Amazonite
Amazonite | |
---|---|
General and classification | |
chemical formula | K [AlSi 3 O 8 ] |
Mineral class (and possibly department) |
Framework silicates (tectosilicates) |
System no. to Strunz and to Dana |
see microcline see microcline |
Similar minerals | Turquoise , jade |
Crystallographic Data | |
Crystal system | triclinic |
Crystal class ; symbol | triclinic-pinacoidal 1 |
Twinning | lamellar according to albite law and periclinic law |
Physical Properties | |
Mohs hardness | 6 to 6.5 |
Density (g / cm 3 ) | 2.56 to 2.58 |
Cleavage | good to perfect |
Break ; Tenacity | uneven to scalloped |
colour | green, bluish green |
Line color | White |
transparency | translucent |
shine | Glass gloss, pearlescent |
Crystal optics | |
Refractive index | n = 1.522 to 1.530 |
Birefringence | δ = 0.008 |
Optical character | biaxial negative |
Pleochroism | is missing |
Other properties | |
Chemical behavior | soluble in hydrofluoric acid |
Amazonite , also called Amazon stone , is a light to dark green mineral variety of Mikroklin from the mineral class of silicates , more precisely a framework silicate from the group of feldspars . It crystallizes in the triclinic crystal system and its chemical formula corresponds to that of the microcline (K [AlSi 3 O 8 ]) with a small amount of lead , which is also responsible for the color. Together with the feldspars, the amazonite is one of the most abundant minerals on earth.
Amazonite is only processed into gemstones . One exception is the Amazonite granite called "Monsun", which occurs in Chittor in India and is used in exclusive interior fittings.
Etymology and history
Amazonite was already used to make jewelry in ancient Egypt . Scientists later derived the name from the Amazon River , where it has not yet been found.
In contrast, Alexander von Humboldt (1769-1859) reported on an Indian tribe who lived on the Rio Negro and wore amulets made of amazonite. These should supposedly come from a country where women lived without men ( Amazons ).
Varieties
Since microcline forms a mixed series together with orthoclase , sanidine and albite as the end member, it has now been switched to assigning amazonite to all blue to green, lead-containing varieties of the minerals in question. Amazonite must therefore be viewed as a collective name for the varieties microcline amazonite , orthoclase amazonite , albite amazonite and the various plagioclase amazonites .
Education and Locations
Amazonite forms magmatic in granite , syenite and pegmatite .
Find places are for example in Crystal Peak, Colorado in the USA , Brazil , India , Madagascar and Norway .
Use as a gem stone
For pieces of jewelery, amazonite is usually given the so-called table cut or cabochon cut, but it is also used in spherical form to make necklaces and craft items (e.g. sculptures ). Because of its structure-related good cleavage properties , however, it is very pressure-sensitive and difficult to enclose.
See also
literature
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 264 ( Dörfler Natur ).
- Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags-GmbH., Munich et al. 2002, ISBN 3-405-16332-3 , p. 180 .
Web links
- Mineral Atlas: Amazonite (Wiki)
- MinDat - Amazonite (English) and Mikrocline
- Geology info - the most important minerals
- Gem etiquette - amazonite
Individual evidence
- ↑ What is the most common mineral on earth? Retrieved April 25, 2017 .