minerals. what is a mineral? any substance that: 1)is naturally occuring. 2)is solid 3)is organic...
TRANSCRIPT
Minerals
What is a mineral?
Any substance that:
1) Is naturally occuring.
2) Is solid
3) Is organic
4) Has a definite chemical composition.
5) Has a crystal system
Naturally Occuring
• Anything that is found/created in nature.
• Most minerals are formed:– From cooled water
solutions.– From Cooled magma– From evaporation of
solutions.
Inorganic: Any material that did not form from living material.
- Some rocks are organic (coal, limestone).
Definite Chemical Composition
A mineral will always have certain elements in distinct proportions.
- Some are pure
elements:
EX: Gold = Au
Silver = Ag
- Some are compounds:
EX: Pyrite = FeS2
Quartz = SiO2
Crystal Systems
Crystal Structure: The Repeating Pattern of a mineral’s particles.
- Shape of the crystal depends on its definite chemical composition.
- Size depends on how quickly the mineral cooled.- The faster = smaller- The smaller = larger
Mineral properties
There are 8 characteristics that are unique between different minerals.
– Hardness– Luster– Streak– Breakage– Crystal shape– Color– Special Properties– Density (Specific Gravity)
hardnessThe measure of how
easily a mineral can be scratched.
Moh’s Hardness Scale- Tested by performing
a scratch test.- On a scale 1-10
1 = softest (Talc)
10 = hardest (diamond)
Luster
How a mineral reflects light.
- EX: Metallic
Glassy/Vitreous
Streak
Color left behind by a mineral.
Tested by:
Scraping a mineral against a piece of unglazed tile and observing the color left behind.
breakageHow a mineral
breaks apart.
2 ways a mineral can break:
1) Cleavage: Breaks with clean smooth edges.
2) Fracture: Breaks with rough uneven edges.
Crystal systems
The shape of a mineral’s crystal.
• Determined by the chemical composition.
• Common:– Hexagonal– Cubic– Triclinic– Monoclinic
Color and Density
Color: The color of the mineral itself.
- Cannot be used alone to identify a mineral because many minerals can come in many different colors.
Density (specific gravity): How much a mineral weighs depending on how big it is.
D = m/v (mass/volume)
Special properties
Some minerals exhibit unique characteristics
- Magnetism- Radioactivity- Fluorescence- Etc…
How are these used?
We use these 8 properties to identify an unknown mineral.
- Tests are performed and compared to known minerals and their properties.