May 16 2013
Sherwoodite has aluminovanadate (IV,V) polyanions, with 14 (VO6) octahedra condensed by edge-sharing around a central (AlO6) octahedron
Chemical Formula – Ca9(AlV4+2 V5+12 O40)2 •56H2O - (the exponent and subscript are on the same line pls see original
Properties of Sherwoodite
The following are the key properties of Sherwoodite
- Cell Data
- Space Group: I4/amd
- a = 28.06
- c = 13.56
- Z = 4
- Crystal Data
- Tetragonal
- Point Group: 4/m 2/m 2/m
- As euhedal crystals, equant or flattened to 1 mm
- X-ray powder pattern: 12.3 (s), 10.0 (s), 9.3 (ms), 2.61 (m), 2.10 (mb), 7.8 (w), 7.1 (w)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| V2O5 |
52.1 |
52.85 |
| V2O4 |
6.2 |
8.03 |
| Al2O3 |
2.7 |
2.47 |
| Fe2O3 |
0.8 |
|
| MgO |
0.5 |
|
| CaO |
13.7 |
12.33 |
| H2O |
24.0 |
24.43 |
| Total |
[100] |
[100] |
- Optical Properties
- Optical Class: Uniaxial (-)
- Σ = 1.735 – 1.738 - Sigma
- Estimated Properties
| Electron density |
Bulk density (electron density)= 2.55 g/cm3
note: Specific gravity of sherwoodite = 2.57 g/cm3 |
| Photoelectric |
PESherwoodite = 7.60 barns/electron
U=PESherwoodite x ρElectron Density= 19.39 barns/cc. |
| Fermion index |
Fermion Index = 0.0012383612
Boson Index = 0.9987616388 |
| Radioactivity |
Sherwoodite is not radioactive |
How to Identify Sherwoodite
Sherwoodite is a semi-transparent, dark blue-black with progressive alteration turning yellow-green or blue-green and has a vitreous to earthy luster.
Global Distribution
Sherwoodite is distributed in the following places:
- In the USA, in Colorado, from the Peanut and Jo Dandy mines,
- Bull Canyon district, Uravan district, Montrose Co., at the Fall Creek mine, Placerville, San Miguel Co., and the Matchless mine, Calamity Mesa, Mesa Co.; on Wilson Mesa, Grand Co., Utah;
- in the Shadyside mine, east Carrizo Mountains, San Juan Co., New Mexico; and in the Joleo mine, Apache Co., Arizona
- From Minasragra, 46 km from Cerro de Pasco, Peru.
Occurrence of Sherwoodite and Useful Mineral Association
Sherwoodite is an oxidation product of lower valent vanadium minerals, on fracture surfaces and replacing fossil wood in Colorado Plateau-type U–V deposits and is mostly widely distributed. Mineral associations include selenium, metatyuyamunite, melanovanadite in the Colorado Plateau, USA) and pascoite, pyrite, copper, gypsum, patronite, melanovanadite in Minasragra, Peru.
References