Vesicular Basalt with Lichen

Physical Properties

Hardness: 5-6 Mohs; Color: Dark grey to black matrix with reddish oxidation; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); Features: Vesicles (gas bubbles) often filled or weathered.

Formation & Geological History

Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. The holes (vesicles) are created by trapped gas.

Uses & Applications

Primarily used in construction as aggregate, road base, and for decorative landscaping. Smaller specimens are used for educational purposes.

Geological Facts

The reddish hue on this specimen is likely due to the oxidation of iron-rich minerals (hematite) within the basalt. The round black and grey patches on the surface are actually Crustose lichens growing on the rock, not part of the mineral structure.

Field Identification & Locations

Identify by its heavy weight, dark color, and characteristic 'pitted' or 'holy' surface. Commonly found in volcanic fields, riverbeds draining volcanic regions, and oceanic crust.

Identified on: 5/15/2026

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