metamorphic
Nuummite
Nuummite (ortho-amphibole rock)
Hardness: 5.5-6 (Mohs scale), Color: Black to dark brown with flecks of gold, blue, or green iridescence, Luster: Vitreous to pearly, Crystal structure: Orthorhombic, Cleavage: Perfect, Specific Gravity: 2.85-3.57
- Hardness
- 5
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Physical properties
Hardness: 5.5-6 (Mohs scale), Color: Black to dark brown with flecks of gold, blue, or green iridescence, Luster: Vitreous to pearly, Crystal structure: Orthorhombic, Cleavage: Perfect, Specific Gravity: 2.85-3.57
Formation & geological history
Formed through high-grade metamorphism over 3 billion years ago during the Archean age, primarily found in volcanic terrains in Nuuk, Greenland.
Uses & applications
Used primarily in lapidary work for jewelry (cabochons), ornamental carvings, and specifically as decorative polished towers or points for mineral collectors.
Geological facts
Known as one of the oldest rocks on Earth, it was first discovered in 1810 by the mineralogist K. L. Giesecke. It is characterized by 'labradorescence-like' shifts in color due to the mixture of gedrite and anthophyllite.
Field identification & locations
Identify by its dark body color and characteristic 'flash' or schiller effect from the needle-like amphibole crystals. Primarily sourced from Greenland; similar materials from Norway and China are often sold but differ geologically.
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