igneous
Tumbled epidote-bearing granite or amphibolite
Quartz–feldspar rock with dark amphibole/biotite and epidote; exact identification is uncertain from the image
AI-generated identification · may be incorrectOrange-brown, strongly polished surface with black-green elongated mineral bands and pale translucent grains; likely Mohs hardness 6–7, vitreous to dull luster, massive granular texture, and no obvious cleavage. The orange color may reflect iron-stained feldspar or altered quartz-rich material.
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Physical properties
Orange-brown, strongly polished surface with black-green elongated mineral bands and pale translucent grains; likely Mohs hardness 6–7, vitreous to dull luster, massive granular texture, and no obvious cleavage. The orange color may reflect iron-stained feldspar or altered quartz-rich material.
Formation & geological history
Likely an altered igneous rock formed by crystallization of magma, with later hydrothermal alteration producing epidote and iron staining; typical ages range from Precambrian to Mesozoic depending on locality. The rounded shape indicates human tumbling and polishing.
Uses & applications
Suitable mainly as a decorative or educational specimen, cabochon, or paperweight; not generally used commercially in this small form. Common material is inexpensive unless unusually attractive or locality-specific.
Geological facts
The dark streaks may be amphibole, biotite, magnetite, or epidote-rich alteration zones; distinguishing them requires a close examination, streak, hardness, and possibly thin-section or chemical testing.
Field identification & locations
Commonly encountered in metamorphic and altered igneous terrains worldwide, including the Alps, Scandinavia, North America, and Brazil. A hand lens, scratch test, magnet test, and specific-gravity measurement can refine identification.
