igneous
Likely weathered granite or granitic gneiss fragment
Granite: quartz + feldspar + mica; possibly gneiss if foliation is confirmed
AI-generated identification · may be incorrectSmall, irregular gray-brown fragment with a granular texture and scattered light/dark grains. Likely hardness about 6–7 Mohs, vitreous to dull luster, no obvious cleavage as a whole rock; exact minerals are uncertain from the blurred image.
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Physical properties
Small, irregular gray-brown fragment with a granular texture and scattered light/dark grains. Likely hardness about 6–7 Mohs, vitreous to dull luster, no obvious cleavage as a whole rock; exact minerals are uncertain from the blurred image.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep underground; gneiss forms when such rock is metamorphosed under high heat and pressure. Precambrian granitic and metamorphic rocks are widespread around northeastern Minnesota, near 46.7°N, 92.0°W.
Uses & applications
Commonly used as crushed stone, aggregate, building stone, and landscaping material; this small fragment has negligible commercial value.
Geological facts
The specimen is too small and visually indistinct for a confident species-level identification. A fresh broken surface would better reveal quartz, feldspar, and mica grains.
Field identification & locations
Likely regional glacial-transported bedrock or local road/landscaping debris. Look for interlocking grains: glassy gray quartz, white/pink feldspar, and black mica; a streak test is generally unhelpful. A magnet test may detect minor magnetite.
