By Madison Wacaser #26 Igneous rocks are formed by lava. The magma comes from the inside the earth. The definition of igneous rocks it rock formed by the solidification of magma. When the magma starts pushing up it erupts out of volcanoes. When it cools, depending on how the magma cools and how long it takes to cool it will form different rocks such as obsidian, granite, basalt, pumice, pegmatite, rhyolite, diorite, tuff, andesite, scoria, peridotite, and gabbro. There are two kinds of igneous rock extrusive and intrusive. Extrusive rocks form quickly since it erupts out of a volcano, lands on earth’s crust and have fine grains in them. Intrusive rock forms slowly since it doesn’t reach earth’s surface it has course grains Obsidian is sea- glass like and is usually black. It forms from extrusive rock and forms intrusive igneous rock. Scoria usually has holes and always is dark colors. It’s extrusive igneous rock. Granite is intrusive igneous rock. Made of marble, basalt, and feldspar.

By Madison Wacaser #26 4 You can use basalt for sidewalks, asphalt pavement, and road base. When it cools, depending on how the magma cools and how long it takes to cool it will form different rocks such as obsidian, granite, basalt, pumice, pegmatite, rhyolite, diorite, tuff, Andesite, scoria, peridotite, and gabbro. Diorite is intrusive igneous rock and contains a mixture of feldspar, pyroxene, hornblende and sometimes quartz. Andesite is extrusive igneous rock it is made out of minerals such as hornblende, pyroxene and biotite Diorite Andesite You can also use granite for countertops in houses.

Morris, Neil. Rocks and Minerals. New York, NY: Crabtree Publishing Company, By Madison Wacaser #