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