Earth Materials
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Transcript Earth Materials
MINERALS
Chemical
composition of the
Crust
Oxygen most abundant- 46.6%
Followed by silicon and
aluminum
Iron, Calcium, Sodium,
Potassium, Magnesium
The most common minerals
will be composed mostly of
these elements
Silica & silicates
MINERAL vs. ROCK
ROCK
An
aggregate of one or more MINERALS
(usually- coal, organic)
MINERAL
Solid
Crystalline-
orderly arrangement of atoms
Naturally occurring
Inorganic
Definite chemical composition
e.g.
SiO2 for quartz; KAlSi3O8 for
feldspar
Atom & Elements
Atoms
Neutral
Nucleus
Proton,
Electron
Ions
Electrical
neutron
Charge
Molecule- e.g. water molecule
Chemical activity
Stable atoms want
positive
& negative charges balanced
electron shells full
Ions- positive (Cations) and negative (Anions)
Bonding
Ionic
Covalent
Metallic
Van
der Waal’s
Element
Atomic number
Number
of PROTONS
Isotope
Differing
number of
NEUTRONS
Atomic weight
Mass
of PROTONS and
NEUTRONS
Crystallinity
3 dimensional orderliness of atoms
Silicon-oxygen tetrahedron
Silicate structures
Single-
e.g. olivine
Chain
Single
chain- pyroxene
Double chain- amphibole
Sheet-
e.g. mica, clay
Framework- e.g. quartz, feldspar
MINERALS
Crystalline solids
Natural and Inorganic Substances
Definite chemical composition
Can
be written as a chemical
formula
Solid solution (within a range)
Important Minerals
Quartz (most abundant)
FELDSPAR Group
Potassium
Feldspar - Orthoclase
Plagioclase Feldspar
Sodium
(Na) Albite
Calcium (Ca) Anorthosite
Important Minerals
PYROXENE Group- Augite most
common
AMPHIBOLE Group- Hornblende
most common
MICA Group- Si + O in sheets
Biotite
Muscovite
CALCITE- CaCO3
Properties of Minerals
Color
Not
always reliable (Olivine, green; Flourite,
yellow, purple, green…)
Ferromagnesian minerals green or black
Streak- powdered form
Luster- reflectance of light
Metallic
Nonmetallic
Vitreous
Earthy
or Glassy
Properties of
Minerals
Hardness- resistance to scratching
Moh’s Hardness Scale
Fingernail
= 2.5
Penny = 3.5
Knife/Glass = 5.5
Streak Plate= 6.5
Cleavage
Properties of
Minerals
Quality
(poor, good, perfect)
Number of directions
One-
e.g. Mica
Two at right angles- e.g. Feldspar, Pyroxene
Two not at right angles- e.g. Amphibole
Three at right angles (cubic)- e.g. Halite
Three not at right angles (rhombohedral)- e.g.
calcite
Four (Flourite) or six (Sphalerite)- not common
Properties of
Minerals
Fracture
Absence
of cleavage
Irregular fracture
Conchoidal fracture- Quartz
Density
Specific
Gravity
Some unusual properties
Striations,
refraction
Magnetism, Taste, Odor, Double
Chemical tests
Reaction with HCl
Calcite
effervesces
Mineral Groups
Silicates
Carbonates
Oxides
Sulfides
Sulfates
Native Elements
Halides
Silicates
Quartz
Feldspar
Plagioclase
Orthoclase
Micas
Muscovite
Biotite
Amphibole (Hornblende)
Pyroxene (Augite)
Olivine
Carbonates
Calcite (calcium carbonate)
Dolomite (calcium-magnesium
carbonate)
Both are used as Portland Cement
Oxides
Hematite (iron oxide)
Iron
Magnetite
Iron
ore, pigment
ore
Corundum (aluminum oxide)
Sapphire,
Abrasive
ruby (gemstone)
Sulfides
Galena (Lead sulfide)
Lead
Sphalerite Zinc sulfide)
Zinc
ore
ore
Pyrite (Iron sulfide)
Sulfuric
acid
Chalcopyrite (Copper Iron sulfide)
Copper
ore
Sulfates
Gypsum
Anhydrite
Both use in plaster
Native Elements
Gold- trade, instruments
Silver- photography, conductors
Copper- electrical
Platinum- catalysts
Sulfur- chemicals, pharmaceuticals
Diamond- carbon
Gemstone, abrasive
Graphite- carbon
Lubricant, pencils
ROCK CYCLE
Equilibrium
Interrelationships between
igneous
rocks
sediment
sedimentary rocks
metamorphic rocks
weathering and erosion
Rocks
Classification of Igneous,
Sedimentary and Metamorphic
Rocks
IGNEOUS ROCKS
EXTRUSIVE
Volcanic- Fine-grained
INTRUSIVE
Plutonic- Coarse-grained
MAGMA
Molten Rock
Usually with dissolved gasses
Generated at depth
Eruptions if magma (lava) reaches surface
If doesn’t reach surface, Solidifies underground
Intrudes country or host rock
Intrusive contact
Xenolith- ‘foreign body’
Igneous Rocks
Names based on mineral
composition reflects chemical
composition of the magma and...
Grain size
Very
coarse-grained Pegmatitic
Coarse-grained: Phaneritic > 1
mm.
Fine-grained: Aphanitic < 1 mm.
Porphyritic- 2 crystal sizes
Igneous RocksClassification
Coarse-grainedPlutonic (Intrusive)
Granite (Sialic) (SIlica and ALuminum rich)
Diorite
Gabbro (Mafic) (MAgnesium and iron (FE) rich)
Dunite & Peridotite (Ultramafic)
Fine-Grained
Volcanic (Extrusive)
Rhyolite (Sialic)
Andesite
Basalt (Mafic)
Igneous Rock Identification
Granite (& Rhyolite)
High in Si + O
Low in Fe + Mg
Mostly feldspar &
quartz
Light-colored
Basalt (& Gabbro)
“Low” in Si + O
High in Fe + Mg
no quartz, abundant ferromagnesian minerals
Dark colored
Andesite (& Diorite- intermediate)
COARSE-GRAINED
PLUTONIC ROCK
GRANITE
WEATHERING, EROSION,
TRANSPORTATION
Weathering- Physical disintegration and
chemical decomposition of rocks
Erosion- Physical removal
Transportation- Movement of eroded particles
Chemical vs. Physical Weathering
Physical Weathering
ROCK CYCLE
Relative Percentages of
Sedimentary Rocks
SEDIMENT
Particle size
Pebbles,
cobbles, boulders
Gravel- > 2mm
Sand- 2mm - 0.063mm
Silt - 0.063mm - 0.004mm
Clay- < 0.004
Deposition
Clay-sized particle vs.
clay mineral
TYPES OF
SEDIMENTARY ROCKS
Clastic or Detrital
Chemical- inorganic
precipitation or evaporation
Biochemical- Organic remains
shells,
charcoal, plant fragments
CLASTIC (Detrital)
ROCKS
Breccia and Conglomerate (>
2mm)
Sedimentary
Breccia- angular
fragments
Conglomerate- rounded fragments
Sandstone (2mm - 0.063mm)
Quartz
sandstone
Arkose (feldspar)
Graywacke (appreciable amounts
of silt/clay)
Fine-grained
Matrix
Quartz Sandstone
CHEMICAL
SEDIMENTARY ROCKS
Carbonate Rocks
Limestone Inorganic
made of calcite
varieties
• micrite, oolites, travertine
Dolomite
Recrystallization
Chert- silica
Evaporites
Rock
gypsum
Rock salt
MICRITE
OOLITES
Chert
BIOCHEMICAL SEDIMENTARY
ROCKS
Coal
Develops
plant
from peat
fragments
Lignite
Bituminous
Coal
Carbonate Rocks
Limestone organic
made of calcite
varieties
• Coquina
• Fossiliferous Limestone
• Chalk
Metamorphic Rocks
Metamorphism
Increase in Pressure; increase in Temperature
Burial
Contact
Regional
Metamorphic rock
Pre-existing rock
Parent rock
Foliation
Classification
A- Slate
C- Phyllite
D- Schist
E- Gneiss
F- Migmatite
Classification