metamorphic
Beach Pebble (Gray Quartzite / Fine-Grained Metasediment)
Quartzite (SiO2-dominated rock) / Metamorphic Sandstone
Hardness: 6.5-7 on Mohs scale; Color: Mottled medium to dark gray with subtle white quartz veining; Luster: Sub-vitreous to dull, smooth water-worn surface; Texture: Fine-grained, highly compact and rounded.
- Hardness
- 6
- Color
- Mottled medium to dark gray with subtle white quartz veining
- Luster
- Sub-vitreous to dull, smooth water-worn surface
Identified More metamorphic →
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Mottled medium to dark gray with subtle white quartz veining; Luster: Sub-vitreous to dull, smooth water-worn surface; Texture: Fine-grained, highly compact and rounded.
Formation & geological history
Formed via the regional or contact metamorphism of quartz-rich sandstone under intense heat and pressure. The pebble was rounded and polished through continuous wave action in a coastal beach environment.
Uses & applications
Commonly used for landscaping, decorative stone features, aquariums, pebble art, and general landscaping aggregate.
Geological facts
Smooth beach pebbles like this undergo thousands of years of natural polishing by ocean waves, grinding against sand and other stones to achieve their rounded, ergonomic shape.
Field identification & locations
Identified by its hard, scratch-resistant surface, dark gray mottled coloration, fine-grained texture, and smooth rounded pebble shape typical of beach or river cobbles. Widely found along ocean coastlines and river beds globally.
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