Igneous Rocks
(Volcanic Rocks) Large temperature change = rapid cooling, which leads to...
very tiny crystals
(extrusive) form at the surface of the Earth
volcanic igneous rock
Mafic igneous intrusive rock examples
basalt and gabbro
__________ indicates the temperatures at which minerals melt or crystallize.
bowen's reaction series
Felsic igneous intrusive rock example
granite
Magma or lava cools to form ______ rock.
igneous
Mafic rocks are higher in _________ and __________
iron and magnesium
(Plutonic Rocks) Small temperature change = slower cooling, leading to...
large, visible mineral grains
Felsic igneous rocks are usually...
light colored and rich in silica
Basalt is mafic or felsic?
mafic
Olivine and pyroxene are _________ minerals.
mafic
Which rock is lower in silica? (mafic or felsic rock?)
mafic
describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color
mafic
Rich in calcium, iron, and magnesium, and poor in silicon
mafic rocks
Although both types of rock cool from magma, the composition of _________ rocks is higher in iron and magnesium, while __________ rocks are higher in aluminum, sodium, and silica.
mafic; felsic
Different ______ have different composition and contain whatever elements and gases were in the rock or rocks that melted.
magmas
Mafic rocks are higher in ____ and ______.
magnesium; iron
TRUEORFALSE: Assuming suitable composition, quartz is the last mineral to be crystallized from magma.
true
TRUEORFALSE: Increased pressure raises the melting temperature of rock.
true
TRUEORFALSE: Olivine crystallizes at a much higher temperature than quartz.
true
TRUEORFALSE: The rock beneath the Earth's surface is sometimes heated to high enough temperatures that it melts to create magma.
true
TRUEORFALSE: The same parent rock can produce magmas of different composition if the melting temperature is different.
true
Granite is mafic or felsic?
felsic
The Sierra Nevada Mountains are made from
felsic igneous intrusive rock
The temperature range of most magmas is _____.
700-1300 degrees celcius
Fractional crystallization occurs when
Magma temperature cools enough that only some minerals crystallize
Granite containing quartz, muscovite, potassium feldspar, biotite mica and sodium-rich plagioclase feldspar is exposed to rising temperature. What happens?
Quartz melts first, then muscovite, and potassium feldspar. As temperature continues to rise, biotite and plagioclase melt
Felsic type of igneous rock
Rhyolite
High in aluminum and sodium, and rich in silica
felsic rocks
As a rock is heated, in what order do the minerals melt?
The first ones to melt are the last ones that formed as the magma cooled
The last mineral to melt from a rock is:
also the first one to crystallize
The first mineral to melt from a rock is:
also the last one to crystallize
Felsic rocks are rich in ___________ and ___________
aluminum and sodium
What temperature allows olivine and Ca-rich plagioclase to crystallize from magma?
around 1400 degrees centigrade
Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.
felsic
Igneous rocks are classified by
composition and texture
Mafic igneous rocks are
dark and poor in silica
Intermediate igneous rocks contain...
equal parts of light and dark minerals
Mafic igneous intrusive rock
erupt on the surface, and cool quickly to form small crystals
TRUEORFALSE: All minerals melt at the same temperature.
false
TRUEORFALSE: Extrusive igneous rocks form from magma that cools and solidifies within the Earth's crust.
false
TRUEORFALSE: Helium is the most abundant element present in magma.
false
TRUEORFALSE: Igneous rock that melts at the highest temperatures becomes granitic.
false
TRUEORFALSE: In the Earth's crust temperature decreases with depth.
false
TRUEORFALSE: Marble is an igneous rock.
false
intrusive form below Earth's surface
plutonic igneous rock
The same type of magma can produce either ___________ or ______________ rock.
plutonic; volcanic
Whereas dark-colored rocks are...
poor in silica
Felsic igneous intrusive rock
rocks that have crystallized at a depth, with visible minerals
Light-colored rocks are mostly composed of...
silica-rich minerals
Felsic rocks typically contain ____ and _____.
sodium; aluminum
The rate the magma cools determines the ______ of the rock.
texture
Scientists can use textures and colors of rocks to determine...
the history of their location
