Minerals are naturally occurring inorganic solids with definite chemical compositions and crystalline structures. The internal arrangement of atoms in minerals largely determines their physical and chemical properties, which can be used to identify them. Some key properties used to identify minerals include color, streak, luster, hardness, density, cleavage, fracture, and crystal structure. Hardness refers to a mineral's resistance to scratching, not its brittleness, and is measured using Mohs scale.

1. Rocks &
MineralsNOTES

2. Mineral
A Naturally OccurringNaturally Occurring
Inorganic SolidInorganic Solid with a
definite chemicalchemical
compositioncomposition and
crystaline structurecrystaline structure.

3. Mineral Properties &
Identification

4. Crystal structure & chemical
composition of minerals largely
determine physical & chemical
properties used to identify

5. What causes minerals to have
different physical properties?
their internal arrangement of atoms

6. The Main Physical Properties
Used to Identify Minerals
Color
A poor indicator!
Minerals can be multiple colors
Many minerals are the same color

7. The Main Physical Properties
Used to Identify Minerals
Streak
the powder form of a mineralmore reliable than color

8. Streak
-Color of finely crushed residue or
powder of a mineral
-When you write on chalkboard,
you observe streak of chalk
-Streak of mineral usually
consistent, making streak color
more useful in identifying than
mineral color

9. The Main Physical Properties
Used to Identify Minerals
Luster
how light reflects off a mineral
metallic non-metallic
looks like a
metal
looks earthy, waxy,
greasy or brilliant

10. Luster
- Shine from an unweathered
mineral’s surface
- Way a mineral looks in reflected
light
- 2 groups of luster
Metallic
shine like surface of clean stainless steel pot
Example: Pyrite & galena
Non-Metallic
can be glassy like black hornblende & quartz
can be pearly like muscovite mica

11. Hardness
The Main Physical Properties
Used to Identify Minerals
resistance to being scratched
It is NOT the same as breaking!
For example:
You can break glass easily with steel.
However, steel will not scratch glass.

12. Hardness
The Main Physical Properties
Used to Identify Minerals
Scratchability of minerals, not how
easily it breaks
For example:
Diamonds are hardest mineral, but if you
drop an unmounted diamond on a tile floor
it will break

13. MOH’S SCALE OF
HARDNESS
Hardne
ss
Mineral Hardnes
s
Mineral
1
(softest)
Talc 6 Orthoclase
2 Gypsum 7 Quartz
3 Calcite 8 Topaz
4 Florite 9 Corundum
5 Apatite 10
(hardest)
Diamond

14. - Quick way to determine relative
hardness is to use piece of
window glass
1. If mineral scratches glass it is
hard
2. If mineral doesn’t scratch
glass it is soft

15. Density
-Each mineral has specific density or
narrow range of densities
-Often stated as specific gravity, which
has no units
-Specific gravity is density of mineral
compared to density of water
-density is a good test to distinguish
gemstones, because it doesn’t harm
samples

16. Cleavage
- Tendency of mineral to break along zones
of weakness & form smooth to semi-
smooth parallel sides or surfaces
- Cleavage surfaces can often be
distinguished from sides without by having
a shiner or more brilliant luster
- If minerals lack preferred zones of
weakness, then it will demonstrate uneven
breaking surface (fracture)

18. Fracture
The Main Physical Properties
Used to Identify Minerals
the mineral breaks randomly

19. Crystal Structure
-Outward geometric shape of
mineral, crystal form, reflect
structure
-Orderly arrangement of atoms in
mineral
-Any mineral can have many
different crystal shapes

20. Other Mineral Properties
- Some chemical properties of minerals
are used for identification
- Reaction of a mineral with acid