Chapter 5 Atoms, Elements, and
Minerals
The next few chapters in geology are mostly about
rocks. Nearly all rocks are made of minerals, so in
order to learn about rocks you need to know
something about minerals. In Chapter 5, you will
discover that:
1. Each mineral is made up of specific chemical
elements, the atoms of which are organized in a
special arrangement.
2. The chemical makeup and its internal structure
determine an element’s physical properties.
3. A mineral can be identified by its physical
characteristics, such as: cleavage, crystal form,
fracture, hardness, lustre, colour, streak, and
specific gravity.
What is Matter?
• Matter – the substance of which any
physical object is composed. Everything is
made of matter.
States of Matter:
• Solid
• Liquid
• Gas
Examples:
Controlling factors:
• Temperature
• Pressure
Gold
Mercury
Oxygen
solid
liquid
gas
The stuff that makes up all matter
• The make-up of solid matter on Earth:
Atoms  Elements  Compounds  Minerals  Rocks
(smallest)
(largest)
What is an atom?
An atom is the smallest particle of a matter
that keeps the properties of that matter.
For example, all sodium atoms are
essentially identical to all other sodium
atoms. Water (H2O) can be broken down
into two atoms of hydrogen (H) and one
atom of oxygen (O).
What are elements?
Elements are the fundamental building
blocks of matter. Elements cannot be
broken down into smaller units. Elements
are pure substances and are made of one
or more of the same type of atoms. All
elements are listed in the periodic table of
the elements.
Periodic Table of Elements
Element abundances in the crust
All others: 1.5%
What are the most abundant
elements in the Earth’s crust?
1. Oxygen (O)
-Oxygen is the most abundant element in
the crust (makes up about 50% of the
crust)
-Oxygen bonds easily with other elements
2. Silicon (Si)
-Most silicon form bonds with oxygen to
form silica
-Quartz (SiO2) is pure silica that has been
crystalized
-Any mineral that contains silica is called
a silicate
3. Aluminum (Al)
-Aluminum is more common that iron, but
difficult to separate from rocks because
it binds very tightly with oxygen.
Other elements in the Top 8 include:
Iron
Potassium
Calcium
Magnesium
Sodium
Mineral characteristics
•
Definition of a Mineral:
1.
2.
3.
4.
5.
naturally occurring
inorganic
solid
characteristic crystalline structure
definite chemical composition
QUIZ!!!
steel
no, #1
plastic
no, #1
sugar table salt
no, #1,2
YES!
basalt
no, #5
obsidian
no, #4
mica
YES!
gold
YES!
mercury ice
no, #3 YES!
paper
chalk
no, #1,2 no, #2
coal
no, #2
coral
no, #2
Mineral characteristics
•
Naturally formed
– No substance created artificially is a mineral.
examples: plastic, steel, sugar, paper
•
Inorganic
– Anything formed by a living organism and
containing organic materials is not a mineral.
examples: wood, plants, shells, coal
•
Solid
– Liquids and gases are not minerals.
examples: water, petroleum, lava, oxygen
Mineral characteristics
•
Characteristic crystalline structure
– must have an ordered arrangement of atoms
– displays repetitive geometric patterns in 3-D
glass not a mineral (no internal crystalline structure)
•
Definite chemical composition
– must have consistent chemical formula
examples: gold (Au), quartz (SiO2), orthoclase (KAlSi3O8)
basalt (like many other rocks) contains variable ratios
of different minerals; thus, has no consistent formula
How many minerals are there?
•
Nearly 4,000 types of minerals
– Only ~30 occur commonly (whew!)
– Why not more?
•
Some combinations are chemically impossible
•
Relative abundances of elements don’t allow more
Silicates
• Most minerals are silicates (which
means they contain silicon & oxygen)
• Silicates have a very special structure
called a tetrahedron. This tetrahedron
is the building block of a the silicate
crystals
Silicate tetrahedrons can combine together to make much bigger structures.
Diamond is NOT a silicate,
but pure crystallized carbon.
It is a very strong tetrahedron
(and also a mineral).
Minerals of the Earth’s Crust
The following are silicate minerals. They
are the most common minerals and
make up about 90% of the crust.
1. Feldspars
2. Quartz
3. Pyroxenes
4. Amphiboles
5. Micas
Feldspar
Amphibole
Quartz
Pyroxene
Mica
Other common mineral crystals include:
1. Clay minerals (which is another group of silicates)
2. Non-silicates
Example: gypsum
Example: calcite
1.
2.
3.
4.
5.
Halite (salt)
Diamond
Gold
Hematite & magnetite (iron)
Chalcopyrite (copper)
Physical Properties of Minerals
1.
2.
3.
4.
5.
6.
7.
8.
Colour
Streak
Lustre
Hardness
External crystal
Cleavage (most important)
Fracture
Specific gravity
Class Activity
1.Briefly explain each of the physical
properties of minerals.
Refer to Properties of Minerals
2. ID some minerals (Resource)
Video
Quiz
1. Most common element in the crust.
2. Most common mineral.
3. Which one (or ones) is/are a mineral?
Plastic quartz
salt
4. What is geology?
5. What is the topic of your geology
project?