m inerals of the e arth ’ s c rust chapter 1. w hat is a mineral ? section 1 vocabulary mineral...
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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
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
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