Download Chapter 5 Minerals - Pepperell Middle School

Minerals
Simple Mineral
Properties
Rocks and minerals are not the same thing.
A mineral is a solid, naturally formed
inorganic substance that always has the
same composition and the same properties.
A mineral compares to a rock as a tree
compares to a forest. A forest is made up of
trees; most rocks are made up of minerals.
Each mineral has its own set of
properties, and it can be identified by its
properties.
Simple Physical
Properties
Color
Streak
Luster
Density
Hardness
Cleavage and Fracture
Unique Properties
Color
One of the least dependable properties
you can use to identify a mineral. Color
alone is not reliable.
Pyrite
Gold
Streak
Color of a mineral’s powder when it is
rubbed on a rough surface.
Luster
Refers to the appearance of a mineral’s
surface in light. There are two types;
metallic and non metallic
Nonmetallic luster can be described
using such terms as waxy, pearly,
glassy, dull or brilliant.
Cleavage
The way a mineral breaks: along a flat
surface
Fracture
The way a mineral breaks; along a
curved surface.
Density
A measure of how much matter, or
mass, an object contains for its size, or
volume.
Density doesn’t change with the size of
the sample.
Hardness
One of the most important properties
used to identify minerals. All minerals
fall between talc and the diamond. A
set standard is used to measure the
hardness. A German mineralogist,
Friedrich Mohs, devised the scale in
1822.
Mohs Hardness Scale
Mineral
Rating
Testing Method
Talc
1
Softest known mineral. It flakes easily when
scratched by a fingernail.
Gypsum
Calcite
2
A fingernail can easily scratch it.
3
A fingernail cannot scratch it, but a copper
penny can.
Fluorite
Apatite
Feldspar
4
A steel knife can easily scratch it.
5
A steel knife can scratch it.
6
Cannot be scratched by a steel knife, but it
can scratch window glass.
Quartz
Topaz
Corundum
Diamond
7
Can scratch steel and hard glass easily.
8
Can scratch quartz.
9
Can scratch topaz.
10
Hardest known mineral. Diamond can
scratch all other substances.
Unique Properties
Magnetism
Chemical Properties
Reaction to ultraviolet radiation.