igneous
Weathered granite (likely pegmatitic granite)
Granite; predominantly quartz (SiO₂), feldspar, and mica, with possible iron-oxide alteration
AI-generated identification · may be incorrectCoarse, irregular interlocking grains; pale gray, cream, tan, and reddish-brown colors with vitreous-to-dull luster. Quartz is Mohs 7, feldspar 6–6.5, mica 2–3; no consistent cleavage at the whole-rock scale, though feldspar and mica cleave readily.
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Physical properties
Coarse, irregular interlocking grains; pale gray, cream, tan, and reddish-brown colors with vitreous-to-dull luster. Quartz is Mohs 7, feldspar 6–6.5, mica 2–3; no consistent cleavage at the whole-rock scale, though feldspar and mica cleave readily.
Formation & geological history
Slow cooling of silica-rich magma several kilometers underground produced the crystalline texture; reddish-brown areas likely reflect surface weathering and iron oxidation. The exact geological age cannot be determined from an image and may range from Precambrian to recent intrusive bodies.
Uses & applications
Commonly used as building stone, countertops, paving, monuments, and aggregate; attractive pieces are collected as cabinet specimens, though this example appears ordinary and weathered.
Geological facts
Granite is a rock rather than a single mineral. Its visible large crystals indicate intrusive cooling, while rounded edges and discoloration suggest prolonged weathering.
Field identification & locations
Identify it by its speckled coarse grains, glassy quartz, blocky feldspar, and dark mica; it is commonly found in continental mountain belts and exposed plutons worldwide. A hand lens and fresh broken surface would improve identification.
