Rocks and Minerals
Study Guide
What are minerals?
• There are 5 things that characterize minerals.
– Inorganic
– Solid
– Chemical composition
– Orderly crystalline structure
– Naturally occurring
How are minerals identified?
• Hardness – how hard a mineral is relative to
another mineral
• Luster – how the surface reflects light
• Density – the amount of matter in a mineral
• Color
• Streak – the color of the powdered form of a
mineral
• Cleavage - when a mineral splits across
smooth flat surfaces
• Fracture – curved or irregular breakage
What are two ways minerals form?
• Minerals form from…
– hot molten rock (magma or lava):
When minerals from from the molten
rock, it cools and forms the mineral.
– the evaporation of hot water solutions:
When minerals form from solutions,
the solution evaporates, and leaves
the mineral behind.
Moh’s Hardness Scale
• Measures the
hardness or
scratch resistance
of minerals
What can minerals be used for?
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Jewelry, cosmetics, batteries
Hinges, clocks, wiring
Mirrors, sporting equipment, light bulbs
Watches, pencils, tiles
Appliances, matches, containers
Furniture, computers, phones
What is the rock cycle?
• The rock cycle is the
natural process in
which rocks transform
from one rock type into
another rock type over
time
What are rocks?
• A naturally occurring solid mixture of one or
more minerals that may include organic
matter
What processes change rock?
• Changing temperature and pressure
• Weathering, erosion, deposition, cementation
• Melting and cooling
How do rocks form?
• Igneous rocks form when hot liquid magma
cools into solid rock
• Metamorphic rock forms when rock is
exposed to high temperature and pressure
and the crystal structures of the minerals in
the rock change to form new minerals
• Sedimentary rock forms when rock is
weathered, eroded, deposited, buried,and
cemented
Classes and subclasses of rock
IGNEOUS
SEDIMENTARY
METAMORPHIC
Intrusive – magma that
pushes into, or intrudes
surrounding rock below
Earth’s surface and cools
very slowly forming large
crystals
Clastic – forms when
sediments are buried,
compacted, and cemented
by calcite or quartz
Foliated – forms when
pressure causes mineral
grains to align in parallel
bands
Extrusive – forms when
lava erupts and cools on
Earth’s surface quickly,
forming small crystals
Chemical – forms when
water evaporates and
chemicals crystallizes out
of the solution
Nonfoliated – no aligned
bands; made from one or
more minerals; grains or
crystals change size or
shape or into another
mineral
Organic – forms from the
remains or fossils of once
living things