metamorphic
Shale or slate fragment
Fine-grained phyllosilicate rock, likely slate (metamorphosed shale)
AI-generated identification · may be incorrectGray, dull to slightly silky luster with thin planar layers and excellent splitting; typical hardness is about 3–5. The visible piece appears fine-grained and foliated, but mineral identification is limited by the image.
Identified More metamorphic →
Explore Shale or slate fragment in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Gray, dull to slightly silky luster with thin planar layers and excellent splitting; typical hardness is about 3–5. The visible piece appears fine-grained and foliated, but mineral identification is limited by the image.
Formation & geological history
Slate forms when shale undergoes low-grade regional metamorphism, commonly during mountain-building; its age depends on the host formation and may range from Paleozoic to Precambrian. If it is unmetamorphosed shale, it formed as compacted mud in an ancient quiet-water basin.
Uses & applications
Used for roofing, flooring, paving, landscaping, and writing slates; ordinary fragments have little commercial or jewelry value.
Geological facts
Slate’s foliation reflects aligned microscopic clay minerals recrystallized into mica and chlorite. It breaks into thin, relatively flat sheets, unlike massive igneous rocks.
Field identification & locations
Look for consistent planar cleavage, fine grain, and gray, green, purple, or black coloration; a steel nail may scratch it. Common sources include metamorphic belts worldwide, while shale is widespread in sedimentary basins.
More like this
