Igneous rocks form when magma or lava cools and solidifies. Magma is molten rock located below Earth's surface, while lava is magma that has reached the surface. Intrusive igneous rocks form when magma cools and crystallizes slowly below Earth's surface, resulting in large crystal sizes. Extrusive igneous rocks form when lava cools and crystallizes quickly on Earth's surface, resulting in small crystal sizes. Common intrusive and extrusive rock types are listed.

1. Igneous Rocks (with slides from “ms simmons”)

2. Magma forms igneous rocks

3. What is magma? Hot molten (melted) rocks When magma cools inside the earth, it forms igneous rocks When magma (lava)cools outside the earth, it forms igneous rocks

4. Magma and lava

5. Molten rocks Inside the earth = magma Outside the earth = lava How does magma escape to the outside? (Magma escapes to the outside through ______)

6. Volcano

7. Intrusive rocks Formed when magma cools INSIDE the earth.

8. Extrusive rocks Formed when magma (as lava) cools OUTSIDE the earth. In- Ex-

9. Cooling Intrusive vs. Extrusive rocks: which will cool faster?

10. Extrusive Rocks Formed at earth’s surface Lava’s minerals cool and harden quickly Forms tiny crystals Rhyolite Obsidian Andesite Basalt

12. Magma’s minerals cool and harden slowly

13. Forms coarse crystalsDiorite Gabbro Granite

14. Quiz As the head geologist of an expedition, you come across an unknown mineral. 1. How do you convince your colleagues that it’s indeed a mineral? (hint: how do you define a mineral?) Name 5 defining criteria of the mineral that make it a mineral. a. minerals are solid 2. Name 3 properties of the mineral that you’d test to identify the mineral.

15. Quiz What is magma? i.e. what is it made of? What is lava? i.e. how is it different from magma? Which type of rocks does lava form when it cools? Which type of rocks does magma form when it cools? Define a mineral. (name 5 criteria) a. minerals are solid