GENERAL GEOLOGY

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: -Magmas that erupt as lava onto the earth’s surface cool and solidify rapidly. Rapid cooling results in an aphanitic igneous texture, in which few or none of the individual minerals are big enough to see with the naked eye. This is sometimes referred to as a fine-grained igneous texture.

Detailed explanation-3: -Lava flow in Hawaii Lava cools quickly on the surface of the earth and forms tiny microscopic crystals. These are known as fine-grained extrusive, or volcanic, igneous rocks. Extrusive rocks are often vesicular, filled with holes from escaping gas bubbles. Volcanism is the process in which lava is erupted.

Detailed explanation-4: -Obsidian is produced when lava cools very quickly. The lava cools so quickly that no crystals can form.

Detailed explanation-5: -On the other hand, lavas cool quickly at the earth’s surface and are characterized by fine-grained texture, in which the crystals are too small to be seen by the unaided eye. Very quickly cooled lavas, typically those quenched in water, will have a glassy texture. They cool too quickly to form crystals.