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Formula: K2Na6Fe2+Fe3+6O2(SO4)12.18H2O
Hydrated sulphate
Crystal System: Trigonal
Specific gravity: 2.51 measured, 2.435 calculated
Hardness: 2½
Streak: Brownish yellow
Colour: Yellowish brown, orange-brown, greenish brown
Solubility: Partially soluble in water, decomposed by dilute acids
Environments
Hydrothermal environments
Sublimates
Metavoltine occurs typically as an alteration product of pyrite in arid
climates, also formed as a fumarolic sublimate and solfataric precipitate, and may be a post-mining product. Associated
minerals include voltaite, botryogen,
ferrinatrite, coquimbite,
copiapite, sideronatrite,
metasideronatrite, jarosite,
alunogen, pickeringite,
sulphur and gypsum
(HOM).
Localities
At La Compañia Mine, Sierra Gorda, Antofagasta Province, Antofagasta, Chile, metavoltine has been found with
ferrinatrite
(Mindat photo).
Metavoltine from La Compañia Mine - Image
At the Chuquicamata Mine, Chuquicamata District, Calama, El Loa Province, Antofagasta, Chile, metavoltine occurs
with copiapite, alunogen and other
sulphates
(Dana).
Metavoltine from the Chuquicamata Mine -
Image
At the type locality, the Zagh Mine, Haji Abad, Bandar Abbas, Bandar Abbas County, Hormozgan Province, Iran,
metavoltine occurs as an alteration of pyritic
trachyte
(Dana).
Metavoltine from the Zagh Mine - Image
At the Huron Shale burn site, Huron River, Huron county, Ohio, USA, metavoltine occurs as very small brown
rosettes of hexagonal crystals in association with alunogen and
clairite, on surfaces of shale
clasts in close association with salammoniac and
sulphur
(R&M 92-3.256).
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