Earth MaterialsMinerals: The Crystalline

State• Minerals and Mineralogy • Mineral Chemistry• Atomic Structure of Minerals• Minerals as indicators of the

environment of their formation

diamond quartz pyrite amethystasbestos

Plate boundaries and Earthquakes

Supercontinent and Plate Motion

Fig. 2.10

Supercontinent and Plate Motion

56 million years ago

Supercontinent and Plate Motion

120 million years ago

Supercontinent and Plate Motion

200 million years ago

Earth MaterialsMinerals: The Crystalline

State• Minerals and Mineralogy (p. 67-69)• Mineral Chemistry (p. 69-74)• Atomic Structure of Minerals (p. 74-

77)• Minerals as indicators of the

environment of their formation (p. 92)

diamond quartz pyrite amethystasbestos

Definition of a Mineral

• Naturally formed (inorganic)

Definition of a Mineral

• Naturally formed (inorganic)• Solid

Definition of a Mineral

• Naturally formed (inorganic)• Solid • Specific chemical composition

– What chemical elements are present and in what proportions

Definition of a Mineral

• Naturally occurring (inorganic)• Solid • Specific chemical composition• Crystal Structure

– Ordered arrangement of atoms

Definition of a Mineral

• Naturally occurring (inorganic)• Solid • Specific chemical composition• Crystal Structure

Examples: quartz (SiO2), calcite (CaCO3), halite (NaCl)

Rock is an aggregate of one or more minerals

Polished section

~1 cm

Thin Section

Thin section under ordinary light

Magnetite

Mica

Quartz

Feldspar

Thin section under polarized light

What makes each mineral unique?(p.69)• Composition

What chemical elements are present and in what proportions

– Quartz SiO2

– Olivine (Mg,Fe)2SiO3

What makes each mineral unique?(p.69)• Crystal Structure

How are the chemical elements packed together

Halite (NaCl)

Extremely soft

Extremely hardBoth minerals are made of carbon (C)

Atomic Arrangement& Physical Properties

3D framework

Sheet structure

Elements and atoms

• Chemical Elementsmost fundamental substance

separated by chemical means

• Atomssmallest particle of matterretains all properties of an element

Fig. 3.1

Structure of an Atom

• Ion an atom with excess chargecations H+

anions O2-

• Chemical Compoundelectrically neutral comb. of ions

water, H2O H+, H+, O2-

Ions and Compounds ( p. 54-56)

Complex ions

• Combination of ions with a charge

Si4+, O48- (SiO4)4- Silicate Ion

Transferring Electrons between atoms

Fig. 3.2

Ionic Bonding

Fig. 3.4

Covalent Bonds in Watersharing electrons between

atoms

Nature of Bonding and Physical Properties

3D framework

Sheet structure

Fig. 3.3 and 3.5

The Three States of Matter

Solid Liquid Gas

Ice in a glacier is a mineralWater in the oceans is not a mineral

Box B3.1

The Three States of

Water

Controlled by temperature and Pressure

low Temp, High Pressure favors solid state

In Geology, melting is a change of state

high Temp, low Pressure favors gaseous state

General Rule

Crystal Structure of Minerals (p. 74-77)

Two factors that control the arrangement of atoms and ions

Number of neighboring atoms/ions

Size of atom/ion

Galena (PbS) Packing order of

atoms

Packing arrangementPolymorphs

(p. 79)

Diamond

Graphite

Compounds that occur in more than 1 crystal arrangement

Size of ions of some

geologically important

ions

Size is based on Charge

Fig. 3.8

Silicate ion(SiO4)4-

O2-

O2- O2-

O2-

Si4+

Ionic Substitution

Olivine

Ionic Substitution

Olivine

Ions of Similar Size and Charge can substitute for each otherFor example

Ionic Substitution

OlivineMg2

2+(SiO4)4-

Ionic Substitution

OlivineFe2

2+(SiO4)4-

Fe2+-->Mg2+

Natural Olivine: (Mg,Fe)2SiO4

Phase diagram

Fig. 3.31

Minerals as indicators of their environments of their formationp. 92

Pre

ssu

re

Fig. 3.31

geotherm

Diamonds from the Mantle

Fig. 3.31

Fig. B3.1

Snowball