Post on 21-Jan-2016
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