igneous
Weathered granite (likely pegmatitic granite)
Granite; predominantly quartz (SiO₂), feldspar, and mica, with iron-oxide weathering
AI-generated identification · may be incorrectCoarse-grained, pale gray to pink and rusty brown, with a rough granular texture and dull to vitreous mineral luster. Typical hardness is about 6–7 Mohs; no overall cleavage, though feldspar and mica grains cleave individually; density is roughly 2.6–2.7 g/cm³.
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Physical properties
Coarse-grained, pale gray to pink and rusty brown, with a rough granular texture and dull to vitreous mineral luster. Typical hardness is about 6–7 Mohs; no overall cleavage, though feldspar and mica grains cleave individually; density is roughly 2.6–2.7 g/cm³.
Formation & geological history
An intrusive igneous rock formed by slow cooling of silica-rich magma deep underground, commonly during Precambrian to Phanerozoic plutonic events. The orange-brown areas are likely surface oxidation of iron-bearing minerals and weathering along fractures.
Uses & applications
Used extensively as dimension stone, paving, aggregate, monuments, and countertops; attractive polished pieces are also collected decoratively. This specimen appears too weathered and ordinary for significant gem value.
Geological facts
Granite commonly contains interlocking quartz and feldspar crystals large enough to see without magnification. Its rusty coating can result from oxidation of biotite, amphibole, or pyrite-bearing zones.
Field identification & locations
Identify it by visible interlocking grains, abundant light feldspar/quartz, and occasional dark mica flakes; a steel scratch test should not easily scratch fresh quartz grains. Common worldwide in continental shields and mountain batholiths, including North America, Europe, India, and Australia.
