MINERALS OF THE EARTH’S CRUSTChapter 1

WHAT IS A MINERAL?

Section 1 Vocabulary Mineral Element Compound Crystal Silicate Mineral Nonsilicate Mineral

THE FOUR ESSENTIAL QUESTIONS

Is it nonliving material?

Is it a solid? Does it have a

crystalline structure?

Is it formed in nature?

MINERAL STRUCTURE

Four questions Needs to be a yes

for all 4 Crystalline Structure

Need to know about elements

Elements All minerals contain

one or more 92 naturally

occuring elements

ATOMS AND COMPOUNDS

One kind of element Atom-smallest part of

an element that has all the properties of that element

Compound Halite-NaCl

Compound Na-Sodium Cl-Chlorine

One Element Gold or Silver Native element

CRYSTALS

Shape-by the arrangement of the atoms within the crystal

Arrangement-by the kinds of atoms that make up the mineral

Definite crystalline structure

Crystal Classes

TWO GROUPS OF MINERALS

Most common classification of minerals is based on chemical composition Silicate minerals Nonsilicate minerals

SILICATE MINERALS Silicon and oxygen

Two most common elements in the Earth’s crust

Combination 90% Combine with other

elements

NONSILICATE MINERALS

Do not contain silicon and oxygen

Most important classes Native elements Carbonates Halides Oxides Sulfates Sulfides

IDENTIFYING MINERALS

Section 2 Vocabulary Luster Streak Cleavage Fracture Hardness Density

COLOR

Same mineral-variety of colors Quartz Granite

Change of color Impurities Other factors

Air Water

NOT THE BEST WAY TO IDENTIFY A MINERAL

LUSTER

The way a surface reflects light

Shiny or dull Metallic-Shiny,

bright, and reflective Submetallic-dull and

reflective Nonmetallic-dull and

not reflective Figure 1

STREAK

The color of a mineral in powered form

Streak Plate-a mineral’s streak can be found by rubbing the mineral against a piece of unglazed porcelain

Color is not always the same

Not affected by air or water

MORE RELIABLE THAN COLOR

CLEAVAGE AND FRACTURE

The way a mineral breaks is determined by the arrangement of its atoms.

Cleavage-break smooth

Fracture-uneven break

HARDNESS

A mineral’s resistance to being scratched

MOHS HARDNESS SCALE

Talc-1 Diamond-10 The greater a

mineral’s resistance to being scratched is, the higher the mineral’s rating is.

Scratch it on another rock

DENSITY

The measure of how much matter is in a given amount of space.

Density=Mass/Volume

Grams per cubic centimeter (g/cm3)

Water is used as a reference point. 1 g/cm3

Specific Gravity

SPECIAL PROPERTIES

Only a few minerals! Fluorescence-glow

under ultraviolet light Magnetism-attract

iron Chemical Reaction-

acid will cause a fizz Taste-halite-salty Optical Properties-

double image Radioactivity- radium

or uranium

THE FORMATION MINING AND USE OF MINERALS

Section 3 Vocabulary Ore Reclamation

MINING

Must be mined to extract valuable elements

To describe a mineral deposit large enough and pure enough to be mined for profit

Two Forms Surface Mining Subsurface Mining Depends on Location

SURFACE MINING At or Near the Surface

Open pits- remove large, near-surface deposits of economically important minerals Gold/silver Downward layer by layer Explosives

Surface Coal Mines-strip mining-moved in strips

Quarries-used for mining building stone, crushed rock, sand, and gravel

SUBSURFACE MINING

Too deep within the Earth to be surface mined

Passageways Horizontally At an angle

If deep in the earth a vertical shaft is sunk Connects

passageways at different levels

RESPONSIBLE MINING

Return the land to its original state after the mining is complete

Law since mid-1970’s

Reduce needs for minerals

Recycling

METALLIC MINERALS

Shiny Surfaces Does not let light

pass through them Conductors of heat

and electricity Strong, Do not Rust Gold, Silver, and

Copper

NONMETALLIC

Shiny or dull surfaces

May let light pass through them

Good insulators of electricity

Most Widely used Calcite and Silica

GEMSTONES

Highly Valuable Diamond, Ruby,

Sapphire, etc. Color is most

important More attractive the

more value Durable Carat