igneous
Weathered granitoid (likely granite or granodiorite)
Granite–granodiorite; primarily quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, pale gray to tan, with visible interlocking crystals and granular texture; quartz has Mohs hardness 7, feldspar 6, and mica 2–3. Typically nonfoliated, with poor cleavage overall and a specific gravity around 2.6–2.8.
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Physical properties
Coarse-grained, pale gray to tan, with visible interlocking crystals and granular texture; quartz has Mohs hardness 7, feldspar 6, and mica 2–3. Typically nonfoliated, with poor cleavage overall and a specific gravity around 2.6–2.8.
Formation & geological history
A plutonic igneous rock crystallized slowly from silica-rich magma deep within Earth, generally during continental crust formation; its exact geological age cannot be determined from the image. Surface weathering has rounded and altered the specimen.
Uses & applications
Used widely as crushed stone, aggregate, building stone, countertops, monuments, and occasionally architectural facing. This small weathered piece has little jewelry value.
Geological facts
The apparent dark cavity or inclusion may be a weathered mafic mineral, mica-rich pocket, or small secondary mineral cavity rather than a fossil. Granite and granodiorite are distinguished mainly by the relative abundance of quartz and potassium feldspar.
Field identification & locations
Look for visible quartz, white or pink feldspar, and black mica in a speckled, interlocking texture; it should scratch glass but not a steel knife if quartz is exposed. Common in continental mountain belts and glacial or stream gravel deposits.
