metamorphic
Likely slate or fine-grained metamorphic rock
Slate–phyllite spectrum; commonly quartz, mica, and chlorite
AI-generated identification · may be incorrectDark gray, fine-grained, dull to slightly silky luster, with irregular planar cleavage visible along broken surfaces. Typical hardness is about 3–5 Mohs; exact identification is limited by the single photograph.
Identified More metamorphic →
Explore Likely slate or fine-grained metamorphic rock in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray, fine-grained, dull to slightly silky luster, with irregular planar cleavage visible along broken surfaces. Typical hardness is about 3–5 Mohs; exact identification is limited by the single photograph.
Formation & geological history
Formed when shale or mudstone undergoes low-grade regional metamorphism, commonly during mountain building. Its age depends on the source formation and cannot be determined visually.
Uses & applications
Used for roofing, floor and wall tiles, paving, writing slates, and decorative stone; attractive pieces may be collected but are usually low value.
Geological facts
Slate splits into thin sheets, whereas phyllite has a more pronounced silky sheen and wavy foliation. The specimen appears rough and naturally fractured rather than polished.
Field identification & locations
Look for consistent foliation, easy splitting, very fine grains, and absence of visible large crystals; a streak test, hardness test, and inspection of cleavage would help distinguish slate from shale, schist, or basalt. Common worldwide in metamorphic belts.
More like this
