igneous
Likely weathered granite or granitic pebble
Granite; typically quartz, feldspar, and mica (approx. SiO₂-rich plutonic rock)
AI-generated identification · may be incorrectCoarse-grained, mottled gray-brown and purple, with a dull to slightly sparkly luster; individual mineral grains are visible. Typical granite hardness is about 6–7 Mohs, with poor cleavage as a rock and density around 2.6–2.8 g/cm³.
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Physical properties
Coarse-grained, mottled gray-brown and purple, with a dull to slightly sparkly luster; individual mineral grains are visible. Typical granite hardness is about 6–7 Mohs, with poor cleavage as a rock and density around 2.6–2.8 g/cm³.
Formation & geological history
Forms when silica-rich magma cools slowly deep underground, allowing large crystals to grow; ages commonly range from tens of millions to over 3 billion years. The rounded shape indicates transport and weathering, likely in a stream or gravel deposit.
Uses & applications
Used extensively as building stone, countertops, monuments, aggregate, and decorative landscaping rock; small specimens have modest collecting value.
Geological facts
The purple tones may reflect potassium feldspar, while dark flecks are likely biotite or hornblende. The image is insufficient to distinguish granite confidently from related rocks such as granodiorite or gneiss.
Field identification & locations
Look for interlocking visible grains of pale quartz, pink/gray feldspar, and dark mica; a steel nail should not scratch it easily. Common worldwide, especially in exposed continental shields and mountain belts.
