igneous
Tumbled granitic rock, possibly granite pegmatite
Granite or granitic pegmatite; chiefly quartz, feldspar, and mica, with possible iron-oxide staining
AI-generated identification · may be incorrectCoarse crystalline, mottled white-gray with rusty orange and dark minerals; vitreous quartz, feldspathic luster, uneven fracture, and Mohs hardness about 6–7. The rounded shape indicates tumbling or natural abrasion.
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Physical properties
Coarse crystalline, mottled white-gray with rusty orange and dark minerals; vitreous quartz, feldspathic luster, uneven fracture, and Mohs hardness about 6–7. The rounded shape indicates tumbling or natural abrasion.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the crust, likely hundreds of millions to billions of years ago; later weathering and transport rounded the specimen.
Uses & applications
Common granitic material is used as crushed stone, aggregate, dimension stone, and decorative rock; attractive polished pieces are sold for tumbling and teaching collections.
Geological facts
Visible interlocking light crystals and dark inclusions are typical of granite; orange areas are likely oxidation of iron-bearing minerals. Exact identification requires a fresh surface or petrographic examination.
Field identification & locations
Look for distinct quartz, feldspar, and mica grains, no layering, and hardness sufficient to scratch glass. Granites occur widely worldwide, including the Sierra Nevada, New England, Scandinavia, India, and Brazil.
