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Lecture Outlines

PowerPoint

Chapter 2

Earth Science 11e

Tarbuck/Lutgens

Earth Science, 11e

Minerals: Building

Blocks of Rocks

Chapter 2

Minerals: the building

blocks of rocks

Definition of a mineral

• Natural

• Inorganic

• Solid

• Possess an orderly internal structure of atoms

• Have a definite chemical composition

Mineraloid - lacks an orderly internal structure

Composition and

structure of minerals

Elements

• Basic building blocks of minerals

• Over 100 are known

Atoms

• Smallest particles of matter

• Have all the characteristics of an element

Periodic table of the Elements

Figure 2.4

How atoms are constructed

Nucleus – central part of an atom that

contains

• Protons – positive electrical charges

• Neutrons – neutral electrical charges

Energy levels, or shells

• Surround nucleus

• Contain electrons – negative electrical charges

Simplified view of the atom

Figure 2.5

How atoms are constructed

Atomic number is the number of protons in

an atom's nucleus

Bonding of atoms

• Forms a compound with two or more elements

• Ions are atoms that gain or lose electrons

Isotopes

• Have varying number of neutrons

How atoms are constructed

Isotopes

• Have different mass numbers – the sum of the

neutrons plus protons

• Many isotopes are radioactive and emit energy

and particles

Minerals

Physical properties of minerals

• Crystal form

• Luster

• Color

• Streak

• Hardness

• Cleavage

The mineral quartz often

exhibits good crystal form

Pyrite (fool’s gold)

displays metallic luster

Figure 2.10

Figure 2.12

Mohs scale

of hardness

Three examples of perfect

cleavage – fluorite, halite,

and calcite

Minerals

Physical properties of minerals

• Fracture

• Specific gravity

• Other properties

• Taste

• Smell

• Elasticity

• Malleability

Conchoidal fracture

Figure 2.15

Minerals

Physical properties of minerals

• Other properties

• Feel

• Magnetism

• Double Refraction

• Reaction to hydrochloric acid

Minerals

A few dozen minerals are called the rock-forming minerals

• The eight elements that compose most rock-forming minerals are oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), and magnesium (Mg)

• Most abundant atoms in Earth's crust are oxygen (46.6% by weight) and silicon (27.7% by weight)

Composition of continental crust

Figure 2.16

Minerals

Mineral groups

• Rock-forming silicates

• Most common mineral group

• Contain the silicon-oxygen tetrahedron (molecule)

• Four oxygen atoms surrounding a much smaller

silicon atom

• Combines with other atoms to form the various

silicate structures

The silicate (SiO4)-4 molecule

Figure 2.17

Minerals

Mineral groups

• Rock-forming silicates

• Groups based upon tetrahedral arrangement

• Olivine – independent tetrahedra

• Pyroxene group – tetrahedra are arranged in

chains

• Amphibole group – tetrahedra are arranged in

double chains

Hornblende – a member of

the amphibole group

Minerals

Mineral groups

• Rock-forming silicates

• Groups based upon tetrahedral arrangement

• Micas – tetrahedra are arranged in sheets

• Two types of mica are biotite (dark) and

muscovite (light)

• Feldspars - Three-dimensional network of

tetrahedra

Minerals

Mineral groups

• Rock-forming silicates

• Groups based upon tetrahedral arrangement

• Feldspars

• Two types of feldspar are Orthoclase and

Plagioclase

• Quartz – three-dimensional network of

tetrahedra

Potassium feldspar

Plagioclase feldspar

Minerals

Mineral groups

• Rock-forming silicates

• Feldspars are the most plentiful mineral group

• Crystallize from molten material

• Nonsilicate minerals

• Major groups

• Oxides

• Sulfides

Minerals

Mineral groups

• Nonsilicate minerals

• Major groups

• Sulfates

• Carbonates

• “Native” elements

Native Copper

Minerals

Mineral groups

• Nonsilicate minerals

• Carbonates

• A major rock-forming group

• Found in the rocks limestone and marble

• Halite and gypsum are found in sedimentary rocks

• Many have economic value

Minerals

Mineral resources

• Reserves are already identified deposits

• Ores are useful metallic minerals that can be

mined at a profit

• Economic factors may change and influence a

resource

An underground halite (salt) mine

End of Chapter 2