Jun 3 2014
Andesine, a member of the plagioclase feldspar solid solution group, was first discovered in 1841 for an occurrence in the Marmato mine, Colombia, Chocó Department and Cauca.
Properties of Andesine
The following are the key properties of Andesine:
- Cell Data
- Space Group: P1
- a = 8.151(3)
- b = 12.829(5)
- c = 14.206(7)
- α = 93:62(3) °
- β = 116:21(2) °
- = 89:70(2) °
- Z = 8
- Crystal Data
- Triclinic
- Point group: 1
- Crystals rare, to 2cm
- Commonly massive, cleavable, or granular
- Twinning: Commonly twinned after Albite, Pericline, and Carlsbad laws
- Also twinned after a law similar to the Manebach law
- X-ray powder pattern: 3.21 (100), 3.18 (90), 4.04 (80), 3.76 (70), 3.65 (70), 3.14 (70), 2.93 (70b)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
Content 3 |
| SiO2 |
57.59 |
60.76 |
55.59 |
| Al2O3 |
25.84 |
24.82 |
24.82 28.30 |
| CaO |
8.45 |
6.30 |
10.38 |
| Na2O |
6.39 |
8.12 |
5.73 |
| Fe2O3 |
0.92 |
- |
- |
| K2O |
0.55 |
- |
- |
| H2O+ |
0.32 |
- |
- |
| H2O- |
0.05 |
- |
- |
| MgO |
trace |
- |
- |
| Total |
100.11 |
100.00 |
100.00 |
- Optical Properties
- Optical Class: Biaxial (+)
- Dispersion: r > v; weak
- α = 1.545-1.556
- β = 1.548-1.558
- γ = 1.552-1.563
- 2V(meas.) = 78°-90° (low); 73° -80° (high)
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.65 g/cm3
note: specific gravity of andesine = 2.67 g/cm3 |
| Photoelectric |
PEAndesine = 2.27 barns/electron
U = PEAndesine x ρElectron Density = 6.01 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
Andesine is not radioactive
|
How to Identify Andesine
Andesine can be identified in the field by its white, gray, and yellow transparent, sub-transparent, or translucent appearance. It has a glassy lustre with a white streak. This mineral has a hardness of 7 – similar to Quartz - and a non-fluorescent luminescence.
Andesine can also be identified by its density that ranges from 2.66 to 2.68.
Global Distribution
Adesine is widely distributed in many locations. The key locations are listed below:
- France - St. Raphael, Esteerel Mountains, Var, and near Chagey, Haute-Saone
- Germany - Bodenmais, Bavaria
- Italy - Mt. Arcuentu, Sardinia
- Iceland - Vapnefjord
- Normay - Sannidal and Arendal
- Japan - Kaneda, Miyagi Prefecture; Naka, Iwojima Island and Kuzuhara, Toyama Prefecture
- Korea - Minsen
- Australia - Cape Grant, Victoria
- USA - Sanford, York Co. Maine
- Andesite lavas of the Andes Mountains
Occurrence of Andesine and Useful Mineral Association
Andesine occurs as andesites and syenites in igneous rocks of intermediate silica content.
It has useful mineral associations with biotite, magnetite, quartz, hornblende, and K feldspar.
References
http://rruff.geo.arizona.edu/doclib/hom/andesine.pdf
http://webmineral.com/data/Andesine.shtml
http://www.mindat.org/min-220.html