igneous
Rounded gray river pebble, likely granite or gneiss
Indeterminate granitic rock; commonly quartz + feldspar + mica, possibly gneissic
AI-generated identification · may be incorrectHardness about 6–7 Mohs; smooth, water-worn surface; gray with whitish and brown mineral patches; dull to weakly sparkly luster. Massive or weakly foliated texture; no obvious cleavage as a whole rock.
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Physical properties
Hardness about 6–7 Mohs; smooth, water-worn surface; gray with whitish and brown mineral patches; dull to weakly sparkly luster. Massive or weakly foliated texture; no obvious cleavage as a whole rock.
Formation & geological history
Likely weathered from an old continental igneous or metamorphic outcrop and rounded by stream or beach transport. The image cannot establish its geological age, but granitic rocks commonly range from Precambrian to recent.
Uses & applications
Used mainly as a decorative pebble, landscaping stone, craft material, or paperweight; not typically valuable as jewelry.
Geological facts
The brown areas may be iron-stained feldspar or biotite/hornblende alteration. A fresh broken surface showing translucent quartz, pink/white feldspar, and dark mica would support a granitic identification.
Field identification & locations
Common worldwide in streambeds, beaches, gravel deposits, and glacial sediments. Identify with a hand lens and streak-free surface: visible interlocking grains and hardness sufficient to scratch glass suggest granite/gneiss; strong banding would favor gneiss.
