MINERALS AND ROCKS

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CHAPTER 3 MINERALS AND ROCKS
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ELEMENTS Element- substance that cannot be broken
down by ordinary physical or chemical
reactions.      
 The two most common elements in the Earths
crust (lithosphere) are Oxygen (O, 46.6) and
Silicon (Si, 27.7).
Other major elements Al, Fe, Ca, Na, K, Mg
Elements combine to form minerals. Some are
1-element minerals Ex. Sulfur (S) Diamond
(C) Graphite (C)
 
Most are combinations of minerals. Ex.
Hematite- Fe O Halite- NaCl Dolomite- Ca
Mg C O
 
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• MINERALS
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• A mineral is
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Solid
Naturally occurring
Inorganic (Not formed from living things)
Homogeneous (uniform throughout)
Definite chemical Composition
Crystalline atoms inside are bonded in a
particular structure
The most common mineral is Quartz ( SiO2 )
Minerals combine to form Rocks
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ELEMENTS MINERALS ROCKS   A)
Silicon and Oxygen A) Silicates (most
common in crust) (most common minerals) Si
O other minerals Combine to form tetrahedron
Ex. Quartz Feldspar Mica
Hornblende
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B) Carbon ( C ) and Oxygen ( O ) B)
Carbonate Ex. Calcite, Dolomite C) Iron (
Fe ) and Oxygen ( O ) C) Iron
Oxides Ex. Magnetite D) Iron ( Fe ) and
Sulfur ( S ) D) Sulfides Ex.
Pyrite Tetrahedron  4 sided solid, each side
being a triangle    

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Bonds three ways 1.)  Single and
double chains- Breaks into slivers
Ex. Asbestos 2.)   Sheets-
Breaks into sheets Ex. Mica
3.)   3D Networks - hard, no cleavage Ex.
Quartz There are over 2400 minerals identified
on Earth! BUT only about 12 are common in most
rocks. So, How do we identify minerals?  

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PROPERTIES USED TO IDENITIFY MINERALS Minerals
are identified by their physical and chemical
properties.
A. Color A few minerals have a distinctive
color. Many minerals share the same color. Some
even have many different colors.
Malachite- Green
Sulfur- Yellow
Azurite- Blue
Pyrite- Brass
Olivine- Green
Quartz- Clear when pure,purple Green, yellow,
pink
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B. Luster the appearance of light
reflected from a minerals surface.            
?Metallic -shines like metal (Copper, Silver,
Gold)
EX Pyrite- looks like gold
? Non-metallic - does NOT look like metal.
glassy, waxy, greasy, pearly, earthy or dull.
Ex Quartz, Talc
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  C. Streak- the color of the powder of a
mineral when rubbing it against a porcelain
plate .                                        
   
The color may or may not be Ex pyrite color
streak
the same as the mineral.
brass
black
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D. Hardness- the ability of a mineral to resist
scratches. - Harder minerals will scratch softer
minerals.
-This is how you test for hardness when you have
no materials available except for the two
minerals.
-When testing for hardness you use a glass plate.
If it scratches glass its hardness is greater
than five, if it does not scratch glass its
hardness is less than five.
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Mohs Hardness Scale Ranges from 1 (softest) to
10 (hardest)
10- DIAMOND
9- CORUNDUM
8-TOPAZ
7.5 Streak Plate
7- QUARTZ
6.5 Steel File
6- FELDSPAR
5.5 Glass
5- APATITE
4.5 Iron Nail
4- FLOURITE
3.5 Copper Penny
3- CALCITE
2.5 Fingernail
2- GYPSUM
1- TALC
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  E. Crystal Structure- the shape of a
mineral.    
crystal - regular shaped solid formed by an
ordered pattern of atoms.
Mineral
Crystal Name
- Cubic
Ex. Halite
-Hexagonal (6 sides)
Ex. Quartz
- Rhombic (rectangular slant)
Ex. Calcite
- 2-dimensional (sheets)
Ex. Mica
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F. Cleavage/Fracture - the way a mineral breaks
between layers of atoms that are joined by weak
bonds.
- If a mineral breaks along a flat surface, it
has cleavage.
- If a mineral breaks or shatters with no
particular pattern it has fracture (has rough
edges.)
A minerals properties are the result of its
internal arrangement of atoms.
Ex. Cleavage atoms are line up in
rows or sheets
 Fracture atoms are connected in  all
directions
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G. Other Properties            
           
Taste-
Ex Halite (Rock Salt) tastes like salt.
Magnetism-
Ex Magnetite- is magnetic
HCl -
Ex Calcite will bubble (fizz)
Fluorescence-
Ex Glows in dark with ultraviolet light
Double Refraction-
Ex Double image of objects when light passes
through   
4) Properties of Common Minerals- See Reference
Table
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Atoms Elements Minerals
Rocks           
Rocks 3 Types of Rocks
Monomineralic Rock- Made up of 1 mineral Ex
Rock Salt (halite)
Polymineralic Rock- Made up of 2 or more
minerals Ex. Granite- quartz, feldspar, mica
1) Igneous 2) Sedimentary 3) Metamorphic
Rocks are identified
1)  How they are formed 2)  Type of minerals
they have 3)  Texture ( mineral grain size)
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5A) Igneous Rocks- forms from cooling
(solidification) of molten rock material.
2 Types
       
1)    Intrusive (Plutonic)- rocks that cooled
slowly under the ground from magma.
? Magma is molten material under the earths
surface.
? Crystals are visible (coarse (gt1mm)).
Ex Granite
? Crystals (grains) are interlocking.
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2) Extrusive (Volcanic) rocks that cooled
quickly above the ground from lava.
?Lava is magma that reached the earths surface.
? Crystals are very small or not visible.
-If crystals lt1mm, fine texture. Ex basalt
-If crystals invisible, glassy texture. Ex
obsidian -If rock has holes in it, vesicular
texture. Ex pumice
These vesicles form when bubbles of gas are in
solidified lava.
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Mafic rocks-
- High Mg and Fe concentration.
-         Dark color.
-         High density
Gabbro
Basalt
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Felsic rocks-
-         High Al concentration.
-         Light color.
- Low density.
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Cools very rapidly
Extrusive, cools quickly, no grains or lt1mm Lava
Water
Intrusive Crystals visible
Cools slowly
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5B) Sedimentary Rocks- form from compaction and
cementation of particles of sediment.
Sediment- small fragments of material.
Sediments form when rocks become broken
down into pieces by the process of
weathering.
Sediments are classified by size.
BOULDER, COBBLE, PEBBLE, SAND, SILT, CLAY
  Largest
Small
        Sediments are washed into rivers and
carried to the ocean to be dropped off or
deposited. When deposited on the ocean floor, the
sediments form horizontal layers, one on top of
the other.
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3 Types of Sedimentary Rocks
1.)Inorganic (Clastic)- came from land, not
ocean.
Name of rock depends on size of sediment
?Conglomerate-large sediment (pebbles, cobbles,
and boulders.)
?Sandstone- sand grains (visible, coarse)
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? Siltstone- silt grains (fine, gritty)
?Shale- mud, clay grains (smooth)
These sedimentary rocks are formed when overlying
sediments compress small particles that have been
deposited
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2.) Organic (Non-clastic)- made from the remains
of living things, that were deposited in water
decayed and then compressed together.
- Fossil limestone- composed of shells compressed
together.
- Coal- composed of plants compressed together.
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3.) Chemical (non-clastic)- made from chemical
evaporation and precipitation of sea water.
- Rock salt- from halite precipitating from sea
water.
- Limestone- from calcite precipitating from sea
water.
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- Dolostone- from dolomite precipitating from
sea water
- Gypsum- from gypsum precipitating from sea
water
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 Characteristics of Sedimentary Rocks
  Form horizontal layers, mostly under
water.      Only rock type that may contain
fossils. (remains of previous life)
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5C) Metamorphic Rocks- Sedimentary or Igneous
Rocks that have changed in texture or composition
due to heat and/or pressure from partial
melting.
Not enough heat to melt the rock.
Regional Metamorphism- occurs when large masses
of rock are buried and subjected to heat and
pressure. This occurs deep underground. (See
diagram.)
Contact Metamorphism- occurs when molten rock
touches existing rock, forming a narrow zone of
metamorphic rock. (See diagram.)
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2 Types of Metamorphic Rocks
1.) Foliated- have layers due to heat and
pressure.
? Mineral alignment- minerals separate to form
layers.
? Banding- alternate light and dark wavy layers.
2.) Non-foliated- NO LAYERS due to HEAT ONLY!!
? Contact metamorphism- change in the rocks
texture due to heat touching another rock.
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Characteristics of Metamorphic Rocks
1.) Distorted structure- mineral grains are bent
and crushed due to pressure.
2.) High density (Hard)
3. High resistance to weathering.
4.) Banding of minerals (foliation).
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Examples of Metamorphic Rock
Parent Rock Metamorphic Rock
Quartzite
Sandstone
Shale
Slate
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Limestone
Marble
Granite
Gneiss
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The Rock Cycle
? A model that shows the relationship between the
different types of rocks.
? MAIN IDEA Any rock can turn into any other
rock. If the right processes take place.
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7) Environments of Formation (where rocks form)
7A) Igneous Rocks
? Formed deep below Earth from cooling of magma.
Ex granite
? Formed near or above the Earths surface from
cooling of lava. Ex obsidian or basalt
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7B) Sedimentary Rocks
Found in thin layers covering most of the
continents.
? Formed just below Earths surface from
compression of sediments that were deposited from
rivers, streams, wind or ice. Ex Sandstone
? Formed in bodies of sea water from
precipitation and evaporation. Ex Rock Salt or
Gypsum
? Formed in swamps with lots of plant life. Ex
coal
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7C) Metamorphic Rocks
? Formed below the Earths surface, in areas of
extreme heat and pressure, such as where
mountains are forming.
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Textures and Characteristics
Igneous
Intrusive- see shiny crystals gt1mm, interlocking
no layers
Extrusive- crystals lt1mm or no crystals, may see
holes, may be glassy, no layers
Sedimentary
- Rock fragments (pebbles, sand, clay) compacted
together
- No Crystals
- May see layers, could see shells or fossils
Metamorphic
- Banding (layers)
- Has Crystals
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9.) Natural Resources
- Useful materials that come from the Earth.

• Many minerals and rocks are natural resources.

EX Gold, copper, oil
2 Types
1) Renewable- those that can be replaced after
use
Ex trees, freshwater
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- If renewable resources are used faster than
they are replaced scarcity
occurs.
Ex Water in SW US
2) Non-renewable those that either cannot be
replaced, or take millions of years to
replace.
Ex Metals (gold, silver) Fossil fuels
(coal, oil, natural gas)
- When these are gone society will be
adversely affected.
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10.) Alternative Energy Sources
? To replace fossil fuels
Ex solar energy (sun)
Ex Geothermal (heat inside the earth)
Ex wind
Ex nuclear