Rock Values of rocks Solid mixture of crystal of one or more minerals Human uses –Tools –Buildings –concrete Scientists –Earth & Space history –Fossil records

Composition Texture The “ingredients” of a rock (what it is made of) Determined by the sizes, shapes & positions of the grains of which it is made

Rock Origins Rocks are classified by the way they formed. Classifying Rocks

Igneous Rock Origins Rock that forms when lava cools –Time it takes to cool & solidify –Changes the rock MAGMA Solidifies like water freezing –Temperature range 700  C  C –3 ways to change magma Temperature Pressure Composition

Igneous Rocks Igneous Rock Origins and Textures The texture of igneous rock varies according to its origin.

Igneous Rock Formation Intrusive Igneous Rock Two types – inside and outside the earth When magma cools beneath the Earth’s surface. Usually coarse texture Cools slowly Named for size and way they intrude –Plutons (balloon shape formations) –Batholiths –Sills

Extrusive Igneous Rock Igneous rock that forms on the Earth’s surface Forms quickly Very small crystals or none at all i.e. lava flow becomes extrusive igneous rock