Vesicular Basalt

Physical Properties

Hardness: 5-6 Mohs. Color: Dark gray, black, or dark green (often weathered to brownish-gray). Luster: Dull or earthy. Structure: Fine-grained (aphanitic) with many small cavities (vesicles). Specific Gravity: 2.8-3.0.

Formation & Geological History

Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface. Gas bubbles trapped in the cooling lava create the characteristic holes or vesicles.

Uses & Applications

Used as aggregate in construction, road base, drainage stone, and occasionally in landscaping/rockeries. Crushed basalt is also used in railroad ballast.

Geological Facts

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

Field Identification & Locations

Identify by its dark color, heavy weight, and the presence of small holes or voids. Commonly found in volcanic regions, near lava flows, or as glacialবরাদ্দ stones in riverbeds.

Identified on: 4/27/2026

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