1. How Geologists Classify Rocks

2. Geologist classify according to TEXTURE
Texture is the look and feel of a rock’s surface.
Texture can be described as
fine grained – with small particles
Coarse grained – with large particles
Glassy – no visible grain

3. Geologists classify according to Origin
Igneous – forms from cooled magma or lava
Sedimentary –forms from particles of other rocks or the remains of plants and animals that have compacted and cemented.
Metamorphic – forms from rock that has been changed due to heat and pressure deep below earth’s crust.

4. IGNEOUS
Igneous – forms from cooled magma or lava

5. Sedimentary
forms from particles of other rocks or the remains of plants and animals that have compacted and cemented.

6. Metamorphic
– forms from rock that has been changed due to heat and pressure deep below earth’s crust.

7. Geologists classify rocks according to Mineral composition
Microscopes can be used to see crystal shape and structure
Acid test can be used to test for carbonates
Magnet test can be used to test for iron or nickel