Transcript Minerals of the Earth*s Crust

MINERALS OF THE EARTH’S
CRUST
Chapter 1
WHAT IS A MINERAL?
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Section 1 Vocabulary
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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?
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MINERAL STRUCTURE
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Four questions
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Crystalline Structure
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Needs to be a yes for
all 4
Need to know about
elements
Elements
All minerals contain
one or more
 92 naturally occuring
elements
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ATOMS AND COMPOUNDS
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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
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One Element
Gold or Silver
 Native element
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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
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TWO GROUPS OF MINERALS
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Most common
classification of
minerals is based on
chemical composition
Silicate minerals
 Nonsilicate minerals
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SILICATE MINERALS
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Silicon and oxygen
Two most common
elements in the
Earth’s crust
 Combination
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90%
 Combine with other
elements
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NONSILICATE MINERALS
Do not contain silicon
and oxygen
 Most important
classes
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Native elements
Carbonates
Halides
Oxides
Sulfates
Sulfides
IDENTIFYING MINERALS
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Section 2 Vocabulary
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Luster
Streak
Cleavage
Fracture
Hardness
Density
COLOR
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Same mineral-variety
of colors
Quartz
 Granite
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Change of color
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Impurities
Other factors
Air
 Water
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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
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STREAK
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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
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HARDNESS
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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.
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1 g/cm3
Specific Gravity
SPECIAL PROPERTIES
Only a few minerals!
 Fluorescence-glow
under ultraviolet light
 Magnetism-attract
iron
 Chemical Reactionacid will cause a fizz
 Taste-halite-salty
 Optical Propertiesdouble image
 Radioactivity- radium
or uranium
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THE FORMATION MINING AND USE OF
MINERALS
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Section 3 Vocabulary
Ore
 Reclamation
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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
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Surface Mining
 Subsurface Mining
 Depends on Location
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SURFACE MINING
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At or Near the Surface
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Open pits- remove large,
near-surface deposits of
economically important
minerals
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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
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SUBSURFACE MINING
Too deep within the
Earth to be surface
mined
 Passageways
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Horizontally
 At an angle
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If deep in the earth a
vertical shaft is sunk
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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
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METALLIC MINERALS
Shiny Surfaces
 Does not let light pass
through them
 Conductors of heat
and electricity
 Strong, Do not Rust
 Gold, Silver, and
Copper
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NONMETALLIC
Shiny or dull surfaces
 May let light pass
through them
 Good insulators of
electricity
 Most Widely used
 Calcite and Silica
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GEMSTONES
Highly Valuable
 Diamond, Ruby,
Sapphire, etc.
 Color is most
important
 More attractive the
more value
 Durable
 Carat
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