mineral

Arfvedsonite in Matrix

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

Hardness: 5-6; Color: Black with dark blue/green flashes; Luster: Vitreous to sub-metallic; Crystal structure: Monoclinic; Cleavage: Perfect at 56 and 124 degrees; Specific gravity: 3.44-3.50

Hardness: 5-6
Color: Black with dark blue/green flashes
Luster: Vitreous to sub-metallic

Identified March 26, 2026More mineral →

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Physical properties

Hardness: 5-6; Color: Black with dark blue/green flashes; Luster: Vitreous to sub-metallic; Crystal structure: Monoclinic; Cleavage: Perfect at 56 and 124 degrees; Specific gravity: 3.44-3.50

Formation & geological history

Formed in highly alkaline plutonic igneous rocks, such as nepheline syenites and agpaitic pegmatites. It forms from the late-stage crystallization of sodium-rich magma. Key deposits range from Proterozoic to Cenozoic eras.

Uses & applications

Primarily used as a lapidary material for jewelry (cabochons and beads) and as a display specimen for mineral collectors. It is often used in metaphysical practices for its purported 'insight' properties.

Geological facts

Arfvedsonite is often confused with Astrophyllite or Nuummite due to its dark appearance and internal flashes. It was named after the Swedish chemist Johan August Arfwedson, who discovered the element Lithium.

Field identification & locations

Identify in the field by its dark, blade-like crystals and distinctive bluish-green pleochroism/flash when polished. Commonly found in Greenland (Ivigtut), Canada (Mont Saint-Hilaire), Russia (Kola Peninsula), and the USA (New Hampshire).

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