igneous
Basalt Pebble
Basalt (Aphanitic Mafic Igneous Rock)
Hardness: 6 (Mohs scale). Color: Dark gray to black. Luster: Dull, earthy, or sub-metallic. Texture: Aphanitic (fine-grained), smoothed and rounded by water abrasion. Composition: Rich in plagioclase feldspar, pyroxene, and olivine.
- Hardness
- 6 (Mohs scale)
- Color
- Dark gray to black
- Luster
- Dull, earthy, or sub-metallic
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Physical properties
Hardness: 6 (Mohs scale). Color: Dark gray to black. Luster: Dull, earthy, or sub-metallic. Texture: Aphanitic (fine-grained), smoothed and rounded by water abrasion. Composition: Rich in plagioclase feldspar, pyroxene, and olivine.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava at or very near the Earth's surface. These specific pebbles were subsequently shaped and smoothed over time by stream, river, or ocean wave action.
Uses & applications
Commonly used as decorative river rock in landscaping, aquariums, hot stone massage therapy, and general mineral collection specimens.
Geological facts
Basalt is the most common rock type in the Earth's crust, forming almost all oceanic crust as well as major volcanic flood basalt provinces worldwide. It is also the primary constituent of the lunar maria on the Moon.
Field identification & locations
Identified by its fine grain size, heavy density relative to size, dark black/gray coloration, and absence of visible large quartz crystals. Commonly found along riverbeds, beaches, and volcanic regions.
