igneous
Basalt (Vesicular/Weathered)
Mafic Igneous Rock (Mainly Plagioclase and Pyroxene)
Hardness: 5-6 Mohs; Color: Dark grey to charcoal with olive-green or brownish weathering; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); SG: 2.8-3.0
- Hardness
- 5-6 Mohs
- Luster
- Dull/Earthy
Identified More igneous →
Explore Basalt (Vesicular/Weathered) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 Mohs; Color: Dark grey to charcoal with olive-green or brownish weathering; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); SG: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface. This specimen shows surface oxidation and mineral leaching typical of subaerial exposure.
Uses & applications
Extensively used in construction as aggregate for concrete and asphalt, railroad ballast, and occasionally for high-end stone veneers or landscaping.
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
Look for a heavy, dark-colored, fine-grained rock. It often feels denser than average crustal rocks. Look for small holes (vesicles) or green olivine phenocrysts. Found in volcanic regions globally.
