EVERYDAY SCIENCE

Detailed explanation-1: -Quick cooling means that mineral crystals don’t have much time to grow, so these rocks have a very fine-grained or even glassy texture. Hot gas bubbles are often trapped in the quenched lava, forming a bubbly, vesicular texture.

Detailed explanation-2: -Extrusive (volcanic) igneous rocks cool and crystallize rapidly on the earth’s surface and so have fine grains. Extrusive rocks frequently contain some larger, well-shaped, crystals surrounding by the fine-grained material. Igneous rocks are further classified by their chemical composition.

Detailed explanation-3: -3.2: Extrusive (volcanic) igneous rocks crystallize rapidly from lava erupted onto the surface. Individual crystals usually cannot be seen by the naked eye and require a microscope. These rocks are termed finely crystalline or aphanitic and generally crystallize from lava flows. 2.