molten rock from inside the earth

slowly cooling rocks form crystals

colorless to white

Orthoclase

Biotite - thin sheets like seaweed

splintery and hard

mostly dark minerals with a little white

"Salt and Pepper" granite

Obsidian - volcanic glass

bubbles, no crystals

more bubbles than basalt

frothy volcanic glass (floats!)

pink volcanic rock

large black and/or white crystals

categorized by size

rough, gritty sand-rock

May have layers, typically grey. Looks like mud

may have shell/plant fossils inside

made from plants, easily crumbles

large sand, up to pebble size

rocks changed under heat and pressure

metamorphic sandstone

metamorphic limestone

metamorphic form of bituminous coal

metamorphic form of shale

metamorphic form of shale

metamorphosed phyllite

metamorphic form of granite

Study, study, study!