Introduction to minerals

Earth Materials:
Minerals


Today’s Lecture: Chapter 5. Patterns in
Nature: Minerals

1. Minerals: Why care?
2. Atoms, ions &
isotopes of the elements
3. Atomic bonding and
the formation of
chemical compounds
4. Minerals: the
building blocks of rocks
Internal structure in
relationship to physical
properties
5. Introduction to
rocks.


Minerals: Why care?
Raw materials for nearly all of the
manufactured products we use are obtained
from minerals.
Examples:
➨ Aluminum: Soft drink cans
➨ Graphite (Carbon): Pencil lead and lubricant
➨ Copper: Electrical components and wire
➨ Talc: Baby powder

➨ Silver, gold, gemstones: Jewelry
➨ Silicon: Computer chips


Malachite: Ore of copper and a gemstone.


Quartz: Source of silicon used
in making computer chips


Galena: Ore of lead


Gemstones!


Minerals: Why Care?
Other reasons:

➨ Rocks inform us about geologic hazards, such
as volcanic eruptions, earthquakes etc.,
enabling us to make better decisions about how
we interact with the Earth and use its resources
(e.g. siting and designing buildings).
➨ Rocks hold important clues for understanding
processes of weathering and erosion. This
information can help us use the Earth’s
resources more effectively (e.g. extraction of
mineral and petroleum resources, soil

conservation, degradation of concrete
structures, etc.).
➨ Rocks enable us to understand our past &
place our lives in proper evolutionary context.


Understanding Matter…

To understand minerals we need to
understand matter and how it is
organized.
The three states of matter:
▼ Solid
▼ Liquid
▼ Gas


States of Matter
Solids-Atoms and molecules organized into fixed
structures with a defined shape (crystals, glass,
plastics). Atoms move (vibrate) even in a solid! Just
limited in a solid.
Liquids-Fluid mixtures of atoms and molecules
existing as charged atoms or molecules (e.g. “ions”).
Atoms in solutions can form loose associations with
each through transient electronic “bonds”. However,
the liquid lacks a fixed structure, like that seen in
most solids.
Gases-Fluids in which atoms and molecules are in
rapid motion, freely moving about with no fixed

structure. Gases expand to fill the available space.


Bulding blocks of minerals
Atoms, elements
and compounds:
Building blocks of minerals
(See Science Toolbox 5.1, page 112 of text)

•Elements: Different types of atoms that, in their
pure form, cannot be divided into other smaller
units without changing their properties.

•Atom: Smallest division of an element,

that still possesses the chemical properties unique
to the element.

•Compounds: Two or more atoms bonded

together. May be composed of atoms of the same
element, or combinations of several different
elements.


Understanding Matter…

What is an atom?
An atom is made up of:
-A nucleus: Central region of atom where most of

the mass resides. Comprised of protons and neutrons.
-Orbiting electrons: High-speed nearly “massless”
particles of negative charge which orbit the nucleus.
electrons
nucleus


Understanding Matter…

Nucleus contains:
Protons

= Particles with a mass of 1.0 and a
positive electrical charge.
Neutrons = “
“
a mass of 1.0 and a
neutral electrical charge. Neutrons may
be thought of as a proton bound to an
electron.
A single
atom

ons
r
t
u
ne

protons

electrons

Orbiting the
nucleus are
electrons having
essentially no
mass ands a
negative charge.


Understanding Matter…

A simple “ Bohr” model for a single atom:

T&L: Figure 2.4 A


Structure of an Atom

...in reality

Nucleus of protons
and neutrons

T&L: Figure 2.4 B


Types of Atoms and Elements

Number of protons in the
nucleus of an element is called
Its atomic number.

Model of
one atom

nucleus

Elements are distinguished from
each other by their atomic
number.

Examples: All Helium atoms have 2 protons

“ Carbon “
“ Uranium “

“ 6
“ 92

“
“


Isotopes: Same element, different mass

Mass Variations in Elements:
● The number of protons plus the number of neutrons

in the nucleus defines the atomic mass of the element.
●However, most elements come in different “species”versions that differ slightly in mass because of having
different numbers of neutrons in the nucleus.
●These “species”of elements are called isotopes.


Isotopes: Atoms that vary in the number of neutrons in the nucleus

Again… mass variations of the same element are
called “isotopes”.
Many isotopes are unstable, and disintegrate
through a process called radioactive decay
where particles and/or energy are emitted
from the nucleus
Example: Carbon-14

14

C

is unstable

The rate of radioactive disintegration is constant, so
they can be used as a kind of clock for dating rocks!


Classifying the Elements
Let’s review using Carbon as an example:
●Number of protons determines the type of atom

6 protons = carbon
● Number of neutrons in an atom can vary.
● Number of neutrons plus the number of protons equals the
atomic “mass”.
How we write it
●Here are the three isotopes of Carbon:
6 protons & 6 neutrons: mass number = 12 C
6 protons & 7 neutrons: mass number = 13 C
6 protons & 8 neutrons: mass number = 14 C
12
13

14


Elements are classified by the number of protons
in the nucleus (I.e., their atomic number)
Periodic table of the elements
equals # of protons

6 => 6 protons


Classifying the Elelemnts

112 known elements
Only 92 occur
naturally

Classifying the Elements
You’ve heard of many of these elements, for example:
Helium

Hydrogen
Oxygen
Aluminum
Iron
Calcium

Titanium

Gold


Ions: Charged Atoms
Atoms that lose or gain electrons develop a charge.

When atoms give away or gain electrons, they
are no longer electrically neutral. In other words,
They take on an electrical charge.
Any atom possessing a charge is called an “ion”.
Atoms with a positive charge are called “cations”.
Those with a negative charge are called “anions”.


Making Minerals

~ 4000 minerals on Earth!

● Different elements combine to make chemical

compounds…
Example 1: water (2 hydrogen atoms + 1 oxygen atom = H2O)

Example 2: salt (1 sodium atom + 1 chlorine atom = NaCl)

Minerals are naturally-occurring
compounds that are classified by their:
◆ Chemical composition
◆ Internal (“atomic”) structure


Example: Quartz

Quartz contains:
silicon (Si) and
oxygen (O)
element
name

Chemical formula for quartz is: SiO2

symbol