EVERYDAY SCIENCE

Detailed explanation-1: -When lava comes out of a volcano and solidifies into extrusive igneous rock, also called volcanic, the rock cools very quickly. Crystals inside solid volcanic rocks are small because they do not have much time to form until the rock cools all the way, which stops the crystal growth.

Detailed explanation-2: -Extrusive Igneous Rocks: 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.

Detailed explanation-3: -Extrusive Rocks The lava cools much faster on the surface, so the minerals either form crystals that are too small to see easily, or else it forms a volcanic glass with no crystals at all. Extrusive rocks may have a few grains that are large enough to see, but most of them will be too small to see individual minerals.

Detailed explanation-4: -FELSIC ROCKS RHYOLITE-aphanitic (small crystals) of felsic minerals with the same composition of granite.

Detailed explanation-5: -Extrusive (Volcanic) Rocks Extrusive igneous rocks are also termed volcanic rocks-named for Vulcan, the Roman god of fire. Volcanic rocks have generally smaller crystal size and usually have a very-fine-grained or glassy groundmass that formed due to rapid cooling at the time of eruption.