2. Rocks are classified by how they formed and what they’re made of There are 3 general classes of rocks: –Igneous –Sedimentary –Metamorphic

3. Are formed when lava and magma cool to form solid rock

4. Extrusive: are formed once magma reaches the surface (lava) and cools –Ex: basalt, pumice Intrusive: are formed from magma that cools and solidifies within the crust, which may later be uncovered by the process of erosion –Ex: granite gabbro

5. Are formed when sediments (sand clay, and silt) are compressed and become solid rock

6. Formed by wind, water, snow or organisms breaking down other rocks into sediments Most sediments are deposited on the bottom of lakes, rivers and seas, and then compressed to form rock. Cover about 75% of Earth’s surface Many sedimentary rocks have been moved by water, wind, waves, currents, ice or gravity.

7. sandstone limestone chalk shale Halite (rock salt) coal Common examples

8. Metamorphic rocks form when existing rocks are heated or squeezed; they recrystallize and might change chemically.

9. All kinds of rocks can be changed Can change the crystal structure, texture, or can form new minerals gneiss marble limestone granite

10. In the rock cycle, rocks change from one type to another over millions of years. A rock in any part of the cycle could become any other kind of rock.

12. Igneous Rocks Sedimentary Rocks Metamorphic Rocks Sediments Magma Heat and Pressure Melting Cooling and Hardening Weathering and Erosion cementation

14. A mineral is an inorganic solid material with a particular chemical makeup and orderly arrangement of atoms.

15. Rocks are usually composed of two or more minerals. Minerals form from hardening of magma or lava Mineral formation clues include size and how mineral crystals fit together. Solid materials with a repeating pattern of atoms are called crystals.

16. Cleavage- splitting into thin sheets Fracture- breaking into rough edges Color- many different colors, not mineral specific Shape (habit)- special arrangement of atoms, if grown unimpeded Luster- describes how light reflects from a mineral’s surface.

17. Streak- is the color powder produced when a mineral is scratched on an unglazed white tile. Hardness- Moh’s scale is used to classify minerals from 1 (softest, talc) to 10 (hardest, diamond). It is also a test of which minerals scratch or are scratched by others.

18. Other properties of minerals include: magnetism, double refraction, taste, or reactions with acid.

19. Rare minerals which can be cut and polished are gems. This makes them ideal for jewelry.

20. An ore contains enough useful mineral to be sold at a profit. Copper is an example of an ore.