Download Minerals, Rocks and Resources

Minerals, Rocks and
Resources
Minerals
• Natural substances that are inorganic.
– The substance was not formed by or from living
things such as plants or animals.
• Chemical elements or compounds.
• Minerals can be identified
by their physical and
chemical properties.
– Color, Luster, Streak,
Hardness, Breakage,
Specific Gravity (Density),
Structure, and Cleavage.
Luster
• The way light is
reflected from a
cut surface of a
mineral.
– Metallic Luster
• hard, shiny
– Nonmetallic Luster
• shiny, glassy,
waxy, pearly,
earthy (dull)
Streak
• Rubbing a fresh corner of the mineral across
a white, unglazed streak plate.
• The streak is the powdered form of the
mineral.
• Some metallic minerals
leave behind a powder
that is not the same
color as the mineral.
Crystal Structure
• A regularly shaped solid formed by an
ordered pattern of atoms.
– Examples include: Six sided, cubic,
rectangular, sheets, fibers.
Hardness
• Minerals can be tested by scratching the
unknown mineral with the edge or point of
other minerals of known harness.
Mohs Scale of Hardness
Cleavage
• If a mineral breaks along
a flat surface, it shows
cleavage (to cut, or
cleave).
• Many minerals break
along cleavage planes,
sometimes parallel to
the sides of crystals.
• Those that break along
even surfaces that do
not follow the crystal
arrangement are said to
fracture.
Density
• Can be found by either dividing the mass of a
sample by its volume or flotation.
• Water’s density is 1 g/cm3
• A substance will sink in water if it is more
dense and float if it is less dense.
• Specific Gravity is a
ratio of the density of
a substance to the
density of water.
Rocks
• Nearly all rocks are
composed of one or
more minerals.
• Geologists classify rocks
according to how they were formed.
– Igneous rocks form from lava when it reaches
the surface, cools and solidifies.
– Sedimentary rocks result from the compaction
and cementing of layers of sediment.
– Metamorphic rocks form when other types of
rocks are changed by heat and/or pressure.
Igneous Rocks
• The result of the solidification
of magma or lava.
• Most lack layering, however
successive lava flows can
form a layered rock structure.
• Those that cool slowly, deep
within Earth, are composed
of large crystals.
• Those that cool faster, at or
near the Earth’s surface,
have smaller or no visible
crystals.
Igneous Rock Formation
Igneous Rock Classification
Sedimentary Rocks
• Most are composed of the weathered
remains of other rocks.
• Usually are formed by the compression and
cementing of particles
of sediment.
• Generally exist as
a thin layer over
metamorphic and
igneous rocks.
Sedimentary Rock Characteristics
• Fragmental rocks are made up of different sized
particles such as shale, sandstone and
conglomerate (composed of pebbles or larger
stones held together by natural cement).
• Organic sedimentary rock contain the accumulation
of plant and animal remains.
– Fossils are commonly found.
• Chemical sedimentary rocks are deposited by the
settling of materials from solution in seawater.
– This occurs during the evaporation of seawater and when
chemical reactions in the water form compounds that
settle.
– Rock Salt is an example.
Sedimentary
Rock
Classification
Metamorphic Rocks
• Form when sedimentary and
igneous rocks are changed by
heat and/or pressure.
• The only kind of rock that forms directly from
another rock.
• Metamorphism may cause structures, such as
layering, to become distorted or to disappear.
• It also may cause new minerals to form, and/or
crystals to grow.
• Most are formed deep within the Earth and
pushed to the surface when mountains are
formed.
Metamorphic Rock Classification
• Texture
– Appearance and feel of the rock surface
• Grain Size
• Composition
• Type of Metamorphism
Metamorphic Rock Classification
The Rock Cycle
• Natural changes in rocks and rock material that
takes place at the Earth’s surface and within Earth.
• Nearly all rocks are
made from the remains
of other rocks.
• Rocks are classified
based of their origin.
• Rocks can change in
response to changing
conditions at the surface
or within Earth.
The Rock Cycle
Natural Resources
• Substances from the Earth.
– Renewable resources can be
replaced after they have been
used.
• trees, fresh water, wind
– Nonrenewable resources
cannot be replenished after
they are used for millions of
years, if at all.
• Metals - gold, copper, iron,
Fossil Fuels – coal, oil and
natural gas
Alternative Energy Sources
• Solar energy can be used to
provide heat, hot water and
generate electricity.
– However, the amount of solar
energy that reaches Earth
varies with the time of day and
the seasons.
• Geothermal energy, heat
from within Earth, can be
used but is available only in
certain areas around the
world.
Alternative Energy Sources
• Wind-driven generators
are used in many areas to
provide electricity where
there are strong, steady
winds.
• Nuclear energy can
generate electricity without
pollution.
– However, there is a danger of a
nuclear accident and long-term
storage of radioactive wastes.