metamorphic

Foliated metamorphic rock, likely slate or phyllite

Slate–phyllite; composition commonly quartz, mica, and chlorite

AI-generated identification · may be incorrect

Gray-green, fine-grained, dull to silky luster, with closely spaced planar cleavage and thin platy splitting. Typical hardness is about 3–5 Mohs; individual mineral grains are too fine to identify confidently from the photograph.

Identified September 8, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or mudstone undergoes low-grade regional metamorphism during mountain building, commonly over millions of years. Exact age and grade require laboratory examination.

Uses & applications

Used for roofing, flooring, wall cladding, paving, and writing slates; attractive phyllite may be used decoratively. This ordinary fragment has little commercial or collector value.

Geological facts

Slate has very fine, flat cleavage surfaces, while phyllite commonly shows a subtle satiny sheen from aligned mica. The specimen appears more phyllitic or slate-like than igneous.

Field identification & locations

Look for consistent cleavage, fine grains, and splitting into sheets; a streak test, hand lens, and fresh-break examination help distinguish it from shale. Common in metamorphic belts worldwide, including the Appalachians, Wales, Spain, and India.