Igneous Rocks Flashcards
How do we classify Rocks?
We classify rocks according to how its formed.
What is are Igneous Rocks?
An igneous rocks are rocks that form from the cooling and solidification of magma or lava.
Lava
Molten rock above surface
Magma
Molten rock under surface
How to classify Igneous Rocks?
Igneous Rocks are classified according to where they cooled and solidified.
These rocks are formed inside the earth from Magma
Intrusive Igneous Rocks
Intrusive Igneous Rocks are also called:
Plutonic Rocks
Because magma cools slowly in Intrusive Igneous Rocks:
Big Crystals Form
Any crystal larger than 1 milimeter =
Intrusive Rock
These rocks form above the surface from Lava
Extrusive Igneous Rocks
Because lava cools quickly in Extrusive Igneous Rocks:
Small or no Crystals Form
Extrusive Rocks are also called
Volcanic Rocks
Extrusive Rocks may be vesicular. What are vesicular rocks?
Vesicular Rocks are rocks with holes or cavities. (Ex. Pumice)
A type of igneous rock composition that is made mostly of light minerals such as quartz and feldspar.
Felsic (Light/ Low Density)
A type of igneous rock composition that is in between felsic and mafic.
Intermediate
A type of igneous rock composition that is made mostly of dense, dark minerals like olivine and pyroxene.
Mafic (High Density)
A type of igneous rock rock that contains more than 90% mafic minerals and have very few light, felsic minerals in them.
Ultramafic (90% Mafic)
Is Basalt considered Intrusive or Extrusive?
Basalt is an extrusive igneous rock common below the oceans, though it is also found in some places on continents.
To harden after cooling.
Solidify
What are the 4 mineral compositions of igneous rock?
Felsic, Intermediate, Mafic, Ultamafic
