igneous
Weathered granitic pebble
Likely biotite-bearing granite or granodiorite, dominated by quartz and feldspar
AI-generated identification · may be incorrectCoarse, mottled cream-gray rock with black biotite or amphibole and probable quartz; typically Mohs 6–7, vitreous to dull luster, interlocking crystalline texture, and no consistent cleavage. The rounded shape indicates substantial water or glacial abrasion and weathering.
Identified More igneous →
Explore Weathered granitic pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse, mottled cream-gray rock with black biotite or amphibole and probable quartz; typically Mohs 6–7, vitreous to dull luster, interlocking crystalline texture, and no consistent cleavage. The rounded shape indicates substantial water or glacial abrasion and weathering.
Formation & geological history
Formed when silica-rich magma slowly crystallized deep underground, commonly during Precambrian to Phanerozoic mountain-building events; its exact age cannot be determined from the image. Surface weathering has altered feldspar to pale clay-like material and rounded the specimen.
Uses & applications
Used widely as crushed aggregate, road stone, building stone, monuments, countertops, and landscaping material; this small specimen has mainly educational or modest collecting value.
Geological facts
Granite and granodiorite are plutonic rocks whose visible crystals record slow cooling beneath Earth’s surface. Dark flakes are likely biotite mica, while pale grains are feldspar and quartz.
Field identification & locations
Identify it by visible interlocking pale crystals, scattered black mica/amphibole, hardness sufficient to scratch glass, and lack of layering or fossils. Common in continental mountain belts and glacial or stream gravels worldwide.
