igneous
Vesicular Basalt
Vesicular Basalt (Aphanitic Mafic Igneous Rock)
Hardness: 5-6 Mohs. Color: dark grey to brownish-green depending on oxidation. Luster: Dull/Earthy. Texture: Vesicular (full of holes or gas bubbles).
- Hardness
- 5-6 Mohs
- Color
- dark grey to brownish-green depending on oxidation
- Luster
- Dull/Earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 Mohs. Color: dark grey to brownish-green depending on oxidation. Luster: Dull/Earthy. Texture: Vesicular (full of holes or gas bubbles).
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The holes (vesicles) are created by trapped gas bubbles that escaped as the pressure decreased during eruption.
Uses & applications
Commonly used in construction for road base, concrete aggregate, and railroad ballast. Also used as decorative landscaping stone and in bbq grills as 'lava rocks'.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. The vesicles can sometimes be filled with secondary minerals like quartz or zeolites over millions of years, forming amygdaloidal basalt.
Field identification & locations
Identifiable by its porous, sponge-like appearance and heavy weight relative to pumice. It is commonly found near volcanic activity hotspots like Hawaii, Iceland, and the Pacific Northwest.
