metamorphic
Likely foliated metamorphic rock (slate or phyllite)
Fine-grained, foliated rock; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectDark gray to black with wavy, pale foliation and a dull to slight silky sheen. Slate is very fine-grained and splits into flat sheets; phyllite has a more evident satiny sheen and crinkled foliation. Hardness and cleavage cannot be confirmed visually.
Identified More metamorphic →
Explore Likely foliated metamorphic rock (slate or phyllite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray to black with wavy, pale foliation and a dull to slight silky sheen. Slate is very fine-grained and splits into flat sheets; phyllite has a more evident satiny sheen and crinkled foliation. Hardness and cleavage cannot be confirmed visually.
Formation & geological history
Forms when clay-rich sedimentary rock is altered by low-grade metamorphism, producing aligned mica and other fine minerals. The image cannot establish its age or precise formation history.
Uses & applications
Slate is used for roofing, tiles, and paving; phyllite is used as decorative or landscaping stone and as a mineral specimen.
Geological facts
The undulating layers suggest foliation, but could also reflect uneven fracture or weathering; a close-up and fresh break would help distinguish slate from phyllite.
Field identification & locations
The dark foliated specimen is consistent with slate or phyllite, but the photo alone is not definitive. Near 22°S, 47.9°W in São Paulo state, regional geology includes metamorphic rocks, making this plausible; check for thin, planar splitting and a silky sheen.
More like this
