Earth Science
Chapter 2
Section 1
A. What is a Mineral:
A mineral is a naturally occurring, inorganic solid that has a
crystal structure and a definite chemical composition.
1. Naturally Occurring – Not man-made.
2. Inorganic – A material that was never living.
3. Solid – A material that has a definite shape and volume,
particles are not free flowing
4. Crystal Structure – Particles of a crystal line up in a
pattern that repeats over and over. The repeating pattern
of a solid forms a crystal. A crystal has flat sides called
faces and sharp edges called corners.
5. Definite Chemical Composition - A mineral always
contains elements in definite proportions, it never
varies.
1. Element - a substance made up of a single kind
of atom.
2. Compounds – two or more elements combined
so that the elements no longer have distinct
properties.
B. Identifying Minerals:
Each mineral has its own specific properties that can be used to
identify it.
Properties of a Mineral:
1. Hardness – One of the identifying factors of a mineral is
how hard it is. A scale has been devised to identify the
hardness of a mineral.
a. Mohs hardness scale – This scale ranks minerals
from softest to hardest.
2. Color – The color of a mineral is a physical property that
can be used , but can only be used when the color of a
mineral never changes. Many mineral colors change due
to impurities in the compound.
3. Streak - The color of a minerals powder.
4. Luster – How a mineral reflects light from its surface.
Luster can be identified as metallic, glassy, earthy, waxy
and pearly.
5. Density – The mass is a given space or the mass per unit
volume. No matter the size of a mineral the density
remains the same.
6. Crystal System - Property based on the number of crystal
faces.
7. Cleavage and Fracture – The way the mineral breaks apart.
a. A mineral that splits along flat plains has cleavage
b. A mineral that breaks apart in an irregular pattern.
For Example: Quartz – Shell-like break
Copper and Iron- hackly, From jagged points, soft
minerals crumble like clay.
8. Special Properties –
a. Fluorescence- Glow under UV light.
b. Magnetic – natural magnets - Magnetite
c. Radioactive – Give off radiation –Uraninite
d. React to Acid – Calcite fizzes and gives off carbon
dioxide.
e. Electrical properties- Quartz gives off electrical
charges when under pressure.