metamorphic
Nuummite
Antophyllite-Gedrite (Orthorhombic amphiboles)
Hardness: 5.5-6.0 Mohs; Color: Black with iridescent flashes of gold, blue, green, or red; Luster: Vitreous to sub-metallic; Crystal Structure: Orthorhombic; Cleavage: Perfect in two directions; Specific Gravity: 3.2-3.5
- Hardness
- 5
- Color
- Black with iridescent flashes of gold, blue, green, or red
- Luster
- Vitreous to sub-metallic
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Physical properties
Hardness: 5.5-6.0 Mohs; Color: Black with iridescent flashes of gold, blue, green, or red; Luster: Vitreous to sub-metallic; Crystal Structure: Orthorhombic; Cleavage: Perfect in two directions; Specific Gravity: 3.2-3.5
Formation & geological history
Formed through high-grade regional metamorphism of igneous protoliths. It is one of the oldest rocks on Earth, dating back approximately 3 billion years to the Archean Eon, primarily found in the Nuuk region of Greenland.
Uses & applications
Primarily used as a gemstone for jewelry (cabochons), ornamental carvings, and highly valued by mineral collectors and metaphysical practitioners.
Geological facts
Known as the 'Sorcerer's Stone,' Nuummite was first discovered in 1810 by the mineralogist K.L. Giesecke. Its unique 'labradorescence-like' flash is caused by the interference of light within the lamellar structure of the intergrown minerals.
Field identification & locations
Identify by its 'shimmering' effect against a dark, opaque background when rotated under light. It is found almost exclusively in Greenland, though some related amphiboles are found in Canada and Finland. Collectors should look for a distinct wood-grain pattern of iridescent needles.
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