metamorphic
Tumbled brown river stone
Likely weathered iron-rich basalt, greenstone, or other mafic metamorphic rock; exact identification requires testing
AI-generated identification · may be incorrectDark brown to gray mottling with subtle greenish areas and a dull-to-waxy luster; fine-grained, rounded, and polished by abrasion. Typical hardness is about 5–7 Mohs, with no visible cleavage and likely moderate-to-high density.
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Physical properties
Dark brown to gray mottling with subtle greenish areas and a dull-to-waxy luster; fine-grained, rounded, and polished by abrasion. Typical hardness is about 5–7 Mohs, with no visible cleavage and likely moderate-to-high density.
Formation & geological history
Probably formed from mafic volcanic rock and later altered or metamorphosed, then rounded by river or beach transport; its geological age cannot be determined from the photograph.
Uses & applications
Suitable as a decorative hand specimen, worry stone, landscaping stone, or craft material; it has little commercial value unless laboratory testing reveals a distinctive mineral such as jade.
Geological facts
The smooth shape and subdued surface are characteristic of prolonged natural water abrasion or tumbling. Brown coloration commonly reflects iron-oxide staining or weathering.
Field identification & locations
Look for a dense, fine-grained texture, absence of vesicles, and a streak or freshly broken surface; hardness, specific gravity, magnetism, and thin-section analysis would distinguish basalt, greenstone, and jade-like rocks. Commonly found in river gravels and glacial deposits.
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