Vesicular Basalt (Scoria)

Physical Properties

Hardness: 5-6 (Mohs); Color: Black, dark gray, or reddish-brown; Luster: Dull to sub-metallic; Crystal Structure: Aphanitic (fine-grained) with vesicles; Cleavage: None; Specific Gravity: 2.5-3.0

Formation & Geological History

Formed through the rapid cooling of magnesium-rich and iron-rich lava. The holes (vesicles) are created by gas bubbles trapped in the magma as it solidifies at or near the Earth's surface.

Uses & Applications

Used in landscaping, road construction as aggregate, concrete production, and as abrasive polishing stones (scoria/lava rock).

Geological Facts

Basalt is the most common rock on Earth's surface, making up most of the ocean floor. It is also extremely common on the Moon and Mars.

Field Identification & Locations

Identify in the field by its dark color, heavy weight (relative to size), and characteristic holes or pits. Commonly found in volcanic fields, island arcs, and mid-ocean ridges.

Identified on: 5/7/2026

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