metamorphic
Likely weathered mica-rich rock fragment
Probable schist, composed mainly of quartz, feldspar, and mica
AI-generated identification · may be incorrectSmall, rounded gray-green fragment with a sparkly, flaky surface, consistent with mica-bearing schist or phyllite. Mica has Mohs hardness about 2–3; quartz, if present, is about 7. Exact color, cleavage, and specific gravity cannot be confirmed from the blurred image.
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Physical properties
Small, rounded gray-green fragment with a sparkly, flaky surface, consistent with mica-bearing schist or phyllite. Mica has Mohs hardness about 2–3; quartz, if present, is about 7. Exact color, cleavage, and specific gravity cannot be confirmed from the blurred image.
Formation & geological history
Likely formed when mudstone or volcanic sediment was regionally metamorphosed, commonly during Precambrian or Paleozoic mountain-building. The Duluth–northeastern Minnesota region contains abundant metamorphic and igneous glacial erratics.
Uses & applications
Usually a collecting specimen; schist may be used locally as decorative stone or crushed aggregate, but this small piece has no significant commercial value.
Geological facts
The bright glitter is probably reflective mica flakes rather than metallic mineralization. Its rounded shape may result from glacial transport or stream abrasion.
Field identification & locations
Look for thin layers that split along shiny planes, a foliated texture, and visible mica flakes. A streak, hardness, and close-up photograph would help distinguish schist from phyllite, chlorite-rich rock, or mica-bearing granite.
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