metamorphic
Nuummite
Orthorhombic amphibole (Gedrite and Anthophyllite mixture) - (Mg,Fe)7Si8O22(OH)2
Hardness: 5.5-6 (Mohs). Color: Charcoal gray to black with iridescent flashes of gold, copper, blue, or green. Luster: Vitreous to sub-metallic on iridescence. Crystal Structure: Orthorhombic. Cleavage: Perfect in two directions.
- Hardness
- 5
- Luster
- Vitreous to sub-metallic on iridescence
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Physical properties
Hardness: 5.5-6 (Mohs). Color: Charcoal gray to black with iridescent flashes of gold, copper, blue, or green. Luster: Vitreous to sub-metallic on iridescence. Crystal Structure: Orthorhombic. Cleavage: Perfect in two directions.
Formation & geological history
Formed in the Archean era (approx. 2.8 billion years ago) through high-grade metamorphism. It is one of the oldest rocks on Earth, found primarily in Nuuk, Greenland.
Uses & applications
Predominantly used for ornamental purposes, carvings, jewelry (cabochons), and as a high-value collector's mineral due to its age and rarity.
Geological facts
Known as the "Sorcerer's Stone," it was only discovered in 1982. It takes its name from the municipality of Nuuk, where it was first found. Its distinct 'labradorescence-like' flash is caused by the intergrowth of two different minerals within the amphibole group.
Field identification & locations
Identify in the field by its dark matrix and 'fire-like' elongated iridescent needles. It is almost exclusively found in the rugged, remote terrain of Greenland, specifically around the Godthåbsfjord region. Authenticate by checking for the specific fibrous texture of the flashes.
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