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Silicate

Potassic-magnesio-arfvedsonite

KNa₂(Mg₄Fe³⁺)Si₈O₂₂(OH)₂
Crystal systemMonoclinic
ClassSilicate
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Potassic-magnesio-arfvedsonite

Potassic-magnesio-arfvedsonite is an IMA-recognized mineral species in the silicate class, with the chemical formula KNa₂(Mg₄Fe³⁺)Si₈O₂₂(OH)₂.

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

Key properties: specific gravity 3.24; Gray-green streak; Vitreous luster; optically biaxial.

IMA symbol Pmarf, IMA status: approved, named in 2017.

Found in syenitic and granitic dikes the product of strongly peralkaline and potassic magma.

It is found associated with Quartz, potassium feldspar, aegirine-augite, quartz, zircon, magnetite, ilmenite, titanite; hematite, pyrite, galena.

Signifies an amphibole of the arfvedsonite group with dominant Mg2+ in the C site and dominant K+ in the A site.

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 P minerals or help write this entry.