Mineral Properties
& Identification
The story of minerals so far….
• Minerals formed from elements that originated in exploding
stars, made a nebula and then formed our solar system
• Minerals are solid, naturally occurring, inorganic, made of
chemical elements and have an internal arrangement of atoms
(crystal structure)
• Native minerals are made of 1 element: gold, sulfur, iron
• Top elements that make up the Earth’s crust are: oxygen, silicon,
aluminum, iron, calcium, sodium, potassium, magnesium
• Most minerals are compounds: NaCl, CaCO3 SiO2
• A rock is a mixture of 1 or more minerals: granite
• Limestone is made of only one mineral – calcite.
Observe
• Minerals #1 - #39
• Separate/Group the minerals by properties:
– How are they alike?
– How are they different?
– Regroup them again using another similar property.
Properties used to Identify Minerals
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Color
Odor
Shiny or dull (Luster)
Hardness (scratches)
Streak color (on streak plate)
Solubility in water
Dissolve in water or react in acid
Cleavage (split or shatter when hammered)
More properties to I.D. minerals
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Optical properties: double refraction
Magnetic
Heavy (specific gravity)
Crystal shape
Fluorescent
Taste?
Radioactive
In each
I.D. Lab bag:
8 minerals
1 Hand lens
1 Penny
1 Glass plate
2 Streak plates
1 magnet
1 Nail
1 yellow
2 clear
2 pink
1 dark red
1 flat
1 gold
Physical Properties of Minerals
• Color: light or dark, yellow, gold, pink….
• Luster:
– metallic,
– Non-metallic: dull, glassy,
vitreous, pearly, adamantine
Light: transparent, opaque, double refraction,
Streak
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The color of the mineral in its powdered form.
Rubbing the mineral on a streak plate.
Streak is more reliable than color:
Streak is a consistent property of a mineral.
Metallic minerals generally have a dark streak,
– Non-metallic mineral do not
Two different colored forms of the SAME mineral:
SAME colored streak
Hardness
Mohs scale
of hardness
• Relative scale:
comparing the
hardness of a mineral
to a known object.
• 1-10
• Diamond being the
hardest 10
• Talc is the softest 1
• Fracture
Quartz (glass) fractures and shatters
into irregular-shaped pieces with
no flat planes
• Cleavage: the tendency of a mineral to break along
flat planes of weak bonding
Halite will cleave into many smaller
pieces each with 3 planes at 90°
Three examples of perfect cleavage –
3 flat planes (sides)
fluorite, halite, and calcite
Mineral
Specimen
Number
Color
Luster
1
yellow
dull
2
3
4
5
6
7
8
Light
interaction
Streak
color
opaque yellow
Hardness
number
1-2
Cleavage
Or Fracture
Soluble
in water
fracture insoluble
Solubility
in acid
Other
Properties:
Magnetism,
Fluorescence
insoluble Smells like
rotten eggs
Mineral name
page 700- 701
sulfur
Name
1
sulfur
2
Pyrite
3
Mica
Color
Luster
Light
Interaction
Streak
Hardness
Cleavage
Smell
Sol.
water
Sol.
acid
Yellow
Dull
Opaque
Yellow
1-2
none
Rotten
Egg!
IS
IS
Gold, metallic,
shiny
opaque
black
6
none
none
IS
SS?
white
Pearly,
flat
Transparent
translucent
none
2-3
Perfect!
1
direction
peels
none
IS
IS
Clear
shiny
Transparent
Double
refraction
None
white
3
perfect
none
IS
YES!
FIZZ
Clear, white
Shiny,
Tastes salty
translucent
none
2-2.5
Perfect!
3
direction
90° angle
none
Yes!
dissolve
s
IS
Dark redbrown
dull
opaque
Redbrown
3-4
none
None or
earthy
IS
SS
Salmon pink
opaque
none
6
Good
2
direction
none
IS
IS
Pink, clear
glassy
translucent
none
7
None
fractures
concoidal
none
IS
IS
(Muscovite)
4
5
calcite
Halite
(Salt)
6
7
8
hematite
feldspar
Quartz
Determining the Specific Gravity of
a Mineral
1.
2.
3.
5.
6.
Get out a piece of notebook paper.
Title: SpG & Mineral I.D. (pg. 112-113)
Copy Data Table 1 on page 112.
Copy the formula on pg. 113
Collect the data using a balance
7. Use the table on pg. 113 to Identify the mineral
8. Answer questions #3-8 on page 113
Mineral Data Gravity
etermining Specific
Mass in air
Mass suspended in water
Change in mass from air to water
Specific Gravity (calculated)
Specific Gravity (accepted value)
Name of mineral
SpG = Mass of mineral in air
change in mass
Mass (g)
Suspend the mineral from a piece of string in a
beaker of water. Find its mass.
So, according to your data, which has a higher
specific gravity? Metals or non-metals?
Specific Gravity of Some
Common Minerals
SpG
Sulfur
2.1
Gypsum
2.3
Calcite
2.7
Chalcopyrite
4.2
Pyrite
5.0
Magnetite
5.2
Galena
7.2
Practice
Calculate the Specific Gravity of the mineral
using the mass measurements.
Mass in air:
Mass in water
SpG =
Mass in air
Loss of mass
15.0 g
-12.0 g
3g
15.0 g
3.0 g
= 5.0
What mineral is this?
Mineral Flow Chart
in your notebooks copy the chart below
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Color? dark or light
_______________
Luster? Metallic or non-metallic ________
Streak? Black, brown or reddish________
Harder than glass? __________________
Cleavage? Yes, no cleavage, 1,2,3,4 planes
Mineral Name _____________