igneous

Basalt Pebble

Basalt (Mafic volcanic rock)

Hardness: 6.0 on Mohs scale; Color: Black, dark gray, or dark green; Luster: Dull to waxy; Texture: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0.

Hardness: 6
Color: Black, dark gray, or dark green
Luster: Dull to waxy

Identified March 30, 2026More igneous →

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Physical properties

Hardness: 6.0 on Mohs scale; Color: Black, dark gray, or dark green; Luster: Dull to waxy; Texture: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0.

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. This specimen appears water-worn, indicating it was shaped by fluvial or coastal transport.

Uses & applications

Commonly used in construction (rolled aggregates), for hot stone massage therapy, and as decorative landscaping stones.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.

Field identification & locations

Identify by its dark color, heavy weight for its size, and absence of visible large crystals. Commonly found on beaches or in riverbeds near volcanic regions.

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous