Geology chapter 3 - 4
mafic
50% silica content
intermediate
60% silica content
felsic
70% silica content
What is required to generate an igneous rock with a fine-grained texture?
A fine-grained texture is the product of rapid cooling and crystallization of lava.
carbonates
CO32-
halides
Cl−, F−, Br−
Amphibole −
Double chain
rhyolite
Extrusive igneous rocks
Which of the following is considered a ferromagnesian silicate? CHOOSE ALL THAT APPLY.
Garnet; Biotite
What is a volatile?
Gases dissolved in a magma
Igneous rocks of felsic composition have ______ and _____ relative to mafic igneous rocks.
Greater silica, Lower melting temperature
What is the mineral name for table salt?
Halite
What are the economic uses of three common nonsilicate minerals?
Halite is used for common salt, gypsum is used in plaster, and graphite is used as pencil lead.
Intrusive and extrusive igneous rocks are classified based on what criteria?
How quickly the molten rock cools and crystallizes, and where this occurs with respect to Earth's surface.
How are igneous rocks formed?
Igneous rocks are formed by the cooling and crystallization of molten rock.
Olivine −
Independent tetrahedra
__________ SiO4 4- tetrahedra join with __________ ions to produce the mineral olivine in the rock peridotite.
Independent; Mg2+ and Fe2+
diorite
Intrusive igneous rocks
granite
Intrusive igneous rocks
Which of the following best describes a pegmatitic texture?
Large crystals that form in a fluid-rich environment late in crystallization
What is one way a glassy texture forms?
Lava cools rapidly.
Which of the following is true about mafic igneous rocks?
Mafic igneous rocks are rich in Fe, Mg, and Ca.
Based on the diagram shown in the video, name two minerals that are unlikely to coexist in the same igneous rock.
Muscovite and Pyroxene
Quartz −
Network
What are the two most abundant elements in Earth's crust?
Oxygen and silicon
What does an igneous rock with a pyroclastic texture tell a geologist?
The rock was likely formed by a violent volcanic eruption.
What is an accurate description of the silicon-oxygen tetrahedron?
The silicon-oxygen tetrahedron is a four-sided figure with a silicon atom in the middle bonded to four neighboring oxygen atoms.
Which of the following describes a texture containing bubble-shaped cavities?
Vesicular
What creates the small holes found in a vesicular texture?
Volatiles
Which nonsilicate mineral has carbonate as a negatively charged complex ion?
calcite
What are the two most common carbonate minerals?
calcite and dolomite
What is the most effective way to differentiate potassium feldspar from plagioclase feldspar?
e. Some cleavage planes of plagioclase feldspars have striations, whereas no potassium feldspars have striations.
What minerals make up half of Earth's crust?
feldspars
You have found a mafic rock with a phaneritic texture. What is a potential rock name?
gabbro
A(n) ________ is a silicate structure where no silica tetrahedra share any oxygen ions.
independent
The granitic igneous rocks that make up the Sierra Nevada Mountains in California and Nevada are ________.
intrusive
A phaneritic texture is characteristic of a(n) __________ igneous rock that cooled __________.
intrusive below the surface
When magma forms, it rises up through the crust. Why does magma rise?
it is less dense
What three components make up most magmas
liquid portion, solid portion, gaseous portion
s molten rock that is below the Earth's surface and retains most of its volcanic gases.
magma
What are the eight most common elements found in the Earth's crust, listed from most common to least common (by percent)?
oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium
Which of the following textures describes an igneous rock with anomalously large crystals?
pegmatitic
An igneous rock with a ______ texture solidified deep within Earth.
phaneritic
Silica tetrahedra are able to link into long chains that share oxygen ions through the process of ________.
polymerization
Which of the following textures indicates two stages of cooling and crystallization?
porphyritic
Only eight elements make up the vast majority of rock-forming minerals. Which of the following elements is not one of the eight?
potassium
The micas (biotite and muscovite) exhibit what type of silicate structure?
sheet
The ________ are the mineral class that accounts for more than 90 percent of the Earth's crust.
silicates
Which mineral group makes up most igneous rocks?
silicates
Which of the following pairs of elements are the most abundant in the continental crust?
silicon and oxygen
What factors influences the texture of an igneous rock?
the rate at which the rock cools, the amount of silica that is present in the magma from which it forms, and the amount of dissolved gases present in said magma
Fill in the blanks using the choices below: ____ are minerals typically found in igneous rocks that have a high silica content, whereas ____ are minerals that are typically found in igneous rocks with a low silica content.
Plagioclase feldspar and quartz; pyroxene and olivine
Andesite porphyry.
Porphyritic igneous rocks
Which two minerals define a felsic composition?
Quartz and Potassium Feldspar
Based on what you learned in this video, what minerals make up rhyolite?
Quartz, K-feldspar, and plagioclase feldspars, with relatively fewer biotite and amphiboles
Sulfides
S-
sulfates
SO42-
Muscovite −
Sheet
silicates
SiO24-
Pyroxene −
Single chain
What is the geologic definition of texture?
Size, shape, and arrangement of mineral grains in the sample
Slow cooling produces ________ crystals, whereas fast cooling produces ________ crystals.
Slow cooling produces large crystals, whereas fast cooling produces small crystals.
What does it mean if an igneous rock has an aphanitic texture?
The igneous rock exhibits mineral crystals too small to see with the naked eye.
Where do ultramafic rocks form?
upper mantle
