…the same type of mineral! They are examples of
quartz!!
 There are over 3000 types of minerals in the Earth’s
crust
 As you could see with the quartz, often times even the
same kind of minerals can look very different
 Therefore, geologists (scientists who study minerals
and rocks) often use several different tests to
determine type of a mineral they have found!
 Color is obviously one of the most noticeable
characteristics of a mineral, but it also the least
reliable of all the characteristics
 The color of a mineral is often caused by tiny amounts
of other elements or compounds inside
 For example, what people call amethyst is actually just
quartz with iron in it!
 The way that a mineral reflects light from its surface is
its luster
 The two types of luster are:
- metallic
- nonmetallic
Metallic Luster
 Texture describes how a mineral feels to the touch.
 Minerals can range anywhere between glassy feeling,
rough feeling, greasy feeling, and even soapy feeling!
Talc has a soapy texture.
Fluorite has a
glassy texture.
 When a mineral is rubbed
against a tile, it will leave
behind a colored powdered
streak on the tile
 Sometimes a mineral’s
streak does not match the
mineral’s external color
 For example, one way to tell
the difference between
pyrite (Fool’s gold) and real
gold is by streak. Pyrite
leaves a greenish-black
streak while real gold leaves
a yellow streak.
Hardness
 Hardness is a
measure of
how easily a
mineral can
be scratched
 Geologists
use Mohs
scale to give
minerals
their
hardness
ratings
Mineral
Associations and Uses
1
Talc
Talcum powder.
2
Gypsum
Plaster of paris. Gypsum is formed when seawater evaporates from the
Earth’s surface.
3
Calcite
Limestone and most shells contain calcite.
4
Fluorite
Fluorine in fluorite prevents tooth decay.
5
Apatite
When you are hungry you have a big "appetite".
6
Orthoclase
Orthoclase is a feldspar, and in German, "feld" means "field".
7
Quartz
8
Topaz
The November birthstone. Emerald and aquamarine are varieties of beryl
with a hardness of 8.
9
Corundum
Sapphire and ruby are varieties of corundum. Twice as hard as topaz.
10
Diamond
Used in jewelry and cutting tools. Four times as hard as corundum.
 The pattern of atoms will determine how a mineral
will break
 A mineral that breaks relatively easily and evenly at
angles is said to have cleavage
 Minerals that break with rough or jagged edges are
said to have fracture
 Some minerals have unique properties
 For example, Iceland spar can create double images
 Some minerals react with hydrochloric acid and
releases carbon dioxide (bubbles)