Ammoniomagnesiovoltaite
Ammoniomagnesiovoltaite is an IMA-recognized mineral species in the sulfate class, with the chemical formula (NH₄)₂Mg₅Fe³⁺₃Al(SO₄)₁₂·18H₂O.
It crystallizes in the cubic crystal system (space group Fd3c). It is a member of the Voltaite structural group.
Key properties: Mohs hardness 2–3; specific gravity 2.55; White streak; Vitreous luster.
IMA symbol Amvlt, IMA status: approved, named in 2009.
Occurs as efflorescences formed by chemical reactions as ground water interacts with organic matter from coal and oxidizing pyrite and marcasite on a burning coal dump.
It is found associated with Tschermigite, sabieite, kieserite, pickeringite, hexahydrite.
As an analog of voltaite with essential ammonium and magnesium in the composition.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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