1. Rock Composition and Types

2. How could you tell how many different types of rocks are in the photo
How could you tell how many different types of rocks are in the photo? What characteristics would you look for?

3. What are Rocks? Rocks are: naturally formed non-living Earth material
Rocks are made of collections of mineral grains and/or remains of living things held together in a firm solid mass.

4. How is a Rock Different from a Mineral?
Rocks are made of minerals
mineral grains can be microscopic to larger than your finger

5. Identifying Rocks Rocks are identified by:
1.Composistion: minerals they contain- each type has some unique minerals
2.Texture: grain size is an important characteristic in all three types

6. Sample Materials
Texture
Formation
Rock Type
Left Rock
plagioclase, hornblende, pyroxene
crystals visible to naked eye
magma cooled slowly
diorite
Right Rock
one type of crystal visible, rest microscopic
magma erupted and cooled quickly
andesite

7. Three Types of Rocks
Igneous
Sedimentary
Metamorphic

8. Igneous rocks
All igneous rocks are the result of cooled magma or lava!
Where the rock cools determines its appearance.
Intrusive- cooled inside Earth’s crust
Extrusive- cooled outside Earth’s crust

9. Igneous Rock Characteristics
-spots or speckles
-heavy or light
-holes or solid
-Colorful
-smooth and glassy or rough and gritty

10. Why does it look like that
composition of the minerals in the magma or lava
how fast the magma or lava cools
slower cooling = larger crystals
faster cooling = smaller crystals

11. Igneous Rock Characteristics
Intrusive= Slow cooling
Form inside crust
Coarse texture
Larger, visible crystals
Heavier
No holes
Light or dark colored depending on silica content
Extrusive= Rapid cooling
Form outside crust
Fine texture
Small or no crystals
Very light
May have holes
Light or dark colored depending on silica content (high silica is lighter)

12. Sedimentary Rocks
Formed by weathered sediments and dissolved minerals deposited into an area over time
Compacted into layers over time
Water can help cement sediments together

13. Sedimentary Rock Characteristics
Gritty, grainy, sandy texture
Made of sediment
Rough or smooth depending on size of sediment
Rock chuncks
Fossils
Layers
Not shiney
Earthy colors

14. Sedimentary Rock Formation
Clastic sedimentary rocks- composed of fragments and particles derived from pre-existing rock- sandstone, conglomerate
Chemical sedimentary rocks- dissolved minerals carried to lakes and seas in rivers or ground water precipitates to form chemical sediments like salt or limestone
Organic sedimentary rock- made of living matter accumulated and compacted over time- coal, coquina

15. Transport & Deposition
Sediments are transported by water, wind, ice or gravity
Sediments will settle out of water when water slows.
Sedimentary rocks form in layers with the youngest on the top

17. Sedimentary Rocks Reflect their Environment
Beaches & deserts deposit sand
Sediments from the bottoms of ponds, lakes, marshes, & swamps usually will be smaller and well sorted.
Glaciers deposit sediment without sorting.

18. Metamorphic Rock Characteristics
-sparkly
-smooth
-wavy or swirly layers
-colorful
-heavy
-hard
-solid
-waxy

19. Metamorphic Rock Formation
Heat and/or pressure change an existing rock into a metamorphic rock
Change can be physical, chemical, or both
Foliation can occur if the rock forms layers. Metamorphic rocks are either foliated or non-foliated.

20. Foliation

21. Metamorphic Diversity
Metamorphic rocks are very diverse because there are some many different parent rocks that can be metamorphosed to various degrees.