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
CategoryPhosphate mineral
Formula
(repeating unit)
Fe2+
Fe3+
2
(PO
4
)
2
(OH)
2
·6H
2
O
IMA symbolMviv[1]
Strunz classification8.DC.25 (10 ed)
7/C.14-20 (8 ed)
Dana classification40.11.9.4
Crystal systemTriclinic
Crystal classPinacoidal (1)
Space groupP1bar
Unit cella = 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 mass499.548 g/mol
ColorDark blue to blue-black; Dark green to green-black
Crystal habitBladed crystals, often with irregular acute multiple terminations.
Twinning{110}
CleavagePerfect on {110}
TenacitySectile
Mohs scale hardness1.5-2
LusterSub-vitreous, Resinous, Greasy, Dull
StreakBlue or greenish blue
Diaphaneitytranslucent
Specific gravity2.69
Optical propertiesBiaxial (+)
Refractive indexnα = 1.600 - 3.000, nβ = 1.640 - 3.000, nγ = 1.685 - 3.000[2]
Birefringenceδ = 0.050 - 0.085
PleochroismVisible; X = blue to blue-green; Y,Z = yellow-green
2V angleMeasured: 85° (5), Calculated: 90°
DispersionVery weak
Ultraviolet fluorescenceNot fluorescent
References[2][3][4]

Metavivianite (Fe2+
Fe3+
2
(PO
4
)
2
(OH)
2
·6H
2
O
) is a hydrated iron phosphate mineral found in a number of geological environments. As a secondary mineral it is typically formed from oxidizing vivianite.[2] Metavivianite is typically found as dark blue or dark green prismatic to flattened crystals.

It was named by C. Ritz, Eric J. Essene, and Donald R. Peacor in 1974 for its structural relationship to vivianite.[3]

See also

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. 1 2 3 John W. Anthony; Richard A. Bideaux; Kenneth W. Bladh & Monte C. Nichols (2005). "Handbook of Mineralogy" (PDF). Mineral Data Publishing. {{cite journal}}: Cite journal requires |journal= (help)
  3. 1 2 Metavivianite (Mindat.org)
  4. Metavivianite Webmineral Data


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