May 9 2013
Nontronite is named after the place at which it was discovered, near Saint-Pardoux, Nontron, France. It was discovered in the year 1827.
Properties of Nontronite
The key physical properties of Nontronite are as below:
- Cell Data
- Space group: C2/m
- a = 5.23 – 5.26
- c=14.8 – 15.8
- Z = n.d
- Crystal Data
- Monoclinic
- Point group: 2/m
- Crystals – rarely as small bladed crystals, radial or reticulated, spherulitic, commonly cryptocrystalline, claylike massive.
- X-ray powder pattern: Nontron, France
15.4 (vs), 4.56 (vs), 2.64 (vs), 2.56 (vs), 1.52 (vs), 2.43 (s), 1.72 (s)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| SiO2 |
48.82 |
40.25 |
| TiO2 |
- |
0.03 |
| Al2O3 |
4.30 |
5.50 |
| Fe2O3 |
35.88 |
29.44 |
| MgO |
0.35 |
0.53 |
| CaO |
- |
2.29 |
| H2O+ |
- |
7.25 |
| H2O- |
- |
15.09 |
| H2O |
9.66 |
- |
- Optical Properties
- Translucent to opaque
- Optical class- Biaxial
- Lustre – Waxy, resinous, dull
- Estimated Properties
| Electron density |
Bulk density (electron density)= 2.28 g/cm3
note: Specific gravity of Nontronite = 2.28 g/cm3 |
| Photoelectric |
PENontronite = 7.45 barns/electron
U=PENontronite x ρelectron density= 17.00 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Nontronite is not radioactive |
How to Identify Nontronite
Nontronite appears as a dull, resinous and waxy mineral. The color varies from greenish yellow, olive green and brownish green. This mineral has a hardness of 1.5 – 2, between talc to gypsum. It is non-fluorescent.
Global Distribution
Nontronite is found in the following locations:
- France – from Saint-Pardoux, Froland, Norway
- Sweden – from Vittensten
- Russia- from Okhansk
- Germany – from Saxony, Geilsdorf and Wolkenstein
- Madagascar – from Faratsiho
- Australia – from Burra copper mine, Tamworth copper mine, Attunga, New South Wales
- USA – Spruce Pine District, North Carolina, Washington, Crestmore, Riverside, Woody Kern, California.
Occurrence of Nontronite and Useful Mineral Association
Nontronite occurs as a weathering product of basalts, kimberlites and other ultramafic igneous rocks; in poorly-drained volcanic ash soils, in some hydrothermally altered mineral deposits, midocean ridge basalts and contact metamorphosed limestones. It is usually associated with minerals such as quartz, opal, hornblende, mica, kaolinite, olivine and pyroxenes.
References