What is a Mineral?

Naturally-formed solid substance with a
crystal structure
Pyromorphite
What do all minerals have in
common?
All:
1.
2.
3.
4.
5.
Are formed by natural processes.
Are NOT alive and NEVER were alive
Have a definite volume and shape
Are elements or compounds with a unique
chemical makeup
Are made up of particles that are arranged in
a pattern that is repeated over and over
(called a CRYSTAL)
Groups of Minerals

Minerals are grouped by the elements
they are made of.
Beryl (Emerald)
Calcite
Amethyst
Mineral Group
Characteristics
Contain
Silicates
oxygen & silica
The most
abundant group
of minerals
MICA
Examples
Quartz, mica
Quartz
Mineral Group
Characteristics
Make
Non-Silicates
Silver
up only
5% of the
Earth’s crust
Include some
of the most
important
minerals
Examples
iron, copper,
gold, silver,
diamonds,
rubies
Copper
Diamond
Gold
Ruby
Iron
Mineral Group
Carbonates
Characteristics
Carbon
Examples
&
Calcite (CaCO3)
oxygen and a
positive ion,
such as calcium
Calcite with Duftite inclusions
Mineral Group
Oxides
Characteristics
Metallic
ion
and oxygen
Examples
Hematite
(Fe2)O3
Mineral Group
Sulfides
Characteristics
Sulfur
and a
metallic ion
Examples
Galena (PbS)
Mineral Group
Sulfates
Barite on Calcite
BaSo4 / CaCO3
Characteristics
Metallic
Sulfur &
oxygen
ion,
Barite
BaSo4
Examples
Barite (BaSO4)
Mineral Group
Native
Elements
Characteristics
Single
elements
Examples
Gold (Au),
Diamond (C),
Silver (Ag)
How do minerals form?

1) Cooling of magma (hot, liquid rock and
minerals inside the earth (from the
mantle))



Fast Cooling = No Crystals (mineraloids)
Medium Cooling = small crystals
Slow Cooling = large crystals
How do minerals form?

2) Elements dissolved in liquids (usually
water)
Physical Properties of Minerals
(can be used to identify the mineral)
Color
 Can be misleading
 Can vary with the type of impurities
Physical Properties of Minerals
(can be used to identify the mineral)
Luster
 Surface reflection
 metallic = shiny like
metal
 non-metallic = dull,
non-shiny surface
Pyrite has a metallic luster
Calcite has a non-metallic luster
Physical Properties of Minerals
(can be used to identify the mineral)
Streak
 The color of the powdered
form of the mineral
 The color of the streak can be
different than the mineral
 Minerals must be softer than
the streak plate
Streak…can help identify quartz
http://www.childrensmuseum.org/geomysteries/cube/b3.html
Physical Properties of Minerals
(can be used to identify the mineral)
Hardness
 How easily a mineral scratches
materials
 Mohs Hardness Scale
Scale from 1 (softest) to 10 (hardest)
 Test by seeing if the mineral can scratch
different objects (like human fingernail, copper,
penny, glass, steel file)

Physical Properties of Minerals
(can be used to identify the mineral)
Cleavage & Fracture



The way the mineral breaks
Cleavage—minerals break
along smooth, flat surfaces
and every fragment has the
same general shape
Fracture—minerals that break
at random with rough or
jagged edges
Cleavage or Fracture?
1.
4.
2.
3.
Physical Properties of Minerals
(can be used to identify the mineral)
Other Properties





Specific gravity (*excellent clue to
mineral’s identity) http://www.childrensmuseum.org/geomysteries/cube/b4.html
Attraction to magnets
Bending of light
Reaction with hydrochloric acid
Smell & taste
!!!!!Minerals!!!!!