Basalt with Epidote Veins

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Dark grey to black with light green veins; Luster: Dull to sub-vitreous; Structure: Aphanitic (fine-grained) with secondary vein filling; Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. The green veins are likely epidote or chlorite formed through hydrothermal alteration during low-grade metamorphism.

Uses & Applications

Used in construction as crushed stone, high-quality road base, and concrete aggregate. Specifically attractive pieces are used as aquarium stones or river rock decor.

Geological Facts

Basalt is the most common rock type on the Earth's surface and makes 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 heavy weight (high density), dark color, and fine grain. The green mineral veins are a classic sign of hydrothermal activity. Commonly found in volcanic regions and oceanic crust outcrops.

Identified on: 4/30/2026

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