igneous
Basalt (with possible Serpentinization)
Mafic Igneous Rock (primarily Plagioclase and Pyroxene)
Hardness: 5-6 Mohs; Color: Dark grey to greenish-black; Luster: Dull to slightly waxy/slick; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0; Texture: Dense and massive.
- Hardness
- 5-6 Mohs
- Color
- Dark grey to greenish-black
- Luster
- Dull to slightly waxy/slick
Identified More igneous →
Explore Basalt (with possible Serpentinization) 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 greenish-black; Luster: Dull to slightly waxy/slick; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0; Texture: Dense and massive.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface. The greenish tint suggests it may have undergone low-grade metamorphism or hydrothermal alteration (serpentinization).
Uses & applications
Primarily used in construction as aggregate for concrete, asphalt road base, and railroad ballast. Fine specimens are used for stone carving or as aquarium 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 and Mars.
Field identification & locations
Identify by its dark color, heavy weight (density), and fine-grained texture that lacks visible crystals to the naked eye. Often found in volcanic regions or riverbeds near ancient lava flows.
