igneous rocks Flashcards
what is an intrusive igneous rock
formed when magma hardens below the surface
what is an extrusive igneous rock
lava hardens above the surface
cooling at the surface is ______ making the rock ______ in size
faster, smaller
how are igneous rocks classified
composition and texture
what is composition
what the rocks are made of or the amounts of light and dark minerals in the rock
what is texture
how rocks look like
what 4 types of textures are there
coarse-grained
fine-grained
glassy
porphyritic
define coarse grained texture
slow cooling causing larger crystals
define fine grained texture
rapid cooling resulting in smaller crystals
define glassy texture
really fast cooling
define porphyritic texture
mix of large and small crystals
what are rocks with a felsic composition
rocks composed of light colored minerals
what are rocks with intermediate composition
rocks between light and dark materials
what are rocks with a mafic composition
mostly dark-colored silicate minerals and plagioclase feldspar
what are rocks with a ultramafic compostition
made mostly of iron and magnesium-rich minerals
how can silica change depending on the type of rock
more silica more thicker magma (also more explosive)
which type of composition of a rock has the least amount of silica
mafic/ultramafic
which type of composition of a rock has the most amount of silica
felsic
what is pluton
mass of rock that forms when magma cools inside earth
what is batholith
large pluton that is mainly in the center of mountain ranges, can be exposed by uplift and erosion
what is laccolith
magma is stiff and bulges to form a dome
what is dike
sheet of igneous rock that cuts across rock layers through cracks
what is sill
sheet of igneous rock that is forced between rock layers
