igneous
Labradorite (Larvikite variety)
Ternary feldspar (Anorthoclase), (Na,K)AlSi3O8
Hardness: 6-6.5 (Mohs scale); Color: Dark grey to black with blue or silver iridescent flashes; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific Gravity: 2.58-2.62
- Hardness
- 6-6
- Color
- Dark grey to black with blue or silver iridescent flashes
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6-6.5 (Mohs scale); Color: Dark grey to black with blue or silver iridescent flashes; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific Gravity: 2.58-2.62
Formation & geological history
Formed from the cooling of magmatic intrusions during the Permian period, approximately 290 million years ago. It crystallizes in deep-seated plutonic environments as a monzonitic rock.
Uses & applications
Extensively used as an ornamental stone in architecture for countertops and building facades. Also popular in jewelry and for decorative polished specimens or palm stones.
Geological facts
Often marketed as 'Blue Pearl Granite' or 'Black Moonstone,' although it is technically a feldspar-rich monzonite. The characteristic blue flash is known as the Schiller effect or labradorescence.
Field identification & locations
Identify by rotating it under light to see internal blue or silver flashes (labradorescence). Most common in the Oslo region of Norway. Collectors should look for high-contrast flashes and minimal cracking.
