical formula | (Na, Ca) Al (Si, Al) 3 O 8 |
|
Mineral class (and possibly department) |
Framework silicates , feldspar group |
|
System no. to Strunz and to Dana |
9.FA.35 ( 8th edition : VIII / J.07) 76.01.03.03 |
| Crystallographic Data | |
| Crystal system | Triclinic |
| Crystal class ; symbol | triclinic-pinacoidal 1 |
| Physical Properties | |
| Mohs hardness | 6 to 6.5 |
| Density (g / cm 3 ) | 2.7 |
| Cleavage | Well |
| Break ; Tenacity | uneven to scalloped |
| colour | gray, yellow, red, light green |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.543 to 1.554 n β = 1.547 to 1.559 n γ = 1.552 to 1.562 |
| Birefringence | δ = 0.009 |
| Optical character | alternating biaxially |
| Axis angle | 2V = 76 ° to 83 ° (measured), 78 ° to 84 ° (calculated) |
Like labradorite, andesine is no longer considered an independent mineral today , but is a plagioclase , a mineral mixture of albite and anorthite from the group of feldspars within the mineral class of silicates with the general empirical formula (Na, Ca) Al (Si, Al) 3 O 8 . Structurally, andesine belongs to the tectosilicates .
Andesine crystallizes in the triclinic crystal system and is mainly found in the form of granular to massive, but also flat mineral aggregates .
Etymology and history
Andesin was named after its first place of discovery, the South American Andes .
Chemism
Andesine, together with albite , oligoclase , labradorite , bytownite and anorthite, forms the perfect mixed series of plagioclase. Plagioclase with a content of 30 to 50 mol% anorthite (An 30 to An 50 ) are called andesine.
Varieties
- Belomorite - pink-white color, iridescent bluish .
Education and Locations
Andesine is one of the rock-forming minerals and forms magmatic in andesites , granodiorites and diorites . It also occurs metamorphically in gneisses and migmatites .
Locations include Bodenmais in Germany , the Esterel Mountains and the Massif Central in France , Adamello in Italy and the Andes in South America .
See also
literature
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 600 .
- Helmut Schrätze , Karl-Ludwig Weiner : Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 881 .
Web links
- Mineral Atlas: Andesine and Belomorite (Wiki)
- Webmineral - Andesine (Engl.)
- Mindat - Andesine (Engl.)