Minerals and Rocks

What is the difference?

• Minerals: nonliving structures with set chemical formulas

• Example: SiO2 is quartz

• Rocks: made of combinations of minerals

Pair share:Pair share:

A: Tell B an A: Tell B an analogy… a analogy… a mineral is to mineral is to a rock as a a rock as a _______ is _______ is to a ______.to a ______.

How rocks are classified

Rocks are organized into groups in two ways:

1) By the minerals they are composed of

2) How they are formed

Igneous rocks• Formed when molten rock cools

(volcanic)

• Extrusive cools at the surface– Example: obsidian

• Intrusive cools underground forming crystals• example: granite

Pair share:Pair share: B tell A a what “ Ex” in “In” mean B tell A a what “ Ex” in “In” mean and how that relates to where these 2 types of and how that relates to where these 2 types of rock cool.rock cool.

Sedimentary rocks

• Form from fragments of older rocks• Layers can be compressed• Minerals in water can seep through and

“cement” them together

Whiteboard: Whiteboard: Why do you Why do you think that think that fossils are fossils are only found in only found in this type of this type of rock?rock?

Metamorphic rocks• Heated and put under pressure deep in the crust

• Undergo chemical changes

Examples:

limestone becomes marble shale becomes slate

Pair share:Pair share: A: tell B what A: tell B what other things go other things go through through metamorphosis metamorphosis and why you and why you think this kind think this kind of rock has that of rock has that name.name.

Rock cycle: takes millions of years

Over time rocks are:

•heated and melted

•Cooled

•Compressed

•Undergo chemical changes

•Exposed to wind & H20

Pair sharePair share: B tell A what : B tell A what igneous rock must go igneous rock must go through to become through to become sediment and what sediment and what metamorphic rock must go metamorphic rock must go through to become through to become magma. magma.

Superposition oldest rocks are in the lowest layers

(relative dating)

Radioactive dating

is a measure of the decay of isotopes

Isotopes decay at a known rate

- can calculate age using R=Δ/T

Absolute dating

White board: What is an isotope?

White Board Review 1) What is the difference

between minerals & rocks?

2) What are the two ways rocks are classified?

3) How is the absolute age of a rock determined?

Summary

• Main idea• Key concepts• Important facts• How the facts relate to the main idea