RLNI+5.2

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Vocabulary

 * Extrusive Rocks**: igneous rock formed from lava that erupted onto earth's surface
 * Intrusive Rocks**: igneous rock formed when magma hardened beneath earth's surface
 * Porphyritic Texture**:large crystals are scattered on a background of much smaller crystals

Outline

 * Characteristics of igneous rocks
 * classified according to:
 * origin
 * texture
 * mineral composition
 * origin
 * extrusive rock
 * formed by lava that erupted onto earth's surface
 * basalt is most common
 * intrusive rock
 * formed when magma hardened beneath earth's surface
 * granite is most common
 * texture
 * can be:
 * fine grained
 * coarse grained
 * glassy
 * porphyritic
 * fast cooling lava forms fine grained igneous rocks with small crystals
 * slow cooling magma forms coarse grained rocks with large crystals
 * intrusive and extrusive rocks usually have different textures
 * intrusive rocks have larger crystals than extrusive rocks
 * mineral composition
 * Uses of igneous rocks
 * tools and building materials
 * basalt is crushed to make graval