metamorphic
Likely slate
Slate, a fine-grained metamorphic rock composed mainly of mica-group minerals, quartz, and chlorite
AI-generated identification · may be incorrectDark gray, fine-grained, with a dull to slightly reflective surface and flat splitting; typical hardness is about 3–4 Mohs. The thin, plate-like shape and visible fine foliation are consistent with slate, though the image alone cannot confirm the identification.
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Physical properties
Dark gray, fine-grained, with a dull to slightly reflective surface and flat splitting; typical hardness is about 3–4 Mohs. The thin, plate-like shape and visible fine foliation are consistent with slate, though the image alone cannot confirm the identification.
Formation & geological history
Forms when shale or mudstone is subjected to low-grade regional metamorphism, developing slaty cleavage. It commonly dates from Paleozoic or older rocks, depending on the deposit.
Uses & applications
Used for roofing, flooring, paving, tiles, and decorative or craft pieces; this small fragment has little commercial value.
Geological facts
Slate’s cleavage lets it split into thin, durable sheets; the sparkly grains may be mica.
Field identification & locations
Look for fine grain, planar foliation, and sheets that split into flat pieces; common sources include Wales, Spain, and parts of the northeastern United States. Similar-looking phyllite or manufactured stone may be hard to distinguish from a photo.
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