In this case, the magma cooled enough to form some crystals before erupting. Once erupted, the rest of the lava cooled rapidly. ... Lavas that cool extremely rapidly may have a glassy texture. Those with many holes from gas bubbles have a vesicular texture.

How do vesicular rocks cool?

When this happens gasses dissolved in the magma are able to come out of solution, forming gas bubbles (the cavities) inside it. When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes filled with gas called vesicles.

Do vesicular rocks cool fast or slow?

Vesicular texture -- basalt scoria: This is an extrusive igneous rock that chilled very quickly, so that the bubbles (vesicles) formed by escaping gas were preserved.