metamorphic

Blue-gray metamorphic rock, possibly slate or phyllite

Likely quartz–mica-rich phyllite/slate; exact identification requires testing

AI-generated identification · may be incorrect

Blue-gray, fine-grained, dull to silky luster, with apparent layering/foliation and pale quartz-like patches. Typical hardness is about 2.5–4 for slate/phyllite, with good planar cleavage; density commonly 2.7–2.8 g/cm³.

Identified September 2, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when clay-rich sedimentary rock was subjected to low-grade regional metamorphism, recrystallizing into aligned mica and quartz. Such rocks commonly formed during Paleozoic or older mountain-building events, though age cannot be determined visually.

Uses & applications

Used for roofing, paving, flooring, and decorative stone when sound; attractive pieces may be collected, but this specimen has little gem value.

Geological facts

Phyllite commonly has a satiny sheen from microscopic mica, while slate is flatter and duller. The blue color may reflect chlorite, graphite, or other metamorphic minerals.

Field identification & locations

Look for splitting along foliation, fine grain, and mica sheen; a streak, hardness, acid, and close examination of cleavage would distinguish slate, phyllite, schist, or altered basalt. Common in metamorphic belts worldwide.