• 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 OriginsRocks 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-

1250C– 3 ways to change magma

• Temperature• Pressure• Composition

Igneous Rocks

Igneous Rock Origins and TexturesThe 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