Basalt (Vesicular)

Hardness of 6 on the Mohs scale, dark gray to black in color, dull luster, aphanitic (fine-grained) crystal structure with visible vesicles (gas cavities), specific gravity around 2.8-3.0.

Formed from the rapid cooling of low-viscosity, iron- and magnesium-rich lava flows at the Earth's surface. Can be found in volcanic regions, oceanic crust, and continental flood basalt provinces.

Used in construction as crushed stone, railroad ballast, aggregate in concrete, and sometimes in stonework and tile.

Vesicular basalt forms when gases dissolved in the molten magma expand as pressure decreases upon reaching the surface, leaving cavities as the lava solidifies. It is the most common rock type in the Earth's crust, underlying most ocean basins.

Easily identified by its dark, fine-grained matrix and characteristic small holes (vesicles) left by gas bubbles. Commonly found near ancient or active volcanic areas and beaches where volcanic rocks have weathered out.