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Chapter 3Chapter 3Minerals Minerals
The Building Blocks of The Building Blocks of RocksRocks
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Minerals OutlineMinerals Outline
1. What are minerals?1. What are minerals?2. Matter, atomic structure & chemical bonds2. Matter, atomic structure & chemical bonds3. World of minerals, crystals & composition 3. World of minerals, crystals & composition 4. Mineral groups & differences4. Mineral groups & differences5.5. GeoGeo--inSightinSight –– precious metalsprecious metals6.6. Physical properties Physical properties 7.7. GeoGeo--Focus: MicasFocus: Micas8.8. RockRock--forming mineralsforming minerals9. Minerals formation9. Minerals formation10.Natural resources 10.Natural resources
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What are minerals?What are minerals?
Minerals Minerals are the are the building building blocks of blocks of rocks. rocks.
Introduction: MineralsIntroduction: Minerals
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IntroductionIntroductionWhat is a mineral?
A mineral is
– Naturally – Inorganic– Crystalline solid– Characteristic physical properties– Specific chemical composition.
Gemstones – precious or semi-precious minerals or rocks used for decorative purposes
Fig. 3.1 a, p. 62
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IntroductionIntroductionAre amber and pearls minerals?
– Amber is considered a semiprecious “stone,” but it is not a mineral because it is organic and not crystalline.
– Pearls, although they grow in mollusks, are minerals because they are crystalline and meet the other criteria for minerals.
Fig. 3.1 b-c, p. 62 Changing Earth 5eChanging Earth 5e
Matter Matter –– What is It?What is It?Atoms and Elements
– Matter: anything that occupies space & has mass (states/phases of matter: liquids, gases & solids)
– All matter is composed of chemical elements, which are themselves composed of atoms.
– Atoms consist of a nucleus, of protons and neutrons, and electrons that circle the nucleus.
– Elements are defined on the basis of the number of protons in the nucleus of an atom (i.e., the atomic number).
– Another characteristic of an atom is its atomic mass, the sum of the numbers of protons and neutrons in the nucleus.
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Atomic structure of matter: Atomic structure of matter:
Atoms consist of a:Atoms consist of a:
Nucleus of protons Nucleus of protons and neutrons and and neutrons and Electrons as a as a cloud of moving cloud of moving particles particles surrounding surrounding (spinning around) (spinning around) the nucleus.the nucleus.The (The (--) electrons ) electrons balance (+) protonsbalance (+) protons
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bonds
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Matter Matter –– reviewreview
1. The number of protons in an atom’s nucleus determines its atomic number,
2. An atom’s atomic mass number is the total number of protons and neutrons in the nucleus. So, for example, if an atom has 6 protons and 8 neutrons its atomic number and mass numbers are 6 and 14, respectively.
Fig. 3.4, p. 64
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6 p8 n
14C (Carbon 14)13C (Carbon 13)
6 p7 n
Nucleus
6 p6 n
12C (Carbon 12)
Isotope: some elements may have more or less neutrons than typical form, hence different in atomic mass. Some are radioactive (decay to other form).
Carbon: 12C (6p+6n)- typical, 14C (6p+8n)- radioactive
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Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bonds
Bonding and Compounds
• Atoms are joined to one another by forces known as bonding.
• Atoms of different elements which are bonded to one another form compounds.
Fig. 3.5a, p. 65
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Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsBonding and CompoundsIonic Bonds - Ionic bonds transfer an electron, with opposite electrical charges attracting one another
Halite is a compound formed by the ionic bondingof sodium atoms to chlorine atoms. Note the atom sizes & arrangement (left) to form cubic crystals (right).
Fig. 3.5, p. 65 Changing Earth 5eChanging Earth 5e Fig. 3-5a, p. 65Stepped Art
Sodiumatom11 p+
11 e–
Sodiumion
11 p+
10 e–
+
Chlorineion
17 p+
18 e–
–
Chlorineatom17 p+
17 e–
electron transfer
Halite forms by transfer of sodium atoms electron to chlorine atom outer electron ring and resulting ionic attraction bonds the atoms together.
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Chlorideion
Sodiumion
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsionic bond & electron transfer in 3D
A negatively charged ion, is known as an anion. A positively-charged ion, is known as a cation
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Sodium and chloride ionspack in a cubic structure.
Chlorideion
Sodiumion
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsionic bond & electron transfer in 3D
A negatively charged ion, is known as an anion. A positively-charged ion, is known as a cation
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Sodium and chloride ionspack in a cubic structure.
Chlorideion
Sodiumion
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsionic bond & electron transfer in 3D
A negatively charged ion, is known as an anion. A positively-charged ion, is known as a cation
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Sodium and chloride ionspack in a cubic structure.
Each cation is surrounded bysix anions, and vice versa.
Chlorideion
Sodiumion
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsionic bond & electron transfer in 3D
A negatively charged ion, is known as an anion. A positively-charged ion, is known as a cation
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Sodium and chloride ionspack in a cubic structure.
Each cation is surrounded bysix anions, and vice versa.
Chlorideion
Sodiumion
NaCl crystal
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsionic bond & electron transfer in 3D
A negatively charged ion, is known as an anion. A positively-charged ion, is known as a cation
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Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsionic bond & electron transfer in 3D
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Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bonds
Electrical charges of atomic ionsElectrical charges of atomic ions
CationCation –– positively chargedpositively chargedAnion Anion –– negatively chargednegatively charged
Atomic ions arrange themselves Atomic ions arrange themselves according to charge and size.according to charge and size.
The cations of common mineral are small, while most anions are larger.
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Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bonds
Crystalline structure are determined by how anions are arranged and how the cations fit between them.
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Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bonds
Bonding and CompoundsCovalent Bonds – in covalent bonding the atoms share electrons in outer shell.
Can createvery strong mineral but depends on arrangementof bonds.
Example: Carbon bonds in Diamond vsGraphite Fig. 3.6, p. 66 Changing Earth 5eChanging Earth 5e
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsBonding and CompoundsCovalent Bonds – in covalent bonding the atoms share electrons.
Can createvery strong mineral but depends on arrangementof bonds.
Example: Carbon bonds in Diamond vsGraphite Fig. 3.6, p. 66
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Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bondsBonding and CompoundsCovalent Bonds – in covalent bonding the atoms share electrons in outer shell.
Can createvery strong mineral but depends on arrangementof bonds.
Example: Carbon bonds in Diamond vsGraphite Fig. 3.6, p. 66 Changing Earth 5eChanging Earth 5e
Matter, atomic structure & chemical bondsMatter, atomic structure & chemical bonds
Bonding and Compounds
Metallic bonds– Metallic bonds result from extreme electron sharing.– Not common, primary metal minerals/ores
Van der Waals bonds– Van der Waals bonds are an extremely weak bond
without available electrons to form an attraction.– In graphite the sheets with covalent bonding are
held together by Van der Waals bonding
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World of MineralsWorld of Minerals
Mineral is composed of a naturally occurring inorganic substance
We define a mineral as naturally occurring– This excludes all synthetic substances made by
man like synthetic diamonds and rubies.
The term inorganic deserves special consideration– Animal and plant matter are not minerals– Certain organisms, however, do use minerals,
like calcite and quartz, to form their shells
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World of MineralsWorld of MineralsCrystals: A mineral is a crystalline solid.
So why is it that not all mineral specimens show well-developed crystals?
As minerals form and grow, they may merge with one another to form a mosaic of interlocking crystalline solids that show no obvious crystals.
Nevertheless, individual minerals within this mosaic have their atoms arranged in a specific three-dimensional framework.
Fig. 3.8 a-b, p. 67
Smoky Quartz
Rose Quartz
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Crystalline shape of the mineral is influenced by shape of individual crystal which starts the growth of mineral.
• With ideal conditions minerals can form perfect crystals.• Development of large crystal form is uncommon • Often find one or more faces/planes of the crystal form
World of MineralsWorld of Minerals
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World of MineralsWorld of Minerals
Composition: A mineral has a specific chemical composition.
– By definition native elements are made up of only one chemical element, such as gold (Ag) and diamond (C).
– Most minerals are composed of two or more chemical elements, such as quartz (SiO²).
Geo-inSight 6., p. 73
Native Silver
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Mineral Groups, CompositionMineral Groups, Composition
Fig. 3.10, p. 69
How many minerals are there?
There are thousands of known minerals, but commonly find only about 30 minerals on or near surface.
Most minerals can be grouped into 8 classes by chemical composition, with each class defined by anion charge.
The majority of minerals are composed of common elements.
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Composition of the Crust
By volume ≈99% of the Earth's crust consists of only 8 elements:• OXYGEN—O• SILICON—Si• ALUMINUM—Al• IRON—Fe• CALCIUM—Ca• SODIUM—Na• POTASSIUM—K• MAGNESIUM—Mg
Mineral Groups, Composition Mineral Groups, Composition
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MineralMineral GroupsGroups, Composition , Composition
There are 92 naturally occurring elements, but only 8 are common in Earth’s crust.
Fig. 3.10, p. 69
Among the 8 elements,–Oxygen (47%) &
silicon (28%) aremost common in the crust.
–Most common minerals are madeup of oxygen, silicon, and one or more other elements.
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Chemical classes of minerals (8 classes)• Silicates – contain O & Si (abundant)
(Olivine - MgSiO4) • Carbonates – contain C & O (anion CO3
2-) • Oxides - contain O & metallic cation
(Hematite - Fe2O3) • Sulfides - contain S & metallic cation
(Pyrite - FeS2)• Sulfates - contain SO4 & metallic cation
(Anhydrite CaSO4) • Halides – contain Cl, F, I, or Br
(Halite NaCl, Floride-CaF2)• Hydroxides – contain OH• Native elements – masses of all the same element
metallically bonded, gold & silver
Mineral Groups, Composition Mineral Groups, Composition
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Mineral Groups, Composition Mineral Groups, Composition
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Mineral GroupsMineral Groups
Table 3.1, p. 69
Most of the more than 3,500 known minerals are silicates(compounds of silicon and oxygen, and other elements).
Additional common mineral groups include
• carbonates, • oxides, • sulfides, • sulfates, & • halides.
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Silicate ion (SiO44–)
Oxygen ions(O2–) Silicon ion
(Si4+)
Mineral Groups: Mineral Groups: silicate minerals6 Rock forming minerals: silicate minerals
Tetrahedra are the basic building blocks of all silicate minerals. About 95% of Earth’s minerals are silicates.
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Silicate ion (SiO44–)
Oxygen ions(O2–) Silicon ion
(Si4+)
The silicate ion forms tetrahedra.
Quartzstructure
Quartz is a silicate polymorph.
Mineral Groups:
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Silicate ion (SiO44–)
Oxygen ions(O2–) Silicon ion
(Si4+)
The silicate ion forms tetrahedra.
Quartzstructure
Tetrahedra arranged in other ways are characteristic of other silicates minerals and determine their cleavage direction.
Mineral Groups:
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Mineral GroupsMineral GroupsSilicate Minerals
– composed of the silica tetrahedra
Fig. 3.12, p. 70
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Mineral Chemical formula
Cleavage planesand number of
cleavage directionsSilicate
structure Specimen
1 plane Isolatedtetrahedra
Olivine (Mg, Fe)2SiO4
Isolated tetrahedrons
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Mineral Chemical formula
Cleavage planesand number of
cleavage directionsSilicate
structure Specimen
1 plane Isolatedtetrahedra
2 planes at 90°Single chains
Olivine
Pyroxene
(Mg, Fe)2SiO4
(Mg, Fe)SiO3
Single Chain Tetrahedrons
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Mineral Chemical formula
Cleavage planesand number of
cleavage directionsSilicate
structure Specimen
1 plane Isolatedtetrahedra
2 planes at 90°Single chains
2 planes at 60°and 120° Double chains
Olivine
Pyroxene
Amphibole
(Mg, Fe)2SiO4
(Mg, Fe)SiO3
Ca2(Mg, Fe)5Si8O22(OH)2
Double Chain TetrahedronsChanging Earth 5eChanging Earth 5e
Mineral Chemical formula
Cleavage planesand number of
cleavage directionsSilicate
structure Specimen
1 plane Isolatedtetrahedra
2 planes at 90°Single chains
2 planes at 60°and 120° Double chains
1 plane Sheets
Olivine
Pyroxene
Amphibole
Micas
(Mg, Fe)2SiO4
(Mg, Fe)SiO3
Ca2(Mg, Fe)5Si8O22(OH)2
Muscovite:KAl2(AlSi3O10)(OH)2
Biotite:K(Mg, Fe)3AlSi3O10(OH)2
Continous Sheets Tetrahedrons
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Mineral Chemical formula
Cleavage planesand number of
cleavage directionsSilicate
structure Specimen
1 plane Isolatedtetrahedra
2 planes at 90°Single chains
2 planes at 60°and 120° Double chains
1 plane Sheets
Olivine
Pyroxene
Amphibole
Micas
Feldspars
2 planes at 90° Three-dimensionalframework
(Mg, Fe)2SiO4
(Mg, Fe)SiO3
Ca2(Mg, Fe)5Si8O22(OH)2
Muscovite:KAl2(AlSi3O10)(OH)2
Biotite:K(Mg, Fe)3AlSi3O10(OH)2
Orthoclase feldspar:KAlSi3O8
Plagioclase feldspar: (Ca, Na) AlSi3O8
3-D Networks of Tetrahedrons
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Mineral GroupsSilicate Minerals
– Ferromagnesian silicates - made up of iron, magnesium, or both combined with other elements.• dark in color and dense
Fig. 3.12 a, p. 70Fig. 3.13 a, p. 74
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Mineral GroupsMineral GroupsSilicate Minerals
– Nonferromagnesian silicates - lack iron and magnesium• light colored
Fig. 3.11, p. 70Fig. 3.13 b, p. 74 Changing Earth 5eChanging Earth 5e
Mineral Groups Mineral Groups Carbonate Minerals
– All carbonate minerals have the carbonate radical (CO³)-²as in calcite (CaCO³) and dolomite [CaMg(CO³)²].
– Carbonate minerals are found mostly in the sedimentary rocks limestone and dolostone.
– Carbonates are derived from the shells and hard parts of marine organisms or are precipitated from seawater as evaporites.
Fig. 3.11, p. 70Fig. 3.14, p. 75
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Mineral GroupsMineral GroupsOther Mineral Groups
– Native Elements
– All native elements are composed of a single element.
– Gold, copper and diamonds commonly occur as native elements.
Geo-inSight 6., p. 73 Changing Earth 5eChanging Earth 5e
Mineral GroupsMineral GroupsOther Mineral Groups
– Sulfides– All sulfide minerals contain sulfur plus a metallic
element as in galena (PbS) and pyrite (FeS²). – Sulfide minerals are found in all types of rocks.
They commonly form along mid-oceanic ridges
Fig. 3.14b, p. 75Fig. 3.15a, p. 78
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Mineral GroupsMineral Groups
Other Mineral Groups – Sulfates
– All sulfate minerals have the sulfate radical (SO4 -² ) as in gypsum (CaSO4 2H2O)
– Sulfate minerals are common in deserts, forming from evaporation of water
Fig. 3.11, p. 70 Changing Earth 5eChanging Earth 5e
Mineral composition and structure produce unique physical properties.
– Color
– Hardness
– Cleavage
– Crystal form
– Specific gravity
Physical Properties of MineralsPhysical Properties of Minerals
p. 60
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Physical Properties of MineralsPhysical Properties of MineralsLuster and Color
– Luster is the quality and intensity of light reflected from a mineral and is characterized as metallic or nonmetallic.
– Color, in contrast, is a visual quality of minerals that results from the way they absorb or transmit light.
Fig. 3.15a, c, p. 78 Changing Earth 5eChanging Earth 5e
Physical Properties of MineralsPhysical Properties of MineralsCrystal Form
– Crystal form is useful for the identification of minerals that typically show well-developed crystals.
– For many other minerals, however, the crystals grow in proximity to form a crystalline mass, in which case other mineral properties such as luster, hardness, and cleavage must be used for identification.
Fig. 3.7, p. 67
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Physical Properties of MineralsPhysical Properties of MineralsCleavage and Fracture
– Mineral cleavage refers to the breakage or splitting of mineral crystals along one or more smooth planes determined by atomic structure.
– When used with other mineral properties, cleavage can distinguish between minerals that otherwise look much the same.
– Fracture refers to the irregular breakage of a mineral Fig. 3.16, p. 79 Changing Earth 5eChanging Earth 5e Fig. 3-16, p. 79
Stepped Art
Cleavagein one direction
Cleavage plane Micas—biotiteand muscovite
Cleavage inthree directions,not at right angles
Calcite,dolomite
Cleavage insix directions
Sphalerite
Cleavage infour directions
Fluorite,diamond
Cleavage inthree directionsat right angles
Halite,galena
Cleavage intwo directionsat right angles
Potassiumfeldspars,plagioclasefeldspars
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Physical Properties of MineralsPhysical Properties of Minerals
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Physical Properties of MineralsPhysical Properties of Minerals
HardnessMohs hardness scale
– Ten minerals are used to compare the hardness between all the rest.
Table 3.2, p. 79
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Physical Properties of MineralsPhysical Properties of MineralsSpecific Gravity (Density) - The specific gravity is a way
to describe how heavy a mineral is.– Specific gravity is the ratio of the weight of a
mineral to an equal volume of water.– For example, galena has a specific gravity of 7.58 gm/cm3.
It is 7.58 times as heavy as an equal volume of water.
Fig. 3.14b-c, p. 75 Changing Earth 5eChanging Earth 5e
Physical Properties of MineralsPhysical Properties of Minerals
Other Useful Mineral Properties
– Feel - talc– Taste - halite– Magnetism - magnetite– Double refraction - calcite– React to dilute hydrochloric acid – calcite,
dolomite
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RockRock--Forming MineralsForming MineralsHow do rock-forming mineralsdiffer from accessory minerals?
– A few minerals are common enough to be known as rock-forming minerals. Most of these are silicates.
– Accessory minerals can be ignored in this endeavor because they are present in minor quantities.
Table 3.3, p. 80 Changing Earth 5eChanging Earth 5e
RockRock--Forming MineralsForming MineralsCommon rock forming minerals
Fig. 3.19, p.80
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How Do Minerals Form?How Do Minerals Form?As molten rock material known as magma (lava at the
surface) cools, minerals begin to crystallize and grow– This determines the composition of various igneous rocks.
Fig. 3.19, p. 80 Changing Earth 5eChanging Earth 5e
Natural Resources and ReservesNatural Resources and Reserves
How does a resource differ from a reserve?
– A resource is any solid, liquid, or gaseous substance in rocks whose profitable extraction is potentially feasible. Many resources are concentrations of economically important minerals.
– A reserve is only that part of the resource base that can be extracted economically.
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Natural Resources and ReservesNatural Resources and Reserves
Fig. 3.20, p. 81
– While the United States is dependent on imports for many mineral resources, Canada is more self-reliant.
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Natural Resources and ReservesNatural Resources and Reserves
What factors affect the status or a resource?
– Market price is the most obvious determinate of whether a commodity is classified as a resource or reserve
– Other factors include geographic location, labor costs, and developments in science and technology.
End of End of MineralsMinerals
Chapter 3Chapter 3