IMA mineral species

Potassic-magnesio-fluoro-arfvedsonite

KNa₂(Mg₄Fe³⁺)Si₈O₂₂F₂

Na-amphibole, double chain inosilicate mineral.

Properties

⛏ Mohs hardness5 – 7

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💅🪙🍶🔪💎

Harder than quartz: scratches glass and steel.

🔷 Monoclinic✏️ streak white

Chemical formula	KNa₂(Mg₄Fe³⁺)Si₈O₂₂F₂
Elements	K, Na, Mg, Fe, Si, O, F
Crystal system	Monoclinic
Mohs hardness	5 – 7
Density	—
Streak	white
Color	—
Cleavage	{110}
IMA symbol	Pmfarf
Nickel–Strunz class	9.DE.25

“—” means no reliable value in Wikidata yet. Check Mindat for full data.

Learn more

Potassic-magnesio-fluoro-arfvedsonite on Mindat.org
Wikipedia article
Wikidata item Q18059147 (source of this page's data – you can correct it there)