igneous
Blue-gray quartz-rich rock, likely sodalite-bearing syenite or granite
Probable sodalite-bearing nepheline syenite; composition may include quartz, feldspar, sodalite, and dark mafic minerals
AI-generated identification · may be incorrectHardness approximately 5.5–7 Mohs; mottled blue-gray to white with a dull to slightly vitreous luster and coarse granular texture. Individual crystals are poorly defined, with no obvious cleavage visible; exact identification requires testing.
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Physical properties
Hardness approximately 5.5–7 Mohs; mottled blue-gray to white with a dull to slightly vitreous luster and coarse granular texture. Individual crystals are poorly defined, with no obvious cleavage visible; exact identification requires testing.
Formation & geological history
Likely formed by slow cooling of silica-poor alkaline magma, producing interlocking feldspar and sodalite crystals; age is indeterminate from the photograph. Comparable rocks occur in alkaline igneous complexes worldwide.
Uses & applications
Used mainly as a decorative stone, ornamental specimen, or lapidary material; blue sodalite-rich varieties may be cut and polished, though this piece appears rough and low-grade.
Geological facts
The blue coloration commonly comes from sodalite, while white areas are usually feldspar. It could also be a blue-gray metamorphic or altered rock, so visual identification alone is not definitive.
Field identification & locations
Check for a granular crystalline texture, blue sodalite, white feldspar, and hardness sufficient to scratch glass; a streak, acid, magnetism, and thin-section/XRF test would help distinguish alternatives. Common sources include Canada, Brazil, Russia, and Greenland.
