GEOL 104 Lecture Notes - Lecture 9: Olivine, Xenolith, Stoping

• School: Queen's University
• Department: Geological Sciences and Geological Engineering
• Course: GEOL 104
• Professor: Daniel Layton- Matthews

Document Summary

Form in late stages of crystallization of granitic magmas. Common crystals of quartz, feldspar and muscovite are abnormally large. Naming igneous rocks: igneous rocks are classifies by their texture and mineral composition, various igneous textures result from different cooling histories, two rocks may have similar compositions but different textures, thus different names. Composed of about 20% quartz and about 65% or more feldspar. The term granite covers a wide range of mineral compositions. Forms when large amount of gas escape through lava to form a gray mass. Erupted as a liquid then rapidly hardened on the surface: intermediate (andesitic) rocks. May resemble rhyolite, making identification more difficult without a microscope. Composed mainly of intermediate feldspar and amphibole salt and pepper appearance: mafic (basaltic) rocks. Composed mainly of pyroxene and calcium-rich plagioclase feldspar. Composed primarily of pyroxene and calcium-rich plagioclase. Makes up a significant percentage of the oceanic crust. Primarily composed of olivine, pyroxene and calcium- rich plagioclase feldspar.