metamorphic
Rounded gray metamorphic pebble, likely gneiss or granitic rock
Probable quartz–feldspar–mica gneiss; exact identification requires a fresh surface and testing
AI-generated identification · may be incorrectMedium gray, granular and weakly foliated, with a dull to slightly sparkling luster; likely hardness 6–7 Mohs, no obvious cleavage, and specific gravity about 2.6–2.8. Rounded edges indicate water transport or abrasion.
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Physical properties
Medium gray, granular and weakly foliated, with a dull to slightly sparkling luster; likely hardness 6–7 Mohs, no obvious cleavage, and specific gravity about 2.6–2.8. Rounded edges indicate water transport or abrasion.
Formation & geological history
Likely formed by high-grade metamorphism of a granitic or sedimentary protolith, with quartz, feldspar, and mica recrystallizing under heat and pressure; age cannot be determined visually and may range from Precambrian to younger. It was probably collected from a gravel or stream deposit.
Uses & applications
Commonly used as landscaping gravel, aggregate, paving stone, and decorative rock; attractive pieces may be used as craft or display specimens. This small, ordinary pebble has little commercial value.
Geological facts
The pale speckled texture reflects interlocking quartz and feldspar grains, while darker streaks may be biotite or amphibole. A glass scratch test and examination of a broken face can help distinguish it from quartzite or granite.
Field identification & locations
Common in glaciated and mountainous regions worldwide, especially areas underlain by Precambrian basement or granitic rocks. Look for mineral grains, faint foliation, and resistance to scratching by steel; value is typically $1–$5, or under $10 for an unusually attractive specimen.
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