igneous
Black Beach Pebble (Basalt / Slate)
Basalt / Metamorphic Slate pebble
Hardness: 5.5-6 (for basalt) or 2.5-4 (for slate); Color: dark charcoal black to deep gray; Luster: dull to earthy matte; Texture: smooth, river- or sea-worn rounded surface; Specific gravity: 2.7-3.0
- Hardness
- 5
- Color
- dark charcoal black to deep gray
- Luster
- dull to earthy matte
Identified More igneous →
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Physical properties
Hardness: 5.5-6 (for basalt) or 2.5-4 (for slate); Color: dark charcoal black to deep gray; Luster: dull to earthy matte; Texture: smooth, river- or sea-worn rounded surface; Specific gravity: 2.7-3.0
Formation & geological history
Formed either through the rapid cooling of basaltic lava or through low-grade regional metamorphism of shale, then rounded and smoothed by water action in rivers or ocean shorelines over long periods.
Uses & applications
Landscaping, decorative craft projects, aquarium gravel, desktop pocket stones, and stress-relief worry stones.
Geological facts
Smooth black beach pebbles are highly sought after for stone painting, zen garden aesthetics, and massage stones due to their thermal retention properties and soft, water-eroded texture.
Field identification & locations
Identified by its deep charcoal color, fine grain size, smooth rounded shape without sharp edges, and absence of visible macro-crystals. Commonly found along rocky sea coasts, riverbeds, and ocean beaches worldwide.
