Minerals of the Earth’s Crust
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Transcript of Minerals of the Earth’s Crust
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