SCI 102 Study Guide - Final Guide: Nevado Del Ruiz, Hawaiian Islands, Divergent Boundary
14 Dec 2016
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Document Summary
Intrusive magmas and rocks: magma that crystallizes at depth forms plutonic or intrusive igneous rocks. These rocks are observed at the surface following periods of uplifting and erosion of overlying rocks. Extrusive magmas and rocks: the solidification of lava or volcanic debris forms volcanic or extrusive igneous rocks. Granitic/rhyolitic (felsic): light-colored silicates, composed almost entirely of quartz and potassium feldspar, termed felsic (feldspar or silica) in composition, high silica (sio2) content, contain about 10% dark silicate minerals, major constituent of continental crust. Glassy: composed of unordered atoms and resembles dark manufactured glass (obsidian is a natural glass that usually forms when highly silica-rich magmas solidify) Vessicular: extrusive rock containing voids left by gas bubbles that escape as lava solidifies (pumice is a frothy volcanic glass that displays a vesicular texture) Aphanitic: fine-grained texture, composed of crystals that are too small for the individual minerals to be identified without a microscope.
