metamorphic
Likely slate or fine-grained metamorphic rock
Slate/phyllite; predominantly fine-grained mica, chlorite, and quartz
AI-generated identification · may be incorrectDark gray, dull to slightly silky luster, very fine-grained, with visible planar foliation and possible cleavage; hardness about 2.5–4 Mohs. The specimen appears dense and irregularly foliated, but the image is insufficient for a definitive identification.
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, dull to slightly silky luster, very fine-grained, with visible planar foliation and possible cleavage; hardness about 2.5–4 Mohs. The specimen appears dense and irregularly foliated, but the image is insufficient for a definitive identification.
Formation & geological history
Formed when shale or mudstone underwent low-grade regional metamorphism, typically during mountain building. Such rocks commonly formed hundreds of millions of years ago, depending on locality.
Uses & applications
Slate is used for roofing, floor tiles, paving, writing surfaces, and decorative stone; attractive pieces may be collected as geological specimens.
Geological facts
The strong planar cleavage reflects alignment of microscopic clay minerals and mica. Phyllite is a slightly more metamorphosed, silkier-looking relative of slate.
Field identification & locations
Look for thin, planar splitting, a very fine texture, and a gray-to-black color; a streak test, hand lens, and examination of cleavage would help distinguish slate from phyllite or schist. Common in ancient folded mountain belts worldwide.
More like this
