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Changing the composition of magma by incorporating surrounding host rock is known as ________.
assimilation
In which type of chemical bonding are electrons shared between adjacent atoms?
covalent
Which of the following is an example of a rock with an intermediate composition?
diorite
The ion at the center of a silicate tetrahedron is surrounded by ________.
4 oxygen ions
What is the difference between a dike and a sill?
A dike intrudes across sedimentary layers, and a sill intrudes between sedimentary layers.
What causes the same mineral to occur in varieties that are different colors?
A small amount of impurities in the crystal structure.
What causes a lack of cleavage in some minerals?
Bonds of equal strength in all directions
Suppose you found a mineral crystal that looked like topaz. What two minerals could you use in a scratch test to help determine if the mineral is indeed topaz?
Corundum and quartz
Why is glass is not considered a mineral?
Glass has a disorderly atomic structure.
The micas (biotite and muscovite) exhibit what type of silicate structure?
Sheet
What is a magma chamber called after the conduit has solidified and been exposed by erosion?
batholith
Which of the following minerals would be the first to crystallize?
olivine
Which igneous rock or magma has the least amount of light-colored silicates?
peridotite
Hardness describes a mineral's __________.
resistance to being scratched
Which of the following igneous rocks has a pyroclastic texture?
rhyolitic tuff
Which group of minerals are the most abundant in the Earth's crust?
silicates
Hornblende has _____ cleavage planes at _____ angles.
two; non-90° Submit
What is peridotite?
the rock making up the mantle
Drag the appropriate labels to their respective targets.
(Felsic, granite and rhyolite) (Intermediate, Diorite, and andesite) (Mafic, Gabbro, and Basalt) (Ultramafic, Peridotite, and Komatiite(rare))
Choose the answer below that does not belong with the others. Part complete Basalt Diorite Peridotite Granite
Basalt
________ is the aphanitic or fine-grained equivalent of gabbro.
Basalt
Why are the dikes and sills so easily distinguished in Sinbad Country?
Basalt and the hardened, baked zones are more resistant to erosion than the sedimentary rocks.
How is basaltic magma transformed into felsic magma?
Basaltic magma partially melts the continental crust, which is more felsic in composition.
How do batholiths, stocks, and laccoliths differ?
Batholiths are the largest type of igneous bodies and occur in a linear fashion with a distance of 100km or more; stocks are smaller than batholiths; laccoliths bend the sedimentary layers above them, whereas the sedimentary layers below remain relatively undeformed.
Why does partial melting result in a magma having a composition different from the rock from which it was derived?
Because different minerals melt at different temperatures, minerals that melt at lower temperatures will melt first, creating a magma that has a more felsic composition than the parent rock from which it formed.
What mineral is not scratched by a fingernail, but is scratched by a copper penny?
Calcite
________ reacts readily with acids such as hydrochloric.
Calcite
Which of the following best describes the term cleavage?
Cleavage is the splitting of minerals along natural planes of weakness. Submit
Which mineral property is the least useful for identifying minerals, and why?
Color is the least useful property for identification, as the same mineral type can be found in several different colors as a result of impurities in the mineral.
- Choose the answer below that does not belong with the others. Part complete Addition of water (hydration melting) Decompression melting Compression melting Temperature increase
Compression melting
How do sheet joints and exfoliation domes form in granite plutons?
Confining pressure on the plutons is removed through erosion of surrounding rock. Plutons then expand.
What is the difference between extrusive igneous rocks and intrusive igneous rocks?
Extrusive igneous rocks cool and solidify on the Earth's surface, whereas intrusive igneous rocks cool and solidify beneath the Earth's surface.
What minerals make up half of Earth's crust?
Feldspars
________ rocks are composed almost entirely of light-colored silicates.
Felsic
Once a source rock partially melts, what does it produce?
Felsic magma and mafic residue
Choose the answer below that does not belong with the others. Obsidian Gabbro Granite Rhyolite
Gabbro
Which of the following choices correctly classifies the four listed igneous rocks by composition?
Gabbro is mafic; obsidian is felsic; granite is felsic; andesite is intermediate.
Which of the following exhibits three sets of cleavage at 90° angles?
Galena
magma cools and consolidates without growth of mineral grains
Glassy
Which of the following is a mineral?
Ice
What is the basic foundation of Moh's hardness scale?
If a mineral scratches an object, then the mineral is harder than the object.
Which of the following best defines a mineral and a rock?
In a mineral the constituent atoms are bonded in a regular, repetitive, internal structure; a rock is a lithified or consolidated aggregate of different mineral grains.
__________ SiO4 4- tetrahedra join with __________ ions to produce the mineral olivine in the rock peridotite.
Independent; Mg2+ and Fe2+ Submit
Which of the following is a name for igneous rocks that crystalize beneath Earth's surface?
Intrusive and plutonic are both names for igneous rocks that crystallize beneath Earth's surface. Submit
Can you determine what type of igneous rock would result from various cooling histories and locations? Review the following rock photographs and determine their cooling histories. Place each image in its appropriate bin. Drag the appropriate items into their respective bins.
Intrusive igneous rocks diorite ,granite Extrusive igneous rocks Rhyolite Porphyritic igneous rocks Andesite Porphyry
Minerals must be solid, have an orderly atomic structure, have a recognized chemical composition, be naturally occurring, and __________.
be generally inorganic in origin
How are igneous rocks classified?
by their textures and compositions
Choose the answer that does not belong with the others.
calcite
Which two processes commonly generate magma?
decompression melting and wet melting (the addition of volatiles) Submit
Which of the following could cause rock to melt? CHOOSE ALL THAT APPLY
decrease in pressure, increase in temperature, change in composition
Partial melting results in magma that is ________ that of the rock from which it was derived.
different than
What is a roof pendant?
older rock capping the batholith. This rock would have been the roof of the magma chamber.
Consider Bowen's reaction series. Which mineral would you expect to see as a phenocryst in a porphyritic basalt?
olivine
Which of the following crystallizes at the highest temperature?
olivine
Which of the following minerals crystallize early in Bowen's reaction series?
olivine
Which of the following best describes the way minerals are classified?
on the basis of similar crystal structures and compositions
What are the six common nonsilicate mineral groups?
oxides, native elements, carbonates, halides, sulfides, sulfates Submit
Use your understanding of Bowen's reaction series to determine which of the rocks below will crystallize the fastest. The chemical composition of the rocks is: Diorite: amphibole, sodium- and calcium-rich plagioclase feldspar, pyroxene, and biotite Gabbro: pryoxene, calcium-rich plagioclase feldspar, amphibole, and olivine Granite: quartz, potassium feldspar, sodium-rich plagioclase feldspar, amphibole, muscovite, and biotite Peridotite: olivine, pyroxene, and calcium-rich plagioclase feldspar
peridodite
A(n) ________ texture represents a single, long period of cooling and crystallization.
phaneritic
Choose the answer below that does not belong with the others. Part complete phaneritic glassy pyroclastic aphanitic vesicular
phaneritic
In an igneous rock with a(n) ________ texture, the mineral grains are visible to the unaided eye.
phaneritic
What are the large crystals visible in this figure, and what do they indicate about the rock they formed in?
phenocrysts; precipitated out as magma cooled
Which term describes a rock with large crystals embedded in a matrix of smaller crystals?
porphyritic
Which of the following minerals would you find in abundance in a granitic (felsic) igneous rock? Choose all that apply.
potassium feldspar , and quartz
Which of the following are among the eight most abundant elements in Earth's crust? Choose all that apply.
potassium oxygen aluminum
Each atom of the same element, zinc for example, has the same number of ________.
protons in the nucleus
Which of the following is an extrusive igneous rock?
pumice
According to Bowen's Reaction Series, __________ is one of the first minerals to melt, but last to crystallize.
quartz
When magma cools too fast for mineral grains to grow, the resultant texture is called ________.
glassy
Based on the definition of a mineral, which of the choices below lists only minerals?
gold and ice
Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern. pumice granite welded tuff obsidian
granite
Visible quartz and potassium feldspar grains are the main constituents in a ________.
granite
Which of the choices below lists the four basic compositional groups of igneous rocks, ranging from the highest silica content to the lowest silica content?
granitic, andesitic, basaltic, ultramafic
The Mohs scale measures which property of minerals?
hardness
Choose the answer below that does not belong with the others.
hexavalent
Which of the following minerals is a ferromagnesian silicate?
hornblende
Looks glassy, dense and hard, like window glass
igneous
Rock is vesicular: has bubble-shaped holes/cavities or looks frothy.
igneous
Grains are mostly mineral crystals (crystalline texture) Crystals are randomly oriented in very hard rock
igneous rock
What is the name given to an atom that gains or loses electrons in a chemical reaction?
ion
In which type of bond are electrons transferred?
ionic bond
The amount or quality of light that is reflected from a mineral surface is known as __________.
luster
Which of the following describes the light reflecting characteristics of a mineral?
luster
Since color is not a very useful way to identify a mineral, what other optical property or properties can be used?
luster and streak
Suppose that an igneous rock with an intermediate chemical composition was partially melted before it resolidified. Which of the following best describes the chemical composition of the resolidified rock?
mafic
What lies underneath volcanic features at Earth's surface?
magma chambers and volcanic conduits
In a porphyritic volcanic rock, which mineral grains are the last to crystallize?
matrix or groundmass
Crystals are mostly garnet,mica's (Muscovite,biotite), serpentine,graphite,galena,or sphalerite
metamorphic
Look at the figure below. Which mineral is best represented by this figure?
mica
Match the following rocks to their equivalent aphanitic or phaneritic igneous rocks. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.
1.Rhyolite granite 2. Gabbro basalt 3. Andesite diorite
An atom's mass number is 14 and its atomic number is 7. How many neutrons are in its nucleus?
7
Which of the following is an accurate description of ionic bonding?
Atoms of different elements, having gained or lost electrons, form negative and positive ions that are bonded together by attractive forces between ions with opposite charges.
How are ions different from atoms?
An atom has a neutral charge because it has an equal number of protons and electrons, whereas an ion has a positive or a negative charge.
a magnifying glass or microscope is needed to see individual mineral grains
Aphanitic
You come across a whitish mineral in the field. You think it might be calcite, but you aren't sure. Which of the following would be the best way to determine if your sample is calcite?
Apply dilute hydrochloric acid to see if it fizzes.
Choose the statement that describes two processes that alter the composition of magma.
Assimilation occurs when magma that is injected into bedrock melts the rock directly surrounding it, incorporating it into the magma, whereas magma mixing occurs when two ascending bodies of magma join and mix together into a composition that is intermediate to the two original magmas. Submit
________ refers to the removal and isolation of early-formed mineral grains that can cause the composition of the remaining magma to change.
Crystal settling
How do light-colored igneous rocks differ from dark-colored rocks?
Dark-colored igneous rocks have a higher iron and magnesium content than light-colored rocks.
What causes an elevated geothermal gradient in a divergent plate setting?
Decompression melting of the mantle
Name the hardest and softest mineral on the Moh's scale.
Diamond (hardest) and talc (softest)
Select the correct description of dikes and sills.
Dikes are discordant igneous intrusions and sills are concordant igneous intrusions; both are tabular.
What is the difference between a dike and a sill? Dikes are horizontal; sills are vertical. Dikes are composed of igneous rock; sills are composed of sedimentary rock. Dikes crosscut sedimentary layers; sills pry between horizontal layers. Dikes are injected rapidly; sills are injected slowly. Dikes are made up of fine-grained basalt; sills are made up of course-grained basalt.
Dikes crosscut sedimentary layers; sills pry between horizontal layers.
Why is the monolith El Capitan in Yosemite National Park more resistant to erosion than other igneous plutons in the park?
El Capitan is unfractured.
Sort the element pairs into the bins for likely to bond or unlikely to bond according to the octet rule described in the introduction above and the periodic table of the elements. Refer to the periodic table below to help you answer this question.
Likely to Bond sodium and chlorine (Na and Cl) potassium and chlorine (K and Cl) magnesium and oxygen (Mg and O) potassium and bromine (K and Br) Unlikely to Bond lithium and argon (Li and Ar) hydrogen and neon (H and Ne) oxygen and krypton (O and Kr)
Layers are made of crystals, which are about the same size in all layers.
Metamorphic rock
Looks glassy, brittle, lightweight,opaque black; i.e. anthracite coal
Metamorphic rock
A scientist creates diamonds using high-pressure laboratory experiments. These diamonds are not considered minerals because which of the following requirements has been violated?
Minerals must occur naturally.
Which of the following correctly describes the difference between ferromagnesian and nonferromagnesian silicates?
Nonferromagnesian silicates are lighter in color and do not contain iron or magnesium. Submit
Choose the answer below that does not belong with the others. Potassium feldspar Sodium-rich pladioclase feldspar Quartz Olivine
Olivine
The progressive nucleation of minerals from the melt leaves the magma depleted in certain elements. This change in magma composition is called magmatic differentiation and accounts for the great variety of igneous rocks found in nature. The separation of liquid and solid phases through crystal settling further contributes to this diversity. Use your understanding of Bowen's reaction series and crystal settling to determine which of the following mineral associations should not be found in nature.
Olivine, potassium feldspar, quartz
They can be a liquid, solid, or gas. Submit
Oxygen
What are the two most abundant elements in Earth's crust?
Oxygen and silicon
________ is composed mainly of ferromagnesian minerals.
Peridotite
mineral grains are of roughly equal size and coarse enough to be seen without a microscope or magnifying glass
Phaneritic
rock has two or more, distinctly different-sized populations of mineral grains
Porphyritic
Which of the below statements accurately describes the components of an atom?
Protons, which have a positive charge, and neutrons, which have no charge, occupy the nucleus. Negatively charged electrons orbit the nucleus in shells.
Why is talc slippery whereas quartz is hard and glassy?
Quartz only has silicon-oxygen bonds, which are equally strong in all directions, whereas talc is made of sheet structures.
In the list below, indicate which of the items are minerals.
Quartz, Gold nugget
Grains are mostly sand,silt, or gravel ( a clastic texture)
Sedimentary rock
Layers are flat and soft or crumbly
Sedimentary rock
Drag and drop each mineral name into the correct mineral group. There is one mineral for each group.
Silicates Hornblende (Ca,Na)2(Mg,Fe,Al)5(Al,Si)8O22 (OH)2 Native elements Sulfur (S) Carbonates Malachite Cu2CO3(OH)2 Sulfides Galena (PbS) Sulfates Barite (BaSO4) Halides Fluorite (CaF2) Oxides Corundum (Al2O3)
Why are sills only located fairly close to the Earth's surface?
Sills form as magma intrudes with enough force to overcome the weight of the rocks above.
Why is decompression melting common at mid-ocean ridges but not at subduction zones?
Tectonic plates are moving apart at mid-ocean ridges, resulting in a lowering of pressure beneath the ridge. Tectonic plates are moving together at subduction zones, resulting in an increase of pressure under new mountains. Submit
When an atom gains an electron during a chemical reaction, which of the following is true?
That atom has a negative charge.
What role do water and other volatiles play in the formation of magma?
The addition of water and other volatiles allows the rock to melt at lower temperatures than if they had not been added.
Why is water a necessary component of the melting process in subduction zones?
The addition of water lowers the melting temperature of rock.
Which of the following best describes the term streak?
The color of a powdered form of a mineral produced by rubbing it across a hard surface.
Extrusive igneous rocks are typically finer grained than intrusive igneous rocks. Why?
The extrusive magma cools quickly so the mineral grains do not have time to grow.
How does the crystallization of igneous material occur?
The liquid igneous material cools, the ions within slow in their movement, and they pack more closely together. When sufficiently cooled, ions become confined to a crystalline arrangement.
Approximately how long did it take for the magma that fed each dike in Sinbad Country to be injected?
The magma was injected in a matter of hours to days.
What is Bowen's reaction series?
The order in which specific minerals form as a magma cools.
As a geologist, you always want to first locate your field site on a map. It helps other geologists to locate the field site for future studies and helps you look for relationships with data from nearby field sites. Determine where you are (your field site) in the world. Choose the map that best locates your field site.
The outcrop is located in the northeast corner of Minnesota. Take a moment to reflect on what you know about this area already. Is it an active plate boundary? Does it have mountains, volcanoes, glaciers, etc?
Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern. gabbro diorite basalt granite
basalt
Rock units tell us about Earth's past. If we find evidence of geologic processes that have directional components (direction of plate movement, folds and faults, mineral foliation, wind and water currents, etc.), we need to be able to accurately reconstruct those directions. In terms of the scientific method, documenting outcrop orientation helps other geologists recreate the field investigation step-by-step to confirm or refute previous findings and associated interpretations. Choose the most accurate representation of the outcrop's orientation given your vantage point (as viewed using the Gigapan in relation to the outcrop).
The photographer/image is looking towards the west. In other words, the outcrop faces east at the lake behind the photographer. Reflect on why it's important for a geologist to be specific about outcrop orientation and to record it accurately in a field notebook. If you don't recall why, reread the introduction to this question.
Which of the following is a probable history of an igneous rock with porphyritic texture?
The rock began cooling under the Earth's surface, but then was moved to above the Earth's surface where it finished cooling.
Which of the following best describes an aphanitic texture?
The rock is crystalline; mineral grains are too small to be visible without a magnifying lens or microscope.
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 one of the following is NOT true for minerals?
They can be a liquid, solid, or gas. Submit
How do the electrons behave in a mineral with metallic bonding?
They can move relatively easily from atom to atom inside the mineral.
Why don't the baked zones along the edges of the dikes and sills show evidence of metamorphism?
They weren't under enough pressure and didn't remain hot for a long enough period of time.
Below are some intrusive volcanic features that vary in size and shape that have been infused into host rocks. You will carefully examine their characteristics and identify the respective features. The top image shows the formation of these features and the two images below are the resulting features that evolved over time. In this image, "Time" is indicated by the red arrows. It progresses from top to bottom. Drag the appropriate labels to their respective targets.
Top to Bottom Sedimentary rocks Volcanic neck, Dike, Still, and Batholith
Refer to the periodic table of the elements to help you answer this question. If the number of protons in an electrically neutral atom is 92 and its mass number is 238, what is the name of that element, its number of electrons, and number of neutrons?
Uranium, 92 electrons and 146 neutrons Submit
What is the particular significance of valence electrons?
Valence electrons form chemical bonds between atoms by being transferred or shared.
Why are volcanic rocks often exposed at Earth's surface as hills, ridges, and mountains surrounded by areas of lower elevation?
Volcanic rocks are often more resistant to erosion than surrounding rock.
Where does the water involved in melting at subduction zones come from?
Water contained within minerals in the subducting plate is released during metamorphism.
How does decompression melting occur?
When hot, solid mantle rock ascends, it moves to areas of lower pressure. This reduction in pressure allows the hot material to melt into a less compressed liquid phase.
Choose the cross-section sketch that best represents the rock units you observe at this scale.
You have come to see that there are two main rock units stacked on one another. Next you will interpret the type of environment where this rock formed. Understanding the rock unit features in an outcrop can be important in order to develop some interpretation for how it formed. Next you will interpret the type of environment where this rock formed.
Which of the following is an example of a tabular intrusive body?
a dike
Please select the proper description of the silicon-oxygen tetrahedron.
a pyramidal shape with four triangular faces, an oxygen ion at each vertex, and a silicon ion at the center of the pyramid
a) In what kind of bonds are electrons shared in a common pool? b) In what kind of bonds are electrons transferred between atoms? c) In what kind of bonds are electrons shared between two atoms?
a) metallic, b) ionic, c) covalent
What large, overall igneous feature makes up the Sierra Nevada Mountains in California?
batholith
Which of the following igneous rocks exhibit aphanitic texture?
andesite, rhyolite
What are the six major igneous rock textures?
aphanitic, phaneritic, porphyritic, vesicular, glassy, and pyroclastic
In which two plate tectonic settings would one expect magma to be generated?
at a mid-oceanic ridge and at an oceanic-continental convergent boundary
The strong tendency of certain minerals to break along smooth, parallel planes is known as ________.
cleavage
Quartz exhibits __________.
conchoidal fracture
All of the following are factors that affect the generation of magma EXCEPT for ________.
crystal size
The process by which ions arrange themselves into orderly patterns during the cooling of a liquid is called ________.
crystallization
Partial melting results in a magma that is nearer the ________ end of the compositional spectrum than the parent rock from which it was derived.
felsic
The last minerals to crystallize on Bowen's Reaction Series result in igneous rocks with a ________ composition.
felsic
Regardless of their size, most rocks are made up of __________.
minerals
Which of the following minerals is a silicate?
muscovite
Which of the following is a felsic rock that started crystallizing within a large mass of magma but was then erupted on the surface of a continent?
rhyolite porphyry
Which group of minerals makes up most igneous rocks?
silicates
All silicate minerals contain ________ and ________.
silicon; oxygen
What physical property denotes the color of a powdered mineral?
streak
Which of the following is evidence of glaciation in Yosemite National Park?
striations in granite, U-shaped valleys
To what does the term "country rock" refer?
the crustal rocks into which igneous bodies intrude
What are the three components of magma?
the liquid portion (mobile ions of the eight most common elements found in the Earth's crust) called melt, the solid portion which consists of silicate mineral crystals, and the gaseous portion called volatiles
In a subduction zone, water driven from subducted oceanic crust causes __________.
the melting temperature of mantle rocks to decrease
Which of the following is a basic structural component of the most common mineral group?
the silicon-oxygen tetrahedron
Choose the answer that does not belong with the others.
triple-chain
When gas bubbles escape as lava solidifies, a ________ texture is formed.
vesicular
What is a volcanic conduit called after the conduit has solidified and been exposed by erosion?
volcanic neck