GL101 Lecture Notes - Lecture 7: Intrusive Rock, Viscosity, Orthoclase
Document Summary
Granite a coarse-grained rock composed predominantly of feldspar and quartz, is an intrusive rock. Igneous rocks indicating that they were deeply buried. Obsidian volcanic glass and is not composed of minerals. Chill zones in the intrusive rock adjacent to contacts with country rock. Texture refers to a rock"s appearance with respect to the size, shape, and. Crystalline rocks are made up of interlocking crystals. Glassy rocks composed primarily of glass and contain few, if any, crystals. Fragmental rocks composed of fragments of igneous material. Both tuffs and volcanic breccias have fragmental textures. <2mm, in volcanic breccias, the fragments are >2mm. A vesicular texture shows a series of cavities formed by bubbles of gas trapped in a lava when it solidified. Pumice is a frothy glass formed from viscous lava; scoria is a highly vesicular basalt. kilometers. Characteristically, these rocks are coarse-grained, reflecting the slow cooling and solidification of magma. be seen easily with the naked eye, coarse-grained.
