![Arfvedsonite in Quartz (also labeled as Astrophyllite or Nuummite by collectors) ([Na][Na2][Mg4Fe2+](Si8O22)(OH)2 in SiO2) — metamorphic](https://media.rockidentification.com/21eb8d1a-62f9-442d-86b6-f3bfd72c09c0-compressed.jpg)
metamorphic
Arfvedsonite in Quartz (also labeled as Astrophyllite or Nuummite by collectors)
[Na][Na2][Mg4Fe2+](Si8O22)(OH)2 in SiO2
Hardness: 5.5-6 (mineral) to 7 (matrix); Color: Dark blue-black to charcoal with flashes of blue or silver; Luster: Vitreous to sub-metallic; Crystal structure: Monoclinic bladed needles; Specific gravity: approx 3.0-3.5
- Hardness
- 5
- Color
- Dark blue-black to charcoal with flashes of blue or silver
- Luster
- Vitreous to sub-metallic
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Physical properties
Hardness: 5.5-6 (mineral) to 7 (matrix); Color: Dark blue-black to charcoal with flashes of blue or silver; Luster: Vitreous to sub-metallic; Crystal structure: Monoclinic bladed needles; Specific gravity: approx 3.0-3.5
Formation & geological history
Formed in alkaline igneous rocks like plutonic syenites or high-grade metamorphic environments. Arfvedsonite crystallization often occurs during the late stages of magmatic differentiation.
Uses & applications
Primarily used as a decorative stone for lapidary work, including cabochons, tumbled stones, and metaphysical 'healing' crystals.
Geological facts
It is frequently misidentified as Astrophyllite or Nuummite due to its dark appearance and shimmering inclusions. Its blue-toned 'flash' is distinct from the bronze/gold flash of true Astrophyllite.
Field identification & locations
Identify by looking for dark, needle-like bladed inclusions that catch the light at specific angles. Commonly sourced from Greenland, Russia (Kola Peninsula), and Canada. In the field, look for its association with nepheline syenites.
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