igneous
Likely weathered granite or granitic gneiss fragment
Granite; mainly quartz, feldspar, and mica
AI-generated identification · may be incorrectSmall, irregular, tan-gray specimen with a dull to slightly granular luster and no obvious crystal faces. Typical granite hardness is about 6–7 Mohs; cleavage is mainly in feldspar, and specific gravity is roughly 2.6–2.7.
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Physical properties
Small, irregular, tan-gray specimen with a dull to slightly granular luster and no obvious crystal faces. Typical granite hardness is about 6–7 Mohs; cleavage is mainly in feldspar, and specific gravity is roughly 2.6–2.7.
Formation & geological history
Formed when silica-rich magma cooled slowly underground, producing interlocking quartz and feldspar crystals; regional glacial transport and weathering are plausible near 46.7°N, 92.0°W. Exact age cannot be determined from the photograph.
Uses & applications
Common granite is used as crushed aggregate, building stone, monuments, and landscaping; this small fragment has negligible commercial value.
Geological facts
The image is somewhat low-detail, so quartz-rich sandstone, weathered feldspar, or a concrete fragment are possible alternatives. The regional geology strongly supports glacially transported granitic material.
Field identification & locations
Look for visible interlocking grains: glassy gray quartz, white or pink feldspar, and dark mica. A streak test should be white; granite generally does not fizz with dilute hydrochloric acid. Common around glacial deposits and bedrock exposures in northeastern Minnesota.
