metamorphic

Dark slate pebble

Slate, predominantly fine-grained mica and clay-derived minerals

AI-generated identification · may be incorrect

Typically dark gray to black, very fine-grained, with a dull to silky luster and strong slaty cleavage; Mohs hardness about 3–4, with low-to-moderate specific gravity (~2.7–2.8). The visible parallel layering and platy fracture are characteristic.

Identified September 11, 2026More metamorphic →

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Physical properties

Formation & geological history

Slate forms when shale or mudstone undergoes low-grade regional metamorphism, commonly during mountain building; its exact age depends on the source formation. This appears naturally rounded or manually smoothed, likely from weathering or tumbling.

Uses & applications

Used for roofing, paving, floor tiles, wall cladding, writing tablets, landscaping, and decorative stones; this small piece has modest collecting or craft value.

Geological facts

Slate’s cleavage allows it to split into thin, durable sheets. Dark coloration commonly reflects carbonaceous matter, iron minerals, or graphite-like impurities.

Field identification & locations

Identify it by its fine texture, planar foliation, dark color, and ability to split into flat flakes; common occurrences include metamorphic belts worldwide, especially Wales, Spain, India, and the northeastern United States.