Andesine
| Andesine | ||
|---|---|---|
2V angle Measured: 76° to 83° | | |
| Diagnostic features | Requires optical/chemical analysis | |
| References | [1][2][3][4] | |
Andesine is a silicate mineral, a member of the plagioclase feldspar solid solution series. Its chemical formula is (Ca, Na)(Al, Si)4O8, where Ca/(Ca + Na) (% anorthite) is between 30 and 50%. The formula may be written as Na0.7-0.5Ca0.3-0.5Al1.3-1.5Si2.7-2.5O8.[2]
The plagioclase feldspars are a continuous solid solution series and as such the accurate identification of individual members requires detailed
It is sometimes used as a gemstone.[6]
Name and discovery
Andesine was first described in 1841 for an occurrence in the Marmato mine, Marmato, Cauca, Chocó Department, Colombia.[3][4] The name is for the Andes due to its abundance in the andesite lavas in those mountains.[2][5]
In the early 2000s, red and green gemstones began to be marketed under the name of 'andesine'. After some controversy, these gemstones were subsequently discovered to have been artificially-colored.[7]
Occurrence
Andesine occurs in
References
- ^ Mineralienatlas
- ^ a b c d Handbook of Mineralogy
- ^ a b Webmineral data
- ^ a b Mindat.org
- ^ ISBN 0-471-80580-7
- ^ Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens p.118
- ^ "Three Occurrences of Oregon Sunstone | Gems & Gemology".
External links
