1. Rocks

2. What is a rock? Which of the following are rocks: Ice Water Coal
Dead Plant
Table Salt
Processed Sugar
Mined Diamond
Artificial Diamond

3. Definition Solid Naturally occurring Combinations (mixtures!)
Minerals and/or organic materials

4. List Rocks Not Rocks Ice Water Coal Dead Plant Salt Sugar
Mined diamonds Artificial Diamonds

5. How are igneous rocks formed?
Are made from magma that has been cooled down from liquid to solid

6. Difference between magma and lava?

7. Answer Magma is molten rock inside the Earth
Lava is molten rock on the surface of the Earth

8. Rock Characteristics Use to tell history, origin of the rock
Did it form inside or on the surface of Earth
How long did it take to form?

9. Rock Characteristics
Rock Texture: Relates to size of the mineral crystals. The size of the crystal indicates the amount of time it takes to cool down and form a solid object. The larger the crystals, the longer the time of formation
Types of textures-
Coarse Grained: Large crystals
Fine Grained : Small crystals. Will usually not be able to see crystals without microscope

10. Other texture types Glassy: No crystals, even under a microscope
Indicates very rapid cooling of lava (seconds)
Vesicular: Rocks with holes
Holes indicate escape of gases during rapid cooling

11. Color (2nd Characteristic)
Color indicates composition of the rock
Light colored rocks: indicate rocks with high concentrations of Si, O, K and Na
White, pinks and gray
These rocks have a Felsic composition
Formed within continents

12. Color Dark colored: Color dominated by dark greens and black
These rocks have high concentrations or Fe, Mg and Ca
These rocks have a mafic composition
These rocks are formed within oceans

13. Nothing is black or white…
A lot of rocks are combinations of felsic and mafic materials
Color will be medium dark (usually dark gray)
These have an intermediate composition

14. Felsic Rocks

15. Mafic Rocks

16. Density (3rd Characteristic)
Mafic rocks are generally more dense than Felsic rocks

17. Rock Names
Match the name to your rock sample based on your observations
Basalt- fine grained , mafic
Gabbro- coarse grained, mafic
Granite- coarse grained, felsic
Obsidian- glassy, mafic
Pumice- vesicular (very small holes), felsic
Tuff- fine grained, felsic
Scoria – vesicular (larger holes), mafic

18. Types of volcanic rocks
Obsidian: Mafic, Glass, no crystals, instant solid
Tuff, pumice: Felsic, Tiny crystals, with holes, quick solidification
Basalt: Mafic, tiny crystals, lava solidification
Granite, Felsic, large crystals, magma solidification without exposure to air

19. What do the rocks tell about its history…
Basalt, obsidian, pumice, tuff and scoria are examples of extrusive igneous rocks.
These rocks were created from the material extruded from an volcanic eruption
In general, extrusive rocks have no crystals or very small crystals: short cooling time

20. Gabbro,and granite are examples of intrusive igneous rocks
Formed when magma slowing cools inside the earth before exposed through erosion
Formed when magma is given a chance to slowly cool over millions of years, without being exposed to the surface of the earth

21. Why do intrusive rocks grow such big crystals?
Because the rocks in the interior of the Earth are poor conductors of heat, it takes a long time for the hot magma to be cooled. Thus, the intrusive igneous rocks have a coarse-grained texture due to their slow cooling.

22. Devils tower