Chapter 5
Minerals of Earth's Crust
Section 1 What is a Mineral?
Minerals:
___________________________________________________
_________________________________________________________
Characteristics of Minerals
There are 4 characteristics that the object must fit into
1. _________________________________________________?
2. _________________________________________________?
3. _________________________________________________?
4. _________________________________________________?
Kinds of Minerals
There are approximately __________________ known minerals
Approximately 20 of the minerals are called rock forming and approximately _____%
makes up the earth's crust. ______% of the minerals are a combination of the common
elements. The rest of the minerals are rare or in rare quantities.
Silicate Minerals
Silicate
A___________________________________________________.
Most common minerals that make up _______% of the earth's crust
Common ones include: quartz and the feldspars
Non Silicate Minerals
Carbonates
________________________________________
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Halides
___________________________________________________________
Native Elements
Composed of ___________________________________________
Gold Au
Silver Ag
Sulfur S
Diamond - C
Oxides
Contain _____________________________________________________
Sulfates
Contain ______________________________________________________
Sulfides
Contain _____________________________________________________
Crystalline Structure
Crystal:
______________________________________________________
Can be seen with your eye, microscope or x-ray
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Crystalline Structure of Silicate Minerals
Silicon-Oxygen Tetrahedron
Basic building block of rocks in the earth's crust
4 Oxygen
1 Silicon
Hint - know this name and this shape it may come up again!!!!
Hornblende -
Mica -
Silicon Tetrahedrons form the shape of a chain.
Oxygen will bond with Si to form a bumpy thing
Si tetrahedrons form a flat sheet
Pyroxene- Si tetrahedrons form a chain
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Section 2 Identifying Minerals
Mineralogy
____________________________________________________
Mineralogist
____________________________________________________
Physical properties of Minerals:
1. _________________Easy to determine but not too good because many minerals have the
same color
Also many minerals may have more than one color.
Reasons: 1.
impurities may change color
2.
Air may change color
3.
Many different minerals may have the same color
2. . ______________________ - using an unglazed white tile,
rubbing the mineral over the tile will produces a powder. Each
mineral's streak is always the same color no matter what the color of
the mineral is.
3. __________________________
Metallic - looks and shines like a metal
Non metallic - can be shiny but does not look like a metal
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4. ___________________________________
Cleavage
The tendency of a mineral to split easily or separate along flat surfaces.
Ex. Mica - one directional perfect cleavage
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Fracture - when minerals break along a surface that is not a
cleavage surface.
1c. Conchoidal - shell like fracture
Ex. Obsidian
2c. Fibrous -
splintery - produces jagged, sharp edges
Ex. copper
3c. Uneven or irregular - generally rough surfaces
5.
________________ - resistance to being scratched. If a
mineral scratches
another mineral it is harder than the other
mineral.
Moh's Hardness Scale
Uses objects easily found with earlier geologists
1.
Finger Nails
2.
Copper penny (prior to ~1975)
3.
Steel (knife)
4.
Glass (watch or glasses)
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Mineral
Hardness
Mineral Name
Hardness Test
*1
Talc
easily scratched by a finger nail
Softest Mineral
2
Gypsum
scratched by a finger nail
3
Calcite
Barely can be scratched by a copper penny
4
Fluorite
easily scratched by a steel knife or glass
5
Apatite
scratched by a glass
*6
Feldspar
Can be scratched by glass but not steel
*7
Quartz
able to scratch steel and glass
Hardest Common Mineral
8
Topaz
it scratches Quartz
9
Corundum
it scratches Topaz
*10
Diamond
Hardest mineral - scratches all minerals
* Know these - become familiar with the rest
6. __________- a shape only easily observed with large crystals.
7.
____________________
Ratio of mass of a substance to the volume of the substance
Density = Mass
Volume
Specific Gravity:
Simple definition:
The objects weight in air verses its weight in water (compares densities)
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Special Properties
Fluorescence - ___________________________________________
Phosphorescence - _________________________________________
Double Refraction - _______________________________________
Ex. Calcite
____________ - minerals can be picked up or is attracted to a magnet.
Ex. Magnetite
____________ - the ability to release energy and activate a Geiger counter
Ex. Uranium
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Another way to determine a mineral
Acid Test:
Weak acids can cause calcite to fizz (bubble) like putting water on an
"Alka Seltzer" tablet.
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