CHAPTER 4

Match the location on the image with its correct class of rock-forming minerals.

1. Silicates 2. Carbonates 3. Oxides 4. Halides 5. Sulfates and sulfides 6. Native minerals

Order the three states of matter according to the orderliness of its atoms, with the most orderly on top.

1. Solid 2. Liquid 3. Gas

Silica

A compound containing only silicon and oxygen in a ratio of 1:2 (SiO2)

Crystal shape

A mineral that grows unobstructed by its surroundings can have a distinctive geometric form.

Silicone

A synthetic material (often used for grease or caulk) in which carbon is bonded to silicon atoms to keep the material in long chains

Pharmaceutical mineral

Always composed of a single chemical element; potassium

What is true about asbestos?

Amphibole (blue) asbestos poses a severe health risk. Chrysotile (white) asbestos does not pose a significant health risk unless breathed in large amounts for a long time.

Carbonates

Carbon and oxygen bonded in a triangular arrangement; example is calcite

The common nonsilicate mineral groups include which of the following?

Carbonates Sulfates Oxides Sulfides Halides

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?

Cleavage/fracture Luster Color Crystal shape

Which of the following is not a characteristic of rocks with clastic textures?

Composed of crystals with interlocking minerals (crystalline)

Carbonates

Contain (CO3)2-; most important are calcite and dolomite; typically precipitate from water or originate organically

Sulfides

Contain (S)-2 bonded with Fe, Pb, Zn, or Cu; principal metal ores in many mines; include pyrite and galena

Halides

Contain chlorine or fluorine; example is halite

Oxides

Contain oxygen bonded with metals (most commonly H and Fe); include ice, hematite, and magnetite

K-Feldspar

Contains Al, K, Na, and Ca; generally pink to cream; two directions of cleavage

Pyroxene

Contains Ca, Na, Al, Fe, and Mg; black, dark brown, green, or white; crystals often equant; two perpendicular cleavages at 90o

Amphibole

Contains Mg, Fe, Ca, Na, and Al; black, green, or white; long, radiating crystals; cleavage at 60o and 120o

Which of the following are attributes that are evaluated to classify crystalline and clastic rocks?

Crystal/clast shape Crystal/clast size Presence/absence of layers Minerals present

Hand specimen

Different-colored grains are present; minerals have different colors

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

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

Rocks composed of various pebbles and sand

Does not have a chemically consistent composition throughout

True or false: A geologist must know all of the different types of minerals in order to correctly identify and classify most rocks.

False

Crystalline

Forms in high-temperature environments; minerals are interlocking

Which of the following structures are commonly formed by silicon-oxygen tetrahedra?

Frameworks

Double chains

Half the tetrahedra share two O atoms and half share three; minerals cleave parallel to structure and along two planes at 60o and 120o.

Which of the following help determine the outward shape of a crystal?

How the crystal's growth was affected by the material around it The arrangement of atoms in the crystal

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

Human-made

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

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. 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 be arranged in such a way that the mineral cleaves along three planes without passing through an atom.

Which are true of the Periodic Table?

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

Which of the following are true regarding the image?

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

Thin section

Light passes through mineral crystals; internal structure of mineral crystals is seen

Native minerals

Minerals that contain only a single element; example is copper

Olivine

Most common mineral in upper mantle; distinctively olive-green; contains Fe and Mg; no cleavage

What type of electrical charge does the silicate tetrahedron have?

Negative

Human-made diamond

Not naturally occurring

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.

Plagioclase

One of the two most common feldspar minerals; contains K, Na, Ca, and Al; usually white to light gray; may have striations on crystal faces

Match the color represented on the image of the Periodic Table with the correct description of the chemical elements grouped within it. If you need help with the colors, they are described in the text.

Orange - Alkali and alkali earth metals (main group metals) Yellow - transition metals Green - Nonmetals Tan - Noble gases Purple and blue - actinide and lanthanide series

Biotite

Part of the mica family; black or brown; contains K, Al, and varying Fe and Mg; one dominant direction of cleavage

Muscovite

Part of the mica family; one direction of cleavage; partially transparent to silvery gray; contains K, Al, and a component of water (OH)-

Which of these are light-colored silicate minerals?

Potassium feldspar Na-rich plagioclase Quartz

Human tooth

Produced by organic/life processes

Obsidian

Randomly arranged atoms

Cliff face

Rock looks homogeneous; rock appears to be one color

Quartz

SiO2; Mohs hardness of 7; may be many colors but is often white to nearly transparent; no cleavage

Which of the following terms refers to the compound SiO2?

Silica

Cleavage

Some minerals break in specific ways (along specific planes) because of their internal arrangement of atoms

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

Streak Magnetism Hardness Effervescence

Sulfides

Sulfur bonded with a metal; example is pyrite

Sulfates

Sulfur that is only bonded to oxygen; example is gypsum

Frameworks

Tetrahedra share four O atoms; quartz, with no cleavage, or feldspar with cleavage.

Which of the following may be said about the mineral whose atomic structure is represented in the image?

The crystal shape formed by the mineral is a cube. The represented mineral is halite (NaCl). Na and Cl atoms alternate in the crystal lattice structure

Silicon

The fourteenth element of the Periodic Table; term may also be used to describe a synthetic material used to make computer chips

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.

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

The mineral will fracture in an irregular pattern.

Silicates

The most important mineral group on Earth; contain silicon and oxygen; example is quartz

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

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

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

Thin section

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.

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.

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

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

Hardness

Use reference minerals and other standardized materials to see which are scratched by an unknown mineral and which are not.

Geologic mineral

Usually composed of two or more chemical elements, e.g. Halite (NaCl)

Light-colored silicate minerals ______.

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

There are five different silicate minerals commonly used as a fire-retardant and insulator that are described as _____________ and not all of them pose a severe health risk as commonly believed.

asbestos

There are five different silicate minerals commonly used as a fire-retardant and insulator that are described as ______________ and not all of them pose a severe health risk as commonly believed.

asbestos

Magnetite and hematite occur together in layered sedimentary rocks called ______.

banded iron formation

The rocks marble and limestone and the minerals aragonite, calcite, and dolomite are all different forms of _________ minerals.

carbonate

The ______ family of minerals has a sheet-silicate structure so weakly bonded that the sheets easily slip past one another to give them a slippery feel, and their structure often expands when water is added.

clay

The mineral halite (pictured) has a(n) ______ atomic structure, whereas quartz has a(n) ______ atomic structure that includes one Si atom surrounded by four O atoms, and fluorite has a(n) ______ atomic structure that includes two oppositely pointing, four-sided pyramids of Ca and F atoms.

cubic; tetrahedron; octahedron

Silicate minerals that are rich in magnesium and iron are ___________-colored.

dark

The specific gravity of a mineral is that mineral's ______ compared to that of freshwater.

density

Which of the following is a characteristic of crystals and/or clasts that is not used in classifying a rock?

density

Minerals in vitamins are composed of individual chemical ______, whereas geologic minerals usually consist of two or more.

elements

Clastic

forms in low-temperature environments at or near Earth's surface

A silicon-oxygen tetrahedron ______.

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

A substance that has an ordered internal structure will ______.

have atoms arranged in a regular, repeating pattern be considered crystalline

Clay ______.

is a term that may be used as a particle size designation (less than 0.002 mm) or to describe a family of minerals minerals have a sheet-silicate structure, but atoms are bonded weakly minerals form by weathering of rocks at Earth's surface or from chemical reactions in hot water

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

Dolomite is very similar to calcite, but some of the calcium in its structure has been replaced with ______.

magnesium

Considers the properties of ice? Is it a mineral or nonmineral?

mineral

Independent tetrahedra

minerals (like olivine) do not break along clearly defined planes; all bonds are almost equally strong.

A geologist who is also a mineralogist would generally study _____.

minerals such as quartz and halite

Rocks are composed of ______, and minerals are composed of ______.

minerals; elements

In order for a crystal to attain a well-defined shape, it ______.

must grow unimpeded by surrounding material likely grows in an open space, in water or in magma

The silicon-oxygen tetrahedron has a ______ charge, and so attracts ______.

negative; cations

A substance that has well-defined geometric crystals is likely to have a(n) ______ internal structure.

ordered

Oxides

oxygen boned with a metal; example is hematite

Over 90% of the Earth's crust consists of _______________.

silicate materials

The ratio of density of a mineral to that of freshwater is called the mineral's ______.

specific gravity

Sheets

tetrahedra share three oxygen atoms; cleavage of minerals(like micas and clays) is in one main direction.

Single Chains

tetrahedra share two O atoms and are strongly bonded; cleavage is parallel to the bonded tetrahedra

The way the grains and minerals are arranged is the ______ of the rock.

texture

The word that geologists use to describe how grains and minerals are arranged in a rock is ______________.

texture

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

There are more than 5,000 known minerals, most of which are ______.

uncommon to rare