Rock ClassificationIgneous, Metamorphic and Sedimentary

Igneous Rocks

•The word Igneous comes from the Latin word ignis which means fire

•Igneous rocks come from magma

Magma formation

• There are three different ways that magma can form

• A change in

• Temperature

• Pressure

• Composition

A change in temperature

•When the temperature of an area rises it can cause a rock to melt into magma

A change in pressure

• If a rock heats up and rises pressure is released allowing the rock to melt into a liquid

• This is what happens when a rock rises from the center of the Earth moves closer to the crust

• **Remember the inner core is solid because of all the pressure

A change in composition

• If a fluid is combined with a rock it may lower the rocks melting point . Then the rock melts into magma

• We lower the boiling point of water when we add salt to it for Mac n Cheese

Felsic vs Mafic rocks

• Felsic rocks are light colored and have a lower density

• Mafic rocks are darker colored and have a higher density

Coarse grained vs Fine Grained

• Coarse grained rocks are formed when magma cools over long periods of time. The crystals have more time to grow

• Fine grained rocks cool quickly and the crystals don’t have a long time to grow

Intrusive Igneous Rocks

• Formed inside the crust of the Earth

• Usually coarse grained because the crust insulates the rock and allows it to cool slowly

Extrusive Igneous Rocks

• Rocks that form when magma erupts onto the Earth’s surface

• These rocks usually have fine or no crystals because the lava cools quickly