igneous
Weathered granitic pebble
Granite to granodiorite, chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectTypically Mohs 6–7; pale gray-green, fine- to medium-grained, dull to weakly sparkling luster, with interlocking crystalline texture and no obvious cleavage as a whole. The rounded shape indicates water or abrasion wear; green coloration may reflect epidote, chlorite, or weathered minerals.
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Physical properties
Typically Mohs 6–7; pale gray-green, fine- to medium-grained, dull to weakly sparkling luster, with interlocking crystalline texture and no obvious cleavage as a whole. The rounded shape indicates water or abrasion wear; green coloration may reflect epidote, chlorite, or weathered minerals.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic plutonic events, then exposed and rounded by erosion. Exact identification and age require a fresh fracture or laboratory analysis.
Uses & applications
Common granitic material is used as crushed aggregate, building stone, monuments, and landscaping; this small specimen has mainly educational or modest collecting value.
Geological facts
Granite’s visible grains record slow underground cooling, unlike volcanic rocks that cool rapidly at the surface. Weathering can weaken feldspar and produce greenish alteration colors.
Field identification & locations
Look for interlocking quartz and feldspar grains, scattered dark mica, and hardness sufficient to scratch glass; dilute acid should not fizz. Common worldwide in eroded stream gravels and glacial deposits.
