metamorphic

Tumbled bronzite-rich metamorphic rock

Likely bronzite-bearing serpentinite or norite; exact identification requires testing

AI-generated identification · may be incorrect

Brown to bronze-black, strongly polished, with streaky granular texture and weak silky-to-vitreous luster. Likely hardness about 5–6 Mohs if bronzite-rich; bronzite is orthorhombic pyroxene with two cleavages, while serpentinite is softer (2.5–5).

Identified September 5, 2026More metamorphic →

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Physical properties

Formation & geological history

Probably formed through metamorphism or alteration of magnesium- and iron-rich ultramafic rock; age depends on its source locality and cannot be determined visually. The rounded shape and gloss indicate human tumbling and polishing.

Uses & applications

Used mainly as a decorative or lapidary stone, cabochon, carving, or collector specimen; not generally a construction stone in this form.

Geological facts

Bronzite produces characteristic bronze chatoyancy or reflective flashes when polished. Similar-looking stones include tiger iron, mahogany obsidian, jasper, and polished amphibolite.

Field identification & locations

Identify by bronze reflective patches, dark streaks, and a granular rather than glassy texture; a streak test, hardness test, magnetism, and specific-gravity measurement would help distinguish candidates. Common sources include ultramafic terrains in the United States, Canada, Brazil, India, and Australia.