Mineral Properties & Identification. The story of minerals so far…. Minerals formed from elements that originated in exploding stars, made a nebula and.
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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
• 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
• Optical properties: double refraction• Magnetic• Heavy (specific gravity)• Crystal shape• Fluorescent• Taste?• Radioactive
In each Mineral I.D. Lab bag:
1 Hand lens 1 yellow
1 Penny 2 clear
1 Glass plate 2 pink
2 Streak plates 1 dark red
1 magnet 1 flat
1 Nail 1 gold
8 minerals
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• 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
Mohs scale of hardness
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
MineralSpecimen Number
Color
Luster
Light
interaction
Streakcolor
Hardnessnumber
Cleavage
Or Fracture
Soluble in water
Solubility
in acid
Other Properties:Magnetism,
Fluorescence
Mineral namepage 700- 701
1
yellow
dull
opaque
yellow
1-2 fracture
insoluble
insoluble
Smells like rotten eggs
2
3
4
5
6
7
8
sulfur
Name ColorLuster
LightInteraction
Streak Hard-ness
Cleavage Smell Sol.water
Sol.acid
1YellowDull
Opaque Yellow 1-2 none RottenEgg!
IS IS
2 Gold, metallic,shiny
opaque black 6 none none IS SS?
3whitePearly, flat
Transparenttranslucent
none 2-3 Perfect!1 direction peels
none IS IS
4Clearshiny
TransparentDoublerefraction
Nonewhite
3 perfect none IS YES!FIZZ
5Clear, whiteShiny, Tastes salty
translucent none 2-2.5 Perfect!3 direction90° angle
none Yes!dis-solves
IS
6Dark red-browndull
opaque Red-brown
3-4 none None orearthy
IS SS
7Salmon pink opaque none 6 Good
2 direction
none IS IS
8Pink, clearglassy
translucent none 7 Nonefracturesconcoidal
none IS IS
sulfur
Pyrite
Mica(Muscovite)
calcite
Halite(Salt)
hematite
feldspar
Quartz
Determining the Specific Gravity of a Mineral
1. Get out a piece of notebook paper.
2. Title: SpG & Mineral I.D. (pg. 112-113)
3. Copy Data Table 1 on page 112.
5. Copy the formula on pg. 113
6. 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
Determining Specific GravityMineral Data Mass (g)
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
Suspend the mineral from a piece of string in abeaker 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
PracticeCalculate the Specific Gravity of the mineral
using the mass measurements.
Mass in air: 15.0 g
Mass in water -12.0 g
SpG =
What mineral is this?
3 g
Mass in airLoss of mass
15.0 g 3.0 g
= 5.0
Mineral Flow Chartin your notebooks copy the chart below
• 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 _____________
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