1. Classifying Rocks

2. Geologists classify rocks by their:
Composition
Color/shape
Texture

3. Geologists observe composition
What minerals does the rock contain?
There are 20 minerals that make up the Earth’s crust and forms rock

4. Geologists observe
Color and shape of crystals in a rock to identify the minerals in the rock

5. Geologists observe Texture
*texture is how something looks and feels

6. Textures can include grains
*particles of minerals and other rocks
*give rocks their texture
*3 Grain sizes
*coarse, fine, no visible sign
*2 Grain shapes
*rounded, jagged
*2 Grain patterns
*non-banded and banded