Metavivianite
Metavivianite (Fe3+
2(PO
4)
2(OH)
2·6H
2O) is a hydrated iron phosphate mineral found in a number of geological environments. As a secondary mineral it is typically formed from oxidizing and dehydrated vivianite.[1] Metavivianite is typically found as dark blue or dark green prismatic to flattened crystals.
| Metavivianite | |
|---|---|
 A 6x4 cm specimen of paramorphosed olive-green to green Metavivianite after oxidized vivianite. From Kerchenskoe deposit, Crimea Oblast, Ukraine. Photo and collection specimen by Pavel Kartashov. | |
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | Fe3+ 2(PO 4) 2(OH) 2·6H 2O |
| Strunz classification | 8.DC.25 (10 ed) 7/C.14-20 (8 ed) |
| Dana classification | 40.11.9.4 |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) |
| Space group | P1 |
| Unit cell | a = 7.989(1) Å, b = 9.321(2) Å c = 4.629(1) Å; α = 97.34(1)°; β = 95.96(1)°; γ = 108.59(2)° |
| Identification | |
| Formula mass | 443.734 g/mol |
| Color | Dark blue to blue-black; Dark green to green-black |
| Crystal habit | Bladed crystals, often with irregular acute multiple terminations. |
| Twinning | {110} |
| Cleavage | Perfect on {110} |
| Tenacity | Sectile |
| Mohs scale hardness | 1.5-2 |
| Luster | Sub-vitreous, Resinous, Greasy, Dull |
| Streak | Blue or greenish blue |
| Diaphaneity | translucent |
| Specific gravity | 2.69 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.600 - 3.000, nβ = 1.640 - 3.000, nγ = 1.685 - 3.000[1] |
| Birefringence | δ = 0.050 - 0.085 |
| Pleochroism | Visible; X = blue to blue-green; Y,Z = yellow-green |
| 2V angle | Measured: 85° (5), Calculated: 90° |
| Dispersion | Very weak |
| Ultraviolet fluorescence | Not fluorescent |
| References | [1][2][3] |
It was named by C. Ritz, Eric J. Essene, and Donald R. Peacor in 1974 for its structural relationship to vivianite.[2]
See also
References
- John W. Anthony; Richard A. Bideaux; Kenneth W. Bladh & Monte C. Nichols (2005). "Handbook of Mineralogy" (PDF). Mineral Data Publishing. Cite journal requires
|journal=(help) - Metavivianite (Mindat.org)
- Metavivianite Webmineral Data
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