igneous
Weathered granite or granitic gneiss
Quartz–feldspar–mica granitic rock; possibly gneiss if foliation is present
AI-generated identification · may be incorrectLight gray to tan, coarse-grained, speckled, and dull to slightly gritty; likely Mohs 6–7, with quartz and feldspar crystals and minor dark mica. No clear crystal faces or cleavage are visible at this resolution.
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Physical properties
Light gray to tan, coarse-grained, speckled, and dull to slightly gritty; likely Mohs 6–7, with quartz and feldspar crystals and minor dark mica. No clear crystal faces or cleavage are visible at this resolution.
Formation & geological history
Formed by slow cooling of silica-rich magma deep underground, generally in Precambrian to younger continental crust; surface weathering has rounded and stained the specimen. If banded internally, it may be metamorphosed granite (gneiss).
Uses & applications
Granite is widely used as dimension stone, countertops, monuments, aggregate, and paving; ordinary hand specimens have little commercial value.
Geological facts
The pale grains are probably feldspar and quartz, while darker flecks are biotite or hornblende. Weathering commonly produces rounded edges and rusty iron-oxide staining.
Field identification & locations
Look for interlocking visible grains: translucent gray quartz, blocky white or pink feldspar, and black mica. Common worldwide, especially in continental mountain belts; a fresh broken surface and a streak-free scratch test help distinguish it from sandstone.
