![Tumbled bronzite-bearing gneiss (likely) (Foliated silicate rock; chiefly orthopyroxene [(Mg,Fe)SiO₃], feldspar, quartz, and biotite) — metamorphic](https://media.rock.id/tumbled-bronzite-bearing-gneiss-likely-6aa25531-dac0-49cf-ba82-2a740b2cce2c-compressed.jpg)
metamorphic
Tumbled bronzite-bearing gneiss (likely)
Foliated silicate rock; chiefly orthopyroxene [(Mg,Fe)SiO₃], feldspar, quartz, and biotite
AI-generated identification · may be incorrectBrown, black, gray, and pink banding with a polished surface and subtle bronzy sheen; typically Mohs 5.5–7, granular crystalline texture, no prominent cleavage as a whole, and specific gravity about 2.7–3.4.
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Physical properties
Brown, black, gray, and pink banding with a polished surface and subtle bronzy sheen; typically Mohs 5.5–7, granular crystalline texture, no prominent cleavage as a whole, and specific gravity about 2.7–3.4.
Formation & geological history
Formed when quartzofeldspathic or mafic protoliths underwent high-grade metamorphism, producing compositional banding; commonly Precambrian, though exact age depends on source locality.
Uses & applications
Used as a decorative tumbled stone, cabochon, and lapidary material; large pieces may serve as ornamental stone but are not generally valuable construction rock.
Geological facts
The specimen appears strongly foliated and may be marketed as bronzite gneiss, “brown zebra stone,” or another trade name; exact identification requires microscopy or mineral testing.
Field identification & locations
Look for aligned mineral bands, hard dark grains, and a bronze-to-silky reflection from orthopyroxene or biotite. Common sources include India, Brazil, Madagascar, and Scandinavia; avoid confusing it with jasper or dyed stone.
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