metamorphic
Nuummite
Antophyllite-Gedrite Orthoamphibole (Mg,Fe)7Si8O22(OH)2
Hardness: 5.5-6.0 Mohs; Color: Black with iridescent flashes of gold, blue, or green; Luster: Vitreous to sub-metallic; Crystal Structure: Orthorhombic; Cleavage: Perfect; Specific Gravity: 2.8-3.0.
- Hardness
- 5
- Color
- Black with iridescent flashes of gold, blue, or green
- 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, or green; Luster: Vitreous to sub-metallic; Crystal Structure: Orthorhombic; Cleavage: Perfect; Specific Gravity: 2.8-3.0.
Formation & geological history
Formed through high-grade regional metamorphism of igneous rocks. It is one of the oldest rocks on Earth, dating back approximately 3 billion years to the Archean Eon. Primarily found in Greenland.
Uses & applications
Predominantly used as a gemstone for jewelry (cabochons), ornamental carvings, and by mineral collectors due to its rare iridescence and extreme age.
Geological facts
Known as the Sorcerer's Stone, it was discovered in 1982 in the Nuuk region of Greenland. It is unique for its lamellar structure which causes iris-like flashes of light known as labradorescence.
Field identification & locations
Identify by its distinct gold-colored 'flecks' or needle-like inclusions against a deep black background when rotated under light. Mostly found in the remote coastal areas of Greenland accessible only by boat.
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