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Silicate

Ferro-ferri-nybøite

NaNa₂(Fe²⁺₃Fe³⁺₂)(Si₇Al)O₂₂(OH)₂
Hardness6
Crystal systemMonoclinic
ClassSilicate
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Ferro-ferri-nybøite

Ferro-ferri-nybøite is an IMA-recognized mineral species in the silicate class, with the chemical formula NaNa₂(Fe²⁺₃Fe³⁺₂)(Si₇Al)O₂₂(OH)₂.

It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Amphibole structural group.

Key properties: Mohs hardness 6; specific gravity 3.424; Grayish green to black streak; Vitreous luster; optically biaxial.

IMA symbol Ffnyb, IMA status: approved, named in 2013.

The earliest mineral in an igneous microbreccia in an alkaline syenite-gabbro complex.

It is found associated with An astrophyllite-group mineral, a eudialyte-group mineral, albite, nepheline.

Signifies an amphibole in the compositional range of nybøite with a dominance of Fe2+ and Fe3+ substituting for Mg and Al respectively.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more F minerals or help write this entry.