Chapter 4: Earth Materials

What happens at the atomic scale when a mineral cleaves or fractures?

* If all bonds have the same strength, they may be arranged in such a way that the mineral cleaves along three planes without passing through an atom. * If different bonds between atoms have different strengths, the mineral will cleave along the weakest bond directions. * If all bonds have the same strength, they may not be arranged in such a way as to allow cleavage planes to form mineral fractures.

What may be said of the mica mineral in the image?

* The mineral cleaved along one set of planes to split into thin sheets. * Bonds between atoms within sheets are stronger than those between atoms linking the sheets.

Dark-colored silicate minerals ______.

* form most of the oceanic crust and the mantle * include amphibole, pyroxene, olivine, garnet, and biotite * are called mafic minerals, as they contain high amounts of Mg and Fe

Light-colored silicate minerals ______.

* include quartz, potassium feldspar, plagioclase, and muscovite * are the most common minerals in the upper part of the continental crust

A silicon-oxygen tetrahedron ______.

* may join with other tetrahedra or cations to form different types of silicates and a wide variety of minerals * forms a building block for the vast majority of minerals on Earth * has one silicon atom bonded with four oxygen atoms

Rank the following by size in order from smallest to largest, with the smallest on the top. Mineral Single atom of an element Atomic Nucleus Electron

1. Electron 2. Atomic Nucleus 3. Single atom of an element 4. Mineral

Rank the following earth materials in order of their most likely occurrence, starting at Earth's surface. Think about moving from the crust to the mantle, and then to the outer and inner cores.

1. Granit and basalt 2. Increasing amounts of olivine and pryroxene 3. Minerals stable only at very high pressures; Fe-Mg silicates and oxides 4. Molten iron with nickel and some other elements 5. Crystalline iron and iron-nickel allow

Explain the dissolution of halite in water by putting the following steps in the correct order. Place the first event at the top and the last event at the bottom. Instructions

1. Halite crystals are immersed in water 2. The positive end of a water molecule becomes attracted to Cl anions, whereas the negative end of a water molecule becomes attracted to Na cations. 3. When the attraction of the polar water molecule to various cations and anions is strong enough, it pulls the ions away from the halite crystal. 4. Na cations become surrounded by negative sides of water molecules and Cl anions become surrounded by positive sides of water molecules. 5. As this process is repeated, the halite crystal are eventually dissolved in water.

Rank the following in order to show the precipitation of halite from water. Place the first event at the top and last event at the bottom.

1. Salty water begins to evaporate. 2. As water molecules move out of the liquid state, Na cations and Cl anions become more concentrated and are left behind. 3. Na cations and Cl anions become closer to each other and begin to bond. 4. Resulting NaCl pairs combine and begin to organize into an ordered structure: a halite crystal

What is true of atoms, elements, and minerals?

An atom is the smallest unit of an element that retains the characteristics of that element. An element is a type of atom that has a specific number of protons. Minerals are composed of chemically bonded elements.

What are two main ways that geologic minerals are used in society?

As a source of elements and compounds that we use to manufacture other products For some of their special properties, like color, density, and resistance to heat or abrasion, etc.

Which of the following mineral properties can be directly observed by the naked eye, without the need for testing supplies and equipment, and relate to the appearance of the mineral?

Color Luster Crystal shape Cleavage/fracture

Where would you expect to find the various mineral and rock types within Earth? Match the location with a description of its rock/mineral types. Continental Crust Oceanic Crust Upper Mantle Lower Mantle Outer Core Inner Core

Continental Crust--- Granite; light-colored silicate minerals quartz and feldspar Oceanic Crust--- Basalt and gabbro; plagioclase, pyroxene, olivine, and amphibole Upper Mantle--- Dark silicate minerals; olivine and pyroxene Lower Mantle--- Fe-Mg silicates and oxide minerals Outer Core--- Molten iron with some nickel and other elements Inner Core--- Crystalline iron and iron-nickel alloy

The image shows bonding for graphite (on the left) and diamond (on the right). Both minerals are made of carbon, so why do they have very different properties (why is diamond so hard, whereas graphite is so soft)?

Covalent bonds in both minerals are very strong, but intermolecular bonds between sheets in graphite are very weak.

Match the mineral property with its correct description. Crystal shape---- Color Cleavage Luster Fracture

Crystal shape---- A mineral that grows unobstructed by its surroundings can have a distinctive geometric form. Color----This is a useful, but not always reliable, property; very easily identifiable, but a single mineral may occur in several varieties of this property. Cleavage---Some minerals break in specific ways (along specific planes) because of their internal arrangement of atoms. Luster----This is the way light bounces off a mineral; may be earthy, pearly, metallic, silky, etc. Fracture---This occurs when a mineral has an atomic arrangement that does not contain cleavage planes along which the mineral breaks.

What gemstone is someone interested in if they are searching for a kimberlite pipe?

Diamond

Match the gemstone with its geologic environment of formation. Diamonds Ruby, Sapphire, and Emerald Opal Pear and Amber

Diamonds---Deep under the mantle; high temperature and extremely high pressure; brought to the surface in kimberlite pipes Ruby, Sapphire, and Emerald--- Choice In pegmatites that crystallized from magma containing relatively high amounts of water Opal---Not a mineral (does not have orderly crystalline structure); forms in volcanic rocks and some sedimentary rocks with voids, as silicon-rich water fills the voids Pear and Amber --- Not minerals; form through organic processes

Match the location with its two most common elements. Earth's Crust Universe The Entire Earth

Earth's Crust--- silicon and oxygen Universe--- hydrogen and helium The Entire Earth--- oxygen and iron

Which of the following are tests we can quickly and easily perform (even in the field) to help us identify a mineral?

Effervescence Streak Magnetism Hardness

What factors contribute to a water molecule having polarity?

Electrons spend more time around the oxygen atom and give the molecule a negative side and two positive ends on the other side. Oxygen more strongly attracts electrons than hydrogen does. Hydrogen atoms are grouped on one side of the oxygen atom.

Which of the following are true of the organization of rows and columns in the Periodic Table?

Elements in the last column are noble gases and have full outer shells. Rows indicate the number of electron shells. Elements in the first column have only one electron in their outer shell.

Which are true of the Periodic Table?

Grouped elements tend to have similar chemical properties (like the two different types of metals, the nonmetals, noble gases, etc.). It includes an element's atomic symbol and atomic number. It begins with the lightest element and advances to higher atomic numbers and heavier elements from left to right and from top to bottom.

Match the mineral property with how it is tested. Hardness Streak Effervescence Magnetism

Hardness----Use reference minerals and other standardized materials to see which are scratched by an unknown mineral and which are not. Streak-----Observe color left behind on a porcelain plate when mineral is dragged across it. Effervescence---Observe if a dilute HCl solution bubbles when placed on mineral. Magnetism----Observe if magnet sticks to mineral.

Which of the following is not a required criterion for a substance to be classified as a mineral?

Human Made

Below are descriptions of silicates and non-silicates. Choose all those that represent non-silicates.

Includes calcite, pyrite, and hematite Do not contain the Si-O tetrahedron

Match the chemical bond type with its description. Ionic Covalent Metallic Intermolecular force

Ionic--- Forms because of the attraction of two oppositely charged ions, which are created when atoms loan one or more electrons to another atom Covalent--- Forms when two atoms share an electron Metallic--- Forms when electrons are shared widely by many atoms Intermolecular force--- Type of weak bond formed when one molecule is attracted to another molecule

Which of the following are true regarding the image?

It shows a silicon-oxygen tetrahedron. Most silicates form from this SiO4-4 complex.

Which of these are associated with the formation of diamonds and bringing them to the surface?

Kimberlite pipes Very high pressures

Which of the following are criteria that must be fulfilled for a substance to be considered a mineral?

Naturally occurring Inorganic Crystalline solid

Match the cleavage type with its description. One Direction Two Perpendicular Directions Two Non-Perpendicular Directions Three Perpendicular Directions Three Non-Perpendicular Directions

One Direction----Cleaves along one set of parallel planes, forming thin sheets Two Perpendicular Directions---Cleaves along two sets of planes that result in 90 degrees steps along broken crystal faces Two Non-Perpendicular Directions---Choice Cleaves along two sets of planes that intersect at angles other than 90 degrees Three Perpendicular Directions---Cleaves along three sets of planes and the mineral commonly breaks into cubes Three Non-Perpendicular Directions--- Choice Cleaves along three sets of planes and the mineral commonly breaks into rhombs

The three most abundant elements in Earth's crust are ______.

Oxygen Silicon Aluminum

Match the term with its correct description. Periodic Table Atomic Symbol Atomic Number Metals Nonmetals Noble Gases

Periodic Table--- This organizes all the chemical elements according to atomic number and electron orbitals. Atomic Symbol---This is one or two letters representing the name of an element. Atomic Number---This is the number of protons in an atom. Metals Nonmetals---These elements include O and Si and typically bond with both types of metallic elements to form minerals. Noble Gases---These include the elements Ar and He; these do not readily combine with other elements.

Match the mineral with its use in society. Quartz Hermatite Clays Gypsum

Quartz--- May be used for chemical components; the element silicon is used to create computer chips and is mostly derived from this mineral. Hermatite---May be used for chemical components; iron is the main ingredient in steel and is mostly mined from minerals such as this. Clays--- May be used for its physical properties; this mineral is used to produce brick, cement, and ceramics. Gypsum--- May be used for its physical properties; sheetrock and plaster products are made from this mineral.

Which of these gemstones is a variety of the mineral corundum?

Ruby Sapphire

Match the gemstone to its description. Ruby Peridot Emerald Citrine

Ruby--- The red variety of corundum Peridot--- The gem variety of the mineral olivine Emerald--- The green verity of beryl Citrine--- The yellow-orange variety of quartz

Which of the following terms refers to the compound SiO2?

Silica

Match the term with its description. Silica Silicon Silicone

Silica---A compound containing only silicon and oxygen in a ratio of 1:2 (SiO2) Silicon---The fourteenth element of the Periodic Table; term may also be used to describe a synthetic material used to make computer chips Silicone---A synthetic material (often used for grease or caulk) in which carbon is bonded to silicon atoms to keep the material in long chain

Match the rock-forming mineral class with its description. Silicates Carbonates Oxides Halides Sulfates Sulfides Native Minerals

Silicates---The most important mineral group on Earth; contain silicon and oxygen; example is quartz Carbonates---Carbon and oxygen bonded in a triangular arrangement; example is calcite Oxides---Oxygen bonded with a metal; example is hematite Halides---Contain chlorine or fluorine; example is halite Sulfates---Sulfur that is only bonded to oxygen; example is gypsum Sulfides---Sulfur bonded with a metal; example is pyrite Native Minerals---Minerals that contain only a single element; example is copper

The mineral in the image is quartz. Take a look at the irregularly broken face at the center of the crystal and determine which of the following is true.

The mineral has fractures, as it lacks cleavage planes.

If a mineral lacks planes along which it may cleave, what will occur?

The mineral will fracture in an irregular pattern.

Which of the following best describes the materials that cover Earth's surface?

There are many different materials, and they vary by location.

Match each observation to the geologic scale at which it would be made. Thin Section Hand Specimen Cliff Face

Thin Section-----Light passes through mineral crystals; internal structure of mineral crystals is seen Hand Specimen---Different-colored grains are present; minerals have different colors Cliff Face--- Rock looks homogeneous; rock appears to be one color

At which of the following scales would you be most successful in determining the mineral content of a rock?

Thin section

Which of the following are common types of cleavage (and their associated minerals/mineral groups)?

Three non-perpendicular directions (calcite) Two perpendicular directions (pyroxene) One direction (mica) Two non-perpendicular directions (amphibole) Three perpendicular directions (halite)

Earth's surface is covered with many different types of materials. True or Fals

True

The carbon atoms in diamond are held together by ______ bonds, and the sheets of carbon atoms in graphite are held together by _______ bonds, making these two minerals ______ each other.

covalent; intermolecular; very different from

Over 90% of Earth's___________ is composed of silicate minerals.

crust

Silicate minerals that are rich in magnesium and iron are_________ colored.

dark

The formation of many gemstones such as ruby and sapphire are associated with ______ conditions.

hot water high pressure high temperature

The most common minerals in the upper part of the continental crust are ______________ colored silicates. They are felsic in composition, and their color is a direct result of their elemental composition.

light

Minerals that do not contain silicon are classified as ______.

nonsilicates

Rows on the Periodic Table correspond to the ______, whereas columns correspond to the ______.

number of electron shells; number of electrons in the outermost shell