metamorphic
Polished blue-gray stone, likely labradorite or gneiss
Labradorite-bearing gneiss; plagioclase feldspar-rich rock
AI-generated identification · may be incorrectDark blue-gray, fine- to medium-grained, with pale reflective streaks and weak bluish schiller; likely Mohs 6–6.5, vitreous to dull luster, no obvious cleavage visible, and specific gravity about 2.7–2.9.
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Physical properties
Dark blue-gray, fine- to medium-grained, with pale reflective streaks and weak bluish schiller; likely Mohs 6–6.5, vitreous to dull luster, no obvious cleavage visible, and specific gravity about 2.7–2.9.
Formation & geological history
If gneiss, it formed by high-grade metamorphism of feldspar-rich igneous or sedimentary rock, commonly during Precambrian orogenic events. The specimen appears cut or tumbled, so texture and layering are partly obscured.
Uses & applications
Used mainly as a decorative stone, cabochon, pendant, or collector specimen; larger labradorite-bearing rocks can be used for architectural facing and countertops.
Geological facts
The blue flash typical of labradorite is caused by light interference within thinly layered plagioclase domains, called labradorescence.
Field identification & locations
Common sources include Madagascar, Finland, Norway, Canada, and the United States. A strong angle-dependent blue or multicolor flash supports labradorite; visible compositional banding and granular texture support gneiss. A definitive identification requires a fresh surface or mineral tests.
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