Metavoltine

metavoltine

voltaite

copiapite

alunogen

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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 the Chuquicamata Mine, Chuquicamata District, Calama, El Loa Province, Antofagasta, Chile, metavoltine occurs with copiapite, alunogen and other sulphates (Dana).

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).

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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