Vesicular Basalt

Physical Properties

Hardness: 5-6 Mohs. Color: dark grey to black. Luster: dull to sub-metallic. Structure: vesiculated/porous (scoriaceous). Composition: primarily plagioclase feldspar and pyroxene.

Formation & Geological History

Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The small holes (vesicles) are created by gas bubbles trapped in the cooling lava.

Uses & Applications

Used in landscaping (lava rock), construction aggregate, railroad ballast, and as an abrasive in 'stone-washed' denim production.

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 extremely common on the Moon and Mars.

Field Identification & Locations

Identify by its dark color, heavy weight (high specific gravity), and the presence of small pits or vesicles. It is often found in volcanic fields or near ancient rift zones.

Identified on: 4/27/2026

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