This document discusses how minerals are identified. It begins by defining minerals as naturally occurring inorganic solids with a crystal structure and specific chemical composition. It then explains that minerals are identified based on their physical properties, including hardness, luster, streak, color, cleavage, and fracture. The document focuses on Mohs hardness scale as an important identification tool and provides examples of different luster, streak, color, cleavage and fracture properties.

1. What are they?
Why are they important?
How are they identified?

2. What are minerals?
A naturally forming inorganic
(non-living) solid
Crystal structure due to internal
arrangement of atoms.
Specific chemical composition

3. Minerals are inorganic
Never been alive
Example: copper, quartz, calcite.
Fossils are NOT minerals- they
were once living
Natural gas and oil are NOT
minerals- they came from once-
living organisms

4. Why are minerals important?
Essential natural resources
“If it can’t be grown it must be mined”
 Mining –is taking valuable minerals out of the
Earth.

5. What do we mine for?
Metals- buildings, homes, plumbing,
electrical, manufacturing, transportation
Rocks- buildings, roads, manufacturing
Jewelry, currency, art
Health, medicine

7. Mineral Identification
Properties
1. Hardness
2. Luster
3. Streak
4. Color
5. Cleavage
6. Fracture

8. Moh’s Hardness Scale
Hardness is the ability to scratch another
mineral
Moh’s uses 10 relatively common
minerals to compare their relative
hardness
Uses common items of known hardness
to compare with ten minerals (fingernail,
steel nail, glass plate, copper penny)
Very important in mineral identification

9. Moh’s Hardness Scale
1. Talc
Softest mineral
2. Gypsum
Gypsum can
scratch talc.

10. Moh’s Hardness test
A fingernail can scratch
both talc(1) and
gypsum(2)
A fingernail is assigned
the hardness number of
2.5

11. 3. Calcite
Calcite can
scratch
gypsum
4. Fluorite
fluorite can
scratch calcite
and softer
minerals

12. Moh’s Hardness Test
A copper penny has
a hardness of “3”
A copper penny can
scratch minerals
softer than a 3

13. 5. Apatite
 Can scratch Fluorite
6. Potassium
Feldspar
 “K-spar”
 K spar can scratch all
softer minerals. None
of the softer minerals
can scratch it.

14. 7. Quartz
so hard it can
scratch glass
8. Topaz
Topaz is
harder than
quartz

15. 9. Corundum
Can scratch Topaz
10. Diamond
is the hardest
natural substance
known
It is harder than
all other minerals

16. Luster
Quality and intensity of
light reflecting off the
faces of the crystal
Non-metallic
Metallic

17. Non-metallic luster
 Shiny like a metal
Metallic luster
• Dull/ Earthy
• Waxy, greasy or soapy
• Glassy
• Pearly
• Silky

18. Vitreous luster
Glasslike
Most
common
Ex. Quartz

19. Waxy Luster
Has the look
of wax
Examples:
chert,
smithsonite

20. Earthy/Dull Luster
Non-reflective
surface
Dirt-like
appearance
Examples: barite
“roses”; bauxite,
limonite

21. Pearly Luster
Has the
shine of
a pearl
Ex. Mica

22. Silky Luster
Looks like silk
Used to
describe
fibrous
minerals, such
as asbestos

23. Metallic Luster
Looks like
shiny metal
Copper,
silver, gold,
platinum,

24. Mineral Streak
The color of the powder left when
a mineral is rubbed on a streak
plate
The ability/inability of a mineral
to create a streak helps ID it

25. Mineral Streak
When rubbed on a
ceramic tile, some
minerals leave
certain color
streaks.
(EX) Grey
hematite leaves a
red streak

26. Color
Color is based on what wavelength of
light is absorbed and reflected.
Color is the LEAST reliable mineral
ID test
 Many different minerals have the same
color.
 The same mineral can often have different
colors

27. ID by color
Sulfur
copper

28. Same mineral-
Different colors
quartz

29. Same Color- Different
Minerals
Gypsum
Calcite
Albite
Halite

30. Cleavage
How a mineral breaks or splits along
planes of their crystal structure
Cleaves along the same parallel plane
over and over again
Occurs in minerals with specific planes
of weakness
Several different types of cleaving

31. Octahedral cleavage
Multiple
cleavage
planes-
Fluorite

32. Cubic Cleavage
90 degree
angles
Six-sided cube
Galena
Halite

33. Rhombohedra Cleavage
Calcite

34. Fracture
Mineral breaks along
uneven lines and
results in rough and
curved surfaces.
Conchoidal Fracture-
looks like a clam
shell.
Due to atomic
configuration.

35. Other Properties
used to ID minerals
Magnetism
Acid test – calcium bubbles
when touched with an acid:
calcite
Fluorescence – glow under UV
light
Salty- contain naturally occurring
salt: (halite)