Classifying Rocks CH 3 Prentice Hall p CH 3 Prentice Hall p

Are made of mixtures of minerals and other materials. – Granite Quartz Feldspar, Mica Hornblende Rocks

Characteristics (brainstorm) Group DGroup EGroup F DensityHardnessPorous Group AGroup BGroup C Rock Color TextureLuster

Texture: size, shape and pattern of rock grains. Grains: particles of minerals or other rocks. Texture

Coarse Grained- Large and easy to see. Fine Grained- small. Texture (Grain Size)

Grains vary widely. – Tiny particles of sand – Look like seeds – Crystals – Smooth / rounded – Jagged Texture (Grain Shape)

Grains often form patterns. – Some lie in flat layers. – Rows of grains. – Random grains. Texture (Grain Pattern)

Why? Have no grain. Why? – Cool very quickly when they form, giving the rock a smooth, shiny texture like thick glass. Texture (No Visible Grain) Obsidian

3 Groups- refers to how the rocks formed. Igneous Forms from cooling molten rock. Magma- below the surface. Lava- above the surface. Sedimentary Forms from particles of other rocks, remains of plants and animals that are pressed and cemented together. Metamorphic Forms from pre-existing rock, deep underground. Changes rock with heat, pressure and chemical reactions. Origin

Use a microscope to look at the size & shape of crystals to ID (identify) minerals in the rock. Acid test - tests for carbonates Magnetic Test - tests for iron and nickel Mineral Composition

Rock Cycle