mineral

Arfvedsonite

Arfvedsonite [Na3(Fe2+)4Fe3+Si8O22(OH)2]

Hardness: 5.5-6 (Mohs scale); Color: Black with blue or silver flashes of chatoyancy; Luster: Vitreous to sub-metallic; Crystal structure: Monoclinic; Cleavage: Perfect amphibole cleavage at 56 and 124 degrees.

Hardness: 5
Color: Black with blue or silver flashes of chatoyancy
Luster: Vitreous to sub-metallic

Identified May 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in alkaline igneous rocks like nepheline syenites and granitic pegmatites through the crystallization of sodium-rich magma. Commonly associated with aegirine and various feldspars.

Uses & applications

Primarily used as a collector specimen, for lapidary work (cabs and tumbled stones), and occasionally in metaphysical or holistic practices.

Geological facts

Often confused with Astrophyllite or Nuummite, it is named after the Swedish chemist Johan August Arfwedson who discovered lithium. The blue flashes are caused by its crystal structure reflecting light.

Field identification & locations

Identified by its specific dark color and the needle-like or bladed blue iridescent inclusions. It is found in localities such as Greenland, Russia, Canada (Mont Saint-Hilaire), and Norway.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral