sedimentary

Black Beach Pebble (Basalt / Slate Pebble)

Rounded Fine-Grained Clastic / Igneous Rock Pebble

Hardness: 3 to 6.5 depending on exact mineral composition; Color: Charcoal grey to dull black; Luster: Matte to earthy when dry, slightly glossy when wet; Texture: Fine-grained, smooth, water-worn edges; Cleavage: None visible due to rounding.

Hardness: 3 to 6
Color: Charcoal grey to dull black
Luster: Matte to earthy when dry, slightly glossy when wet

Identified July 26, 2026More sedimentary →

Explore Black Beach Pebble (Basalt / Slate Pebble) in the encyclopedia →

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Physical properties

Formation & geological history

Formed through mechanical weathering and erosion. Pre-existing dark rocks such as basalt, shale, slate, or dark limestone are broken down and smoothed by river or ocean wave action over years.

Uses & applications

Used in landscape gardening, aquariums, pebble mosaic art, decorative stone arrangements, and massage stones (basalt pebbles).

Geological facts

Black pebbles often get their dark coloration from fine iron-magnesium rich minerals (like in basalt) or organic carbonaceous material (like in black shale/slate). Smooth water-worn pebbles can travel hundreds of miles down river systems before reaching beaches.

Field identification & locations

Identify by its smooth, water-abraded surface and dark grey-to-black color. Found along sea beaches, riverbeds, and gravel pits worldwide. Easy to collect for craft and garden projects.

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