Classifying+Igneous

**Classi** **fying Igneous Rocks** By: Prarthana Venkatesh and Yuki Yamammoto 7A 

Igneous rocks are intrusive or extrusive, it all depends on HOW they are formed. The magma from which they form is also use d to classify igneous rocks. The type of magma that cools to form an igneous rock determines some properties of that rock, like the [|mineral] composition, density, color and [|melting temperature]. ** Bas ****al ****tic **** Rocks ** Basaltic igneous rocks form from magma that is rich in iron and magnesium, and poor in silica. The iron and magnesium give i t the dark color. They are dense, and dark colored. [|Basaltic] lava is fluid, and flows freely from volcanoes, especially in Hawaii. Basalt forms on the surface of the Earth, it is an extrusive rock. **Granite** **Rocks** <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 130%;"><span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">Granite Igneous rocks form from magma that is thick, stiff and contains lots of [|silica], less of iron and magnesium. They are light colored, and have a lower density than basaltic rocks. Because granitic magma is stiff, it can build up a lot of gas pressure, which is released explosively, in volcanic eruptions. Granite forms from [|magma], below the Earths surface. <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 132%;">The mineral compositions of [|Andesitic] Rocks are between basaltic and granite. Many volcanoes around the Pacific Ocean are made up of Andesitic Rocks. These volcanoes can erupt violently, like volcanoes that erupt granitic magma.
 * ~ [[image:Basaltic_Rock.upload.prarthana.jpg width="145" height="113" caption="Basalt"]][[image:gabbro.upload.prarthana.jpg width="145" height="116" align="right" caption="Gabbro"]] ||~ [[image:scoria.upload.prarthana.jpg width="144" height="112" caption="Scoria"]] ||
 * ~ [[image:obsidian.upload.prarthana.jpg width="145" height="124" caption="Obsidian"]] ||~ [[image:Granite_Rock_.upload.prarthana.jpg width="132" height="122" caption="Granite"]] ||~ [[image:rhyolite.uploaed.prarthana.jpg width="132" height="123" caption="Rhyolite"]] ||~ [[image:pumice.upload.prarthana.jpg width="131" height="126" caption="Pumice"]] ||
 * <span style="font-family: 'Comic Sans MS',cursive; font-size: 187.2%;">Andesi ****<span style="font-family: 'Comic Sans MS',cursive; font-size: 187.2%;">tic ****<span style="font-family: 'Comic Sans MS',cursive; font-size: 187.2%;">Rocks **
 * ~ [[image:diorite.upload.prarthana.jpg width="161" height="121" caption="Diorite"]] ||~ [[image:Andestic_Rock.upload.prarthana.jpg width="160" height="122" caption="Andesite"]] ||

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 150%;">Igneous Rocks Rock Cycle
 * <span style="font-family: 'Comic Sans MS',cursive; font-size: 190%;">Links to Related Pages **

<span style="font-family: 'Comic Sans MS',cursive; font-size: 130%;">** Bibliography ** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;"> //**Information:**// [|http://library.thinkquest.org/J002289/][|igneous.h][|tml] [] [] [|http://www.tulane.edu/~sanelson/geol111/igneous.htm] [] [|http://www.abheritage.ca/abnature/geological/ph][|otos/class_igneous_rock][|s.GIF] [] //**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Pictures: **//<span style="font-family: Arial,Helvetica,sans-serif;"> [|http://upload.wikimedia.org/wikipedia/commons/archive/18/20080122084456!Scoria_Macro_Digon3.jpg] [|http://geology.com/rocks/pictures/gabbro.jpg] [] [] [|http://www.swisseduc.ch/stromboli/glossary/icons/pumice_2.jpg] [] //**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;"> Books: **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Glencoe Earth Science Textbook //