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Geology
Mineral (definition)
1.
naturally occurring,
2.
inorganic solid
3.
with a specific chemical composition
4.
a definite crystalline structure

Minerals can form from the cooling of magma which is
the molten material found beneath Earth’s surface as
magma rises closer to the surface the molten compounds
no longer move freely and they begin to interact
chemically to form minerals
Geology
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
Minerals form by combining elements together to
create compounds. Each compound is unique and
has specific properties that separate it from other
compounds
Minerals are like rocks because all rocks are made
of minerals
Mineral Properties

Streak is easily determined by rubbing the mineral
across an unglazed porcelain plate
Mineral Properties

Streak is used to distinguish pyrite from gold
Mineral Properties

Luster is the way a mineral reflects light from its
surface and is caused by differences in mineral
chemical compositions
Mineral Properties

Either metallic or nonmetallic (dull, pearly, waxy,
silky)
Mineral Properties

Texture describes how a mineral feels to the touch
 Rough,
smooth, ragged, greasy, soapy, glassy
Mineral Properties

Hardness is a measure of how easily a mineral can
be scratched and is determined by the arrangement
of it’s atoms.
Mineral Properties

The Mohs hardness scale is used to compare a
sample to the hardness of ten known minerals
Mineral Properties

Cleavage determines whether a mineral will split
easily and evenly along one or more flat planes
Mineral Properties

Mica has perfect cleavage in one direction

Halite has cubic cleavage (3 planes)
Mineral Properties

Fracture means the mineral is tightly bonded and
breaks with rough or jagged edges

Quartz has fracture
Mineral Properties

Specific Gravity compares the weight of the mineral
to an equal volume of water at 4 degrees C
Mineral Properties

Special Properties such as light reflection and
reactions to acids are also useful tools
Mineral Properties

Calcite fizzles when in contact with HCl
Mineral Properties

Calcite also can cause double images
Mineral Properties

Magnetite will attract iron
Mineral Properties

Sulfur produces a rotten egg odor
Geology

Small crystals means
the magma cooled
rapidly

Large crystals means
the magma cooled
more slowly
Geology

Silicates are the most abundant group (96%)
containing the two most abundant elements in the
crust Silicon (Si) and Oxygen (O)
Geology

Quartz and Feldspar are the most abundant
minerals found in Earth’s crust
Geology

Carbonates are minerals composed of one or more
metallic elements with the carbonate compound CO3
( 1 atom of carbon and 3 atoms off oxygen)
Geology

Carbonates are the primary minerals in rocks such
as limestone, coquina, and marble
Limestone
Coquina
Marble
Uses for Earth Materials

Nearly every single thing we use today comes from
Earth directly or indirectly. The following is a list of
minerals and ores
Uses for Earth Materials
Name of mineral/ore Use(s)
Quartz (mineral)
Glass, watches

Uses for Earth Materials
Feldspar (mineral)
Toothpaste
Uses for Earth Materials

Calcite (mineral)
Neutralizing acids
Uses for Earth Materials
Mica (mineral)
Lampshades,
insulation, makeup
Uses for Earth Materials
Pyrite (ore)
Iron
Uses for Earth Materials

Talc
Baby powder
Uses for Earth Materials

Bauxite
Aluminum
Virginia’s Important Resources

Coal
Energy
Virginia’s Important Resources

Gravel/stone (all)
Road Construction
Virginia’s Important Resources

Limestone
Concrete
Virginia’s Important Resources

Granite
Building
materials
Virginia’s Important Resources

silica
electronics
Virginia’s Important Resources

zirconium & titanium advanced metallurgy
What are Rocks?



A rock is a naturally occurring solid
mixture of one or more minerals, or
organic matter
Rocks are classified by how they are
formed, their composition, and
texture
Rocks change over time through the
rock cycle
Igneous Rocks


Igneous rock begins as magma.
Magma can form:
 When
rock is heated
 When pressure is released
 When rock changes composition

Magma freezes between
700 °C and 1,250 °C

Magma is a mixture of
many minerals
http://www.fi.edu/fellows/payton/rocks/create/igneous.htm
Igneous Rocks

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Felsic: light colored rocks that are rich in elements
such as aluminum, potassium, silicon, and sodium
Mafic: dark colored rocks that are rich in calcium,
iron, and magnesium, poor in silicon
Coarse-grained: takes longer to cool, giving
mineral crystals more time to grow
Fine-grained: cools quickly with little to no crystals
Igneous Rocks
Coarse-Grained
Felsic
Mafic
Fine-Grained
Igneous Rocks
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Intrusive Igneous Rocks: magma
pushes into surrounding rock below
the Earth’s surface
Extrusive Rocks: forms when
magma erupts onto the Earth’s
surface (lava), cools quickly with
very small or no crystals formed
http://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&edu=high&fr=t
Igneous Rocks
Obsidian is a dark-colored volcanic glass that forms from the very rapid
cooling of molten rock material. It cools so rapidly that crystals do not form.
Sedimentary Rocks
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
Sedimentary rock is formed by erosion
Sediments are moved from
one place to another
Sediments are deposited in
layers, with the older ones
on the bottom
The layers become compacted
and cemented together
http://www.fi.edu/fellows/payton/rocks/create/sediment.htm
Sedimentary Rock

Sedimentary Rocks are formed at or near the
Earth’s surface

No heat and pressure involved

Strata – layers of rock

Stratification – the process in
which sedimentary rocks are
arranged in layers
Sedimentary Rock
Clastic – made of fragments of rock
cemented together with calcite or quartz
Sedimentary Rock
Chemical sedimentary – minerals crystallize
out of solution to become rock
Rock Salt is a chemical sedimentary rock
that forms from the evaporation of ocean
or saline lake waters. It is also known by
the mineral name "halite". It is rarely
found at Earth's surface, except in areas
of very arid climate. It is often mined for
use in the chemical industry or for use as a
winter highway treatment. Some halite is
processed for use as a seasoning for food.
The specimen shown above is about two
inches (five centimeters) across.
Sedimentary Rock
Organic sedimentary – remains of
plants and animals
Sedimentary Rock
Organic sedimentary – remains of plants and
animals
Metamorphic Rock
 Meaning to change shape
 Changes with temperature
and pressure, but remains
solid
 Usually takes place deep in
the Earth
http://www.fi.edu/fellows/payton/rocks/create/metamorph.htm
Metamorphic Rocks
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Contact Metamorphism – heated by nearby magma
Increased temperature changes the composition of the
rock, minerals are changed into new minerals
http://www.windows.ucar.edu/tour/link=/earth/geology/meta_contact.html&edu=h igh&fr=t
Metamorphic Rocks
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Regional Metamorphism – pressure
builds up in rocks that is deep
within the Earth
Large pieces of the Earth’s crust
collide and the rock is deformed
and chemically changed by heat
and pressure
http://www.windows.ucar.edu/tour/link=/earth/geology/meta_regional.html&edu=high&fr=t
Metamorphic Rock

Foliated - contain aligned grains of flat minerals
Metamorphic Rock

Non-Foliated – mineral grains are not arranged in
plains or bands
Metamorphic Rock

Determine if the following rock samples are foliated
or non-foliated:
Amphibolite
Quartzite
Phyllite