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