![Arfvedsonite in Quartz (Arfvedsonite [Na3(Fe2+4Fe3+)Si8O22(OH)2] often hosted in Quartz or Feldspar) — igneous](https://media.rockidentification.com/984aac15-a470-4df2-8c41-42a89e4b6425-compressed.jpg)
igneous
Arfvedsonite in Quartz
Arfvedsonite [Na3(Fe2+4Fe3+)Si8O22(OH)2] often hosted in Quartz or Feldspar
Hardness: 5.5-6 (Arfvedsonite) / 7 (Quartz); Color: Black fibers/streaks in a white or light gray matrix; Luster: Vitreous to sub-metallic; Crystal Structure: Monoclinic; Specific Gravity: 3.44 (Arfvedsonite)
- Hardness
- 5
- Color
- Black fibers/streaks in a white or light gray matrix
- Luster
- Vitreous to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 5.5-6 (Arfvedsonite) / 7 (Quartz); Color: Black fibers/streaks in a white or light gray matrix; Luster: Vitreous to sub-metallic; Crystal Structure: Monoclinic; Specific Gravity: 3.44 (Arfvedsonite)
Formation & geological history
Formed in highly alkaline igneous rocks such as syenite and granite pegmatites. It crystallizes from late-stage magmatic fluids rich in sodium and iron.
Uses & applications
Primarily used as a metaphysical stone, for lapidary work (towers, spheres), and as a collector's specimen.
Geological facts
Arfvedsonite is often mistaken for Astrophyllite or Nuummite due to its dark, bladed appearance, but it is distinctively an amphibole mineral. It was named after the Swedish chemist Johan August Arfwedson.
Field identification & locations
Identify by its dark blue-black to black needle-like or bladed crystals often showing a slight blue flash when polished. Found commonly in Greenland, Russia (Kola Peninsula), and Canada.
