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

How rocks are classified Rocks are organized into groups in two ways: 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: B tell A a what “ Ex” in “In” mean and how that relates to where these 2 types of rock cool.

Sedimentary rocks Form from fragments of older rocks Whiteboard: Why do you think that fossils are only found in this type of rock? Form from fragments of older rocks Layers can be compressed Minerals in water can seep through and “cement” them together

Metamorphic rocks Heated and put under pressure deep in the crust Undergo chemical changes Examples: limestone becomes marble shale becomes slate Pair share: A: tell B what other things go through metamorphosis and why you think this kind of rock has that name.

Rock cycle: takes millions of years Over time rocks are: heated and melted Cooled Compressed Undergo chemical changes Exposed to wind & H20 Pair share: B tell A what igneous rock must go through to become sediment and what metamorphic rock must go through to become magma.

Superposition oldest rocks are in the lowest layers (relative dating)

Absolute dating Radioactive dating is a measure of the decay of isotopes Isotopes decay at a known rate - can calculate age using R=Δ/T 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