PPT-Lecture 3: Igneous Textures & Rock Geometry

By David Allison Igneous Texture Texture size shape and arrangement of constituent mineral grains Crystallinity percentage of crystals versus glass depends on Rate of cooling SiO2 content of magma. Colby Geology. Igneous Rocks. Classification based on . composition. and . texture. .. COMPOSITION. Principally the rock-forming minerals. Olivine. Pyroxenes. Amphiboles. Micas. Feldspars. Quartz. Constitute 95% of minerals in . Hot rocks/Fire Rocks. Igneous Rock . Igneous rocks form . when molten rock cools and solidifies. . Molten rock is called magma when it is below the Earth’s surface and lava when it is above.. when molten rock cools and solidifies. ROCKS AND THE ROCK CYCLE. INTRUSIVE IGNEOUS ROCK. Formed under the surface of the earth. Formed from cooling magma. Cools slowly. Forms medium mineral grains. Granite is a light-colored . igneous rock. By Mr. Krall. What is a Rock?. A . rock. is a mixture of minerals.. Rocks form and reform through the . rock cycle. . . Lava/Magma. THE ROCK CYCLE. Igneous Rock. Igneous . (. ig. -nee-us) . rock. forms when molten rock cools and solidifies.. Igneous. rocks form from the solidification or crystallization of minerals in molten material.. If the rock form below the Earth’s surface it is considered . magma. Molten rock that hardens on the Earth’s surface is called . Granite, Basalt, Obsidian, Pumice and many others . Igneous Rocks are records of the thermal history of Earth. Most common of all rocks is Granite: . Granite . is a light-colored . igneous rock.  with grains large enough to be visible with the unaided eye.  It forms from the slow crystallization of magma below Earth’s surface.  Granite is composed mainly of quartz and  feldspar with minor amounts of mica, amphiboles and other minerals.   This mineral composition usually gives granite a red, pink, gray or white color with dark mineral grains visible throughout the rock. Types of Rocks. Rock: an aggregate of one or more minerals. Igneous Rocks: crystallize from a magma. Sedimentary Rocks. Clastic: formed by the erosion of pre-existing rocks. Chemical/Biochemical: precipitated from chemical reactions. 3 Types of Rocks. There are 3 different types of rocks;. Igneous. Sedimentary. Metamorphic. Igneous Rock . . Igneous rocks are formed by magma and lava as it cools. Igneous rocks form in two different ways. . 2. Major Rock Groups. Igneous. Formed from . molten rock (magma/lava) that has cooled. Literally means “from fire”. 1. Extrusive . igneous rock is formed from lava (on earth’s surface) and tends to solidify quickly. Metamorphic. Rock. What is it made up of?. Sand, clay, silt, organic matter (fossils). How is it formed (process)?. Weathering. (wind, flowing water, ice, living organisms) create sediment. Erosion. CLASSIFICATION OF ROCKS:. ON THE BASIS OF MODE OF FORMATION ROCKS ARE CLASSIFIED INTO THREE CATEGORIES:. 1 IGNEOUS ROCKS. 2 SEDIMENTARY ROCKS. 3 METAMORPHIC ROCKS.  . ROCKS. IGNEOUS ROCKS:.  . IGNEOUS ROCKS, ALSO KNOWN AS PRIMARY ROCKS ARE FORMED BY SOLIDIFICATION OF MAGMA. MAGMA IS MOLTEN ROCK MATERIAL CONSISTING OF LIQUID,GAS AND CRYSTAL.IGNEOUS ROCKS ARE RECODS OF THERMAL HISTORY OF EARTH.. Course #75T01. brights@hartwick.edu. Rocks. They’re everywhere! On the ground, in the ground… . Different sizes, different shapes, different colors, different textures…. . What exactly is a rock, and why do rocks vary so much?. . GLY 4310 - Spring, 2020. 2. Igneous Textures. Phaneritic:. Crystals are readily visible with the unaided eye.. Aphanitic:. Crystals, if present, are too small to be seen with the unaided eye.. Fragmental: . The Rock Cycle. Defined: . The process by which all rocks on Earth are formed and how basic Earth materials are recycled over time . Note: A very, very long time. The Rock Cycle. Three main types of rock on Earth.