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.

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]

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

See also

edit

References

edit
  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. ^ a b c 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. ^ a b Metavivianite (Mindat.org)
  4. ^ Metavivianite Webmineral Data