metamorphic
Foliated metamorphic rock, likely slate or phyllite
Slate–phyllite; primarily quartz, mica, and clay-derived minerals
AI-generated identification · may be incorrectFine-grained, gray-green, thinly layered and strongly foliated, with dull to silky luster; hardness about 3–5. It splits along planar cleavage and may contain weathering stains, moss, and iron-oxide patches.
Identified More metamorphic →
Explore Foliated metamorphic rock, likely slate or phyllite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Fine-grained, gray-green, thinly layered and strongly foliated, with dull to silky luster; hardness about 3–5. It splits along planar cleavage and may contain weathering stains, moss, and iron-oxide patches.
Formation & geological history
Formed when shale or mudstone underwent low-grade regional metamorphism, realigning clay minerals into cleavage; commonly Paleozoic to Precambrian in age, depending on location.
Uses & applications
Used locally for roofing, paving, landscaping, wall stone, and aggregate; attractive phyllite may be collected but is generally low-value.
Geological facts
Slate has very flat, sharp cleavage surfaces, while phyllite has a satiny sheen and slightly wavy foliation. The photographed outcrop appears weathered and may represent a foliated slate/phyllite transition.
Field identification & locations
Common in metamorphic belts worldwide, including the Appalachian Mountains, Wales, and New England. Identify it by thin planar splitting, fine grain, and aligned mica sheen; distinguish it from shale by its more pronounced cleavage and recrystallized texture.
More like this
