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What is a Mineral
Chapter 3 Minerals of Earth’s
Crust
Mineral
• A naturally formed, inorganic solid that has
a definite crystalline structure
Questions to ask yourself
• Is it a nonliving material?
– A mineral is inorganic, meaning it isn’t made of living things
• Is it a solid
– Minerals cant be gases or liquids
• Does it have a crystalline structure
– Minerals are crystals, which have a repeating inner structure that
is often reflected in the shape of a crystal. Minerals generally
have the same chemical composition throughout
• Is it formed in nature?
– Crystalline materials made by people aren’t classified as
minerals.
What is an
• Pure substance that cannot be broken
down.
What is a Compound made of?
• Compound- a substance made of TWO or
more elements that have been
CHEMICALLY combined.
– Ex: Halite (NaCl)
Crystals
• A solid whose atoms, ions, or
molecules are arranged in a definite
pattern
– Geometric forms of minerals produced by
a repeating pattern of atoms
– Shape is determined by arrangement of
atoms
Two Groups of Minerals
• Most common classification of minerals is
based on chemical composition.
– Silicate Minerals
– Nonsilicate Minerals
Silicate Minerals
• Minerals that contain a combination
of silicon and oxygen as well as
other elements.
• Make up more than 90% of the
Earth’s crust
• Other common elements they
combine with include: aluminum,
iron, magnesium and potassium.
Common Silicate Minerals
Feldspar
Quartz
Mica
Nonsilicate Minerals
• Minerals that do not contain a combination of the
elements silicon and oxygen.
• Some include carbon, oxygen, fluorine, and
sulfur.
• Classes of nonsilicate minerals:
–
–
–
–
–
–
Native Elements
Carbonates
Halides
Oxides
Sulfates
Sulfides
Halite
Galena
Spinel
Pyrite
Gypsum
Calcite
Hematite
Native Elements
• Minerals composed of only one element
– Ex: copper, gold, silver
– Used in communications and electronic
equipment
Carbonates
• Minerals that contain combinations of
carbon and oxygen in their chemical
structure.
• Used in cement, building stones and
fireworks
Halides
• Compounds that form when fluorine,
chlorine, iodine, or bromine combine with
sodium potassium or calcium.
• Used in the chemical industry and in
detergents
Oxides
• Compounds that form when an
element such as aluminum or iron
combines chemically with oxygen.
• Used to make abrasives, aircraft
parts and paint
Sulfates
• Minerals that contain
sulfur and oxygen
• Used in cosmetics,
toothpaste, cement, and
paint.
Sulfides
• Minerals that contain one
or more elements, such
as lead, iron or nickel,
combined with sulfur.
• Used to make batteries,
medicines, and electronic
parts.
Assignment
• Section Review Chapter 3 Section 1
Identifying Minerals
• We use several different properties to help
identify minerals
– Color
– Luster
– Streak
– Cleavage and Fracture
– Hardness
– Density
– Special Properties
Color
• The same
mineral can often
come in a variety
of colors
• Not the best way
to identify a
mineral
All 3 are Pyrite
(fools gold)
Luster
• The way a surface reflects light
• Minerals have metallic, submetallic or
nonmetallic luster
– Shiny = metallic
– Dull = submetallic or nonmetallic
Types of Mineral Luster
Bright and Reflective
Dull and Plastic
Dull and Reflective
Streak
• Color of a mineral in powdered form
• Found by rubbing the mineral against a
piece of unglazed porcelain called a streak
plate
• The color of the mineral’s streak is not
always the same as the color of the
mineral sample
• Good way to identify a mineral
Different types of minerals break in different ways.
The way a mineral breaks is determined by the
arrangement of its atoms.
Cleavage
• The splitting of
a mineral
along smooth,
flat surfaces.
Fracture
The manner in
which a mineral
breaks along either
curved or irregular
surfaces
Hardness
• A minerals resistance to being scratched
• We use Mohhs Hardness scale to
determine the hardness
• To identify a mineral scratch the surface of
a mineral with the edge of one of the 10
reference minerals.
• If it scratches the reference mineral your
mineral is harder
Mohs Hardnes Scale
Density
• Measure of how much matter is in a given
object
• Ratio of an objects mass to it’s volume
• Measured in grams per cubic centimeter
• Water is used as a reference because we
know it has a density of 1g/cm3
Special Properties
• Some properties are particular to only a
few types of minerals.
Assignment
• Section Review 3-2 page 73 #1-8