igneous

Basalt with vesicles

Vesicular Basalt

Hardness: 6; Color: Dark grey to reddish-brown (weathered); Luster: Dull; Crystal structure: Aphanitic (fine-grained) with visible pores (vesicles); Specific gravity: 2.8-3.0.

Hardness: 6
Color: Dark grey to reddish-brown (weathered)
Luster: Dull

Identified April 7, 2026More igneous →

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Physical properties

Hardness: 6; Color: Dark grey to reddish-brown (weathered); Luster: Dull; Crystal structure: Aphanitic (fine-grained) with visible pores (vesicles); Specific gravity: 2.8-3.0.

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava at the surface. Vesicles formed by trapped gas bubbles during solidification. Common in volcanic regions and oceanic crust.

Uses & applications

Used in construction, as road base, in concrete aggregate, and sometimes in landscaping or as a medium for aquarium filtration.

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 on the Moon and Mars.

Field identification & locations

Identify by its dark color, heavy weight for its size, and the presence of small holes (vesicles). Commonly found on beaches near volcanic coastlines or in glacial till.

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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