Rocks

• Rocks are made of minerals

3 Types of Rocks

Igneous Rocks

• Are formed from the cooling of melted rock

Intrusive igneous rockProduced when melted rock (magma) is cooled below Earth’s surface.• Light or dark colored• Takes millions of years to form• Rocks have large crystals from

slowly cooled magma.• Examples: Gabbro, granite

Extrusive Igneous Rock- produced when melted rock cooled

(Lava) is cooled above Earth’s surface.• Light or Dark colored• Cools quickly before large crystals can

form.• Formed by volcanoes erupting or large

cracks opening up and lava oozing out.• Usually smooth, glassy appearance • May have holes.

Extrusive Igneous Rock

• Examples: 1)Basalt, has holes and is most common 2) Obsidian cools very quickly and is glassy. 3) Rhyolite is similar to granite but has no visible crystals.

Sedimentary Rocks

• are formed from broken pieces of rock, shells, mineral grains that make up sediment and collect in layers.

• Sediment is carried by wind, ice, gravity or water and is deposited.

• It takes thousands to millions of years to form sedimentary rocks.

Detrital rocks

• made of minerals or other rocks that have been deposited in layers by water, ice, gravity or wind.

• Weight of sediment above them and other minerals dissolved in water squeeze the sediment to form rocks.

• Identified by size of grains.

Examples of Detrital Rocks

• Shale- have small grains that cannot be seen.

• Sandstone - is made of larger sand sized grains.

• Conglomerates - are made from pebbles cemented together with other sediment.

Chemical Rocks-

• form when water rich in minerals evaporates.

Organic Rocks

• from living organisms that have died, piled up and compressed over millions of years.

• Examples- coal, chalk, and limestone.

Metamorphic Rocks

• are new rocks that are formed when existing rocks are heated or squeeze under pressure.

• Metamorphic – means to change form

• Can form from igneous, sedimentary or metamorphic rocks.

Foliated rocks- • have been heated or pressurized

into visible layers or grains of minerals that are often different colors.

Examples: slate, gneiss formed from granite, phylitte, and schist.

Non- foliated rocks- • do not have distinct layers or

bands. • Examples: • quartizite formed from sandstone

after it has been heated and put under pressure.

• Marble formed from limestone, and soapstone.

Rock Cycle Animation

• http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02.cfm

The Rock Cycle

The Rock Cycle

Rock identification