Arfvedsonite
Arfvedsonite (Sodium Amphibole) · Collector Mineral / Semi-Precious Gemstone
Crystal System
Monoclinic; often occurs in prismatic, fibrous, or bladed habits, though this specimen is carved into a polished star shape.
Mineral Group
Silicates; Inosilicate (Double-chain Amphibole group)
Chemical Formula
[Na][Na2][Mg4Fe2+](Si8O22)(OH)2 - often with manganese, calcium and potassium substitutions
Formation Process
Igneous formation; typically crystallizes in late-stage alkaline plutonic environments or pegmatites.
About This Crystal
Dark, nearly black to deep bluish-gray body color with distinctive silvery-blue or copper-colored bladed inclusions. It is opaque with a vitreous to sub-metallic luster on polished surfaces.
Physical Characteristics
Color is deep black to greenish-black; streak is dark bluish-gray. It has perfect cleavage at 56 and 124 degrees (typical of amphiboles) and a specific gravity of 3.44 - 3.45.
Optical Properties
High refractive index (1.65-1.70), strongly pleochroic (greenish-blue to brownish-yellow). Displays prominent silvery-blue chatoyancy or bladed flashes when light hits internal crystalline structures.
Hardness & Durability
Origin Region
Mont Saint-Hilaire (Canada), Kola Peninsula (Russia), Greenland, and Malawi. Found in alkaline igneous rocks like nepheline syenites.
Hardness & Durability
Mohs hardness of 5.5 to 6. Brittle tenacity. It is moderately durable but susceptible to scratches from harder minerals like quartz.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners and harsh chemicals. Store separately from harder gemstones to prevent surface abrasions.
Rarity & Value
Uncommon. Value is determined by the intensity of the blue flashes; often confused with Nuummite or Astrophyllite. It is generally affordable as polished specimens.
Special Characteristics
Displays 'flash' or chatoyant bladed structures similar to Labradorite but in a darker, more needle-like or radial formation. Responds to directional lighting.
Lore & History
Named after Swedish chemist Johan August Arfwedson. In metaphysical traditions, it is associated with the Throat and Third Eye chakras and is believed to aid in manifestation and reorganization of thoughts.