Basalt (with possible Olivine inclusions)

Physical Properties

Hardness: 6.0–7.0 on Mohs scale. Color: Dark gray to black, often weathering to brown. Luster: Dull to earthy. Crystal structure: Aphanitic (fine-grained), sometimes porphyritic. 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 of a terrestrial planet or a moon. Most common rock in Earth's crust, found in oceanic plates and volcanic hotspots.

Uses & Applications

Used primarily in construction for aggregate, road base, railroad ballast, and high-quality concrete. Also used for stone wool insulation and occasionally for decorative garden stones.

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 found on the Moon, Mars, and Venus.

Field Identification & Locations

Identify by its dark color, heavy weight (density), and fine-grained texture. Found near volcanic regions, rift valleys, and oceanic ridges. Often shows small green crystals if olivine is present.

Identified on: 5/8/2026

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