igneous
Weathered granite or granitic gneiss
Granite; primarily quartz, feldspar, and mica, with possible iron-oxide weathering
AI-generated identification · may be incorrectCoarse, mottled brown-gray stone with a granular texture and dull-to-waxy luster; likely Mohs hardness 6–7, with no obvious cleavage as a whole rock. Individual feldspar grains may show cleavage, while quartz is glassy and hard.
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Physical properties
Coarse, mottled brown-gray stone with a granular texture and dull-to-waxy luster; likely Mohs hardness 6–7, with no obvious cleavage as a whole rock. Individual feldspar grains may show cleavage, while quartz is glassy and hard.
Formation & geological history
Likely formed by slow cooling of silica-rich magma deep in Earth’s crust; if banding or foliation is confirmed, it may instead be metamorphic gneiss. The specimen’s exact age and locality cannot be determined from the image.
Uses & applications
Common granite is used as crushed aggregate, building stone, countertops, monuments, and landscaping material; ordinary hand specimens have little commercial value.
Geological facts
The brown color is commonly caused by weathered iron-bearing minerals or stained feldspar. Dark patches may represent biotite, hornblende, or localized alteration.
Field identification & locations
Identify it by visible interlocking quartz and feldspar grains, scattered dark mica/amphibole, and hardness sufficient to scratch glass. Common worldwide, especially in continental shields and mountain belts.
