Minerals of the Earth’s Crust
Chapter 9
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A mineral is a naturally formed, inorganic
solid that has a definite crystalline structure.
Is it a mineral?
Ask yourself these four questions.
Is it a solid?
Is it nonliving?
Does it have a crystalline structure?
Was it formed naturally?
Minerals are made up of elements.
Elements are pure substances that cannot
be broken down into simpler substances
by ordinary chemical means.
All minerals contain one or more of the 92
naturally occurring elements.
Each element is made up of only one kind of
atom.
Remember, an atom is the smallest part of an
element that has all the properties of that
element.
Meaning, the element Lithium is only made up
of lithium atoms.
Most minerals are made up of compounds
of several different elements.
A compound is a substance made of two or
more elements that have been chemically
joined, or bonded.
Example: NaCl (salt)
Formation of Crystals
Crystals are solid, geometric forms of
minerals produced by a repeating pattern
of atoms or molecules.
Every mineral has a definite crystalline
structure and can be grouped based on
their crystal formation.
Minerals are classified into two groups based
on their chemical composition.
The silicate and nonsilicate group.
Silicon and oxygen are the two most common
elements in the Earth’s crust. Minerals
that contain a combination of these two
elements are called silicate minerals.
Silicate minerals make up more than 90%
of the Earth’s crust.
Minerals that do not contain a combination of
the elements silicon and oxygen form the
nonsilicate minerals.
Some of these minerals are made up of
elements such as carbon, oxygen, fluorine,
and sulfur.
Classes of Nonsilicate Minerals:pg 227
1. Native Elements
4. Oxides
2. Carbonates
5. Sulfates
3. Halides
6. Sulfides
9.2
Identifying Minerals
There is six different properties that can be
used to identify minerals.
1. Color
2. Luster – way the surface reflects light
3. Streak – color of powder from mineral
4. Cleavage & Fracture
5. Hardness- resistance to scratching
6. Density – mass/volume
Special Properties of Some Minerals
• Fluorescence-Glow under ultraviolent
light. Example: Calcite & Fluorite
• Magnetism-Natural magnets that attract
iron. Example: Magnetite & Pyrrhotite
• Chemical Reaction-Calcite will become
bubbly from a drop of weak acid.
• Taste-Halite has a salty taste
9.3
Formation, Mining, Use of Minerals
• Minerals form in a variety of
environments in the earth’s crust.
Depending on the environment
determines the mineral’s properties.
Ore is a mineral deposit large enough and
pure enough to be mined for profit.
Mining
Surface mining-when deposits are at or
near the earths surface
Subsurface mining-when deposits are deep
within the earth
• Metallic minerals- shiny surfaces, do not
let light pass through them, and good
conductors of heat and electricity. (gold,
silver, copper)
• Nonmetallic minerals- nonmetals, shiny
or dull surfaces, may let light pass
through them, and good insulators of
electricity.(calcite, silica)
• Gemstones- are nonmetallic minerals,
and are highly valuable for their beauty
and rarity.
(diamond, ruby, sapphire, emerald,
aquamarine, topaz, and tourmaline)