1. Minerals

2. What is a mineral? Naturally occurring
inorganic (no living thing or remains)
Solid
Definite shape ( arranged in an orderly pattern)
definite chemical composition

3. Is it inorganic? Coal? No, it is not a mineral- How is it made?
magnetite
Yes, a mineral
pearl
No, not a mineral- How is it made?

4. Does it occur naturally?
Quartz
yes, a mineral- one of the last minerals to form from a magma chamber.
Silver
yes, a mineral
steel
no, not a mineral- How is it made?

5. Solid in crystalline form?
Petroleum
no, not a mineral- What is its natural form?
mercury
glass
not a mineral- What is its form?
amorphous

6. Definite chemical composition?
Calcium
yes, Ca a mineral
Graphite
yes, C
Concrete
no, not a mineral- Why?

7. Rock forming minerals Over 3000 minerals
only 20 are common, these are rock forming minerals
two main groups- silicates and nonsilicates

8. Silicates 96% of the crust contain silicon (Si) and Oxygen (O)
Feldspars are the most common silicate minerals, contain Ca, K, and Na
Examples- Orthoclase and plagioclase
Ferromagnesium- contain Fe and Mg

9. Nonsilicates 4% of the crust No silica Six major groups
carbonates-ex. Calcite
halides- ex halite
native elements- Made of one element ex. copper and silver
oxides- hematite and corundum
sulfates- gypsum
sulfides- galena, pyrite

10. Crystal Structure Specific geometric arrangement of atoms or ions
Crystal = natural solid with a definite shape
Can be seen under microscope or with the aid of x rays

11. Identifying Minerals Characteristics of Minerals
Each mineral has specific properties that provide useful clues for identifying minerals.
Optical properties- properties will be identified by looking at the mineral.
Tests- tools are used to run tests on the mineral.

12. Optical Properties Color
Most easily observed
ex. Sulfur is bright yellow, azurite is deep blue
least reliable characteristic
quartz consists of many colors
weathering may hide true color

13. Luster metallic luster- like polished metal like silver
Light reflected from the surface of a mineral
metallic luster- like polished metal like silver
All others are non metallic
vitreous luster- reflects like glass
pearly luster
adamantine- brilliant luster ex. Diamond or gems
other lusters include: waxy, greasy, dull, earthy

14. Crystal Shape Regularly shaped particles, or pattern.
Most crystal shapes are hard to identify.
six crystal systems
cubic ex. Halite, Pyrite
orthorhombic ex. Sulfur
tetragonal ex. Chalcopyrite
hexagonal ex. Plagioclase, Orthoclase
monoclinic ex. Micas
triclinic ex. Kyanite

15. Cleavage
The tendency to split along certain flat surfaces and is related to types of bonds
ex. Mica (general name) splits easily in one direction, it has one perfect cleavage ( splits in parallel sheets)
Example- biotite and muscovite

16. Fracture Some minerals do not break along cleavage planes
instead they fracture or break unevenly into curved or irregular pieces
splintery or fibrous fracture- looks like pieces of broken wood
conchoidal- curved surfaces like the inside of a shell
Chapter 3 &4 Minerals
What is a mineral?
Naturally occurring
inorganic (no living thing or remains)
solid
definite shape ( arranged in an orderly pattern)
definite chemical composition
Is it organic?
Coal?
Yes, not a mineral
magnetite
no, a mineral
pearl
yes, not a mineral
Does it occur naturally?
Quartz
yes, a mineral
Silver
steel
no, not a mineral
Solid in crystalline form?
Petroleum
natural gas
mercury
glass
not a solid, amorphous
Definite chemical composition?
Calcium
yes, Ca a mineral
Graphite
yes, C
concrete
Rock forming minerals
Over 3000 minerals
only 20 are common, these are rock forming minerals
Quartz, orthoclase,plagioclase, muscovite, biotite, calcite, dolomite, halite, gypsum, olivine, pyroxine, amphibole
two main groups- silicates and nonsilicates
Silicates
96% of the crust
contain silicon (Si) and Oxygen (O)
Feldspars are the most common silicate minerals, contain Ca, K, and Na
Ferromagnetism- contain Fe and Mg
Nonsilicates
4% of the crust
No silica
Six major groups
carbonates-ex. Calcite
halides- ex halite
native elements- copper and silver
oxides- hematite and corundum
sulfates- gypsum
sulfides- galena, pyrite
Crystal structure
Specific geometric arrangement of atoms or ions
crystal= natural solid with a definite shape
can be seen under microscope or with the aid of x rays.
Silicates are tetrahedrons and may be single chain, double chain, or sheets
Identifying Minerals
Characteristics of Minerals
each mineral has specific properties that are the result of its chemical composition and crystal structure.
These properties provide useful clues for identifying minerals.
Some properties will be identified by looking at the mineral
other properties will be determined by simple tests
Color
Most easily observed
ex. Sulfur is bright yellow, azurite is deep blue
least reliable characteristic
quartz consists of many colors
weathering my hide true color
Luster
Light reflected from the surface of a mineral
metallic luster- like polished metal
all others are non metallic
vitreous luster- reflects like glass
pearly luster
adamantine- brilliant luster ex. Diamond
other lusters include: waxy, greasy, dull, earthy
Crystal Shape
Regularly shaped particles, or patterns
most crystal shapes are hard to identify
six crystal systems
cubic ex. Halite, pyrite
orthorhombic ex. Sulfur
tetragonal ex. chalcopyrite
hexagonal ex. Plagioclase, orthoclase
monoclinic ex. micas
Streak
The color of a mineral in powdered form
observed by rubbing the mineral against a piece of unglazed ceramic tile called a streak plate
the streak is not always the same color as the mineral
mineral that have a hardness higher hat the streak plate can not be tested
Cleavage
The tendency to split along certain flat surfaces and is related to types of bonds
ex. Mica splits easily in one direction, it has one perfect cleavage ( splits in parallel sheets)
Fracture
Some minerals do not break along cleavage planes
instead they fracture or break unevenly into curved or irregular pieces
splintery or fibrous fracture- looks like pieces of broken wood
Hardness
The ability to resist scratching
hardness does not mean resistance to cleavage or fracture
the hardness of an unknown mineral may be determined by using Mohs Hardness Scale
this scale lists 10 minerals in order of increasing hardness
the softest is talc with a hardness of 1
the hardest is diamond with a hardness of 10
Mohs Hardness Scale
Mineral hardness common test
talc easily scratched by fingernail
gypsum can be scratched by fingernail
calcite barely can be scratched with a copper penny
fluorite easily scratched with steel file or glass
Apatite can be scratched by steel file or glass
Feldspar scratched glass with difficulty
quartz easily scratches steel and glass
topaz scratches quartz
corundum no simple tests
diamond scratched everything
Testing hardness
Galena scratches gypsum but not calcite, its hardness is around 2
if neither of the two minerals scratches the other, they have the same hardness

17. Simple Tests Streak Test
The color of a mineral in powdered form
observed by rubbing the mineral against a piece of unglazed ceramic tile called a streak plate
the streak is not always the same color as the mineral
mineral that have a hardness higher than the streak plate can not be tested

18. Hardness Test The ability to resist scratching
hardness does not mean resistance to cleavage or fracture
the hardness of an unknown mineral may be determined by using Moh’s Hardness Scale
-this scale lists 10 minerals in order of increasing hardness
-Softest is talc with a hardness of 1
The hardest is diamond with a hardness of 10

19. Moh’s Hardness Scale Mineral hardness common test
talc easily scratched by fingernail
gypsum can be scratched by fingernail
calcite can not scratch a copper penny
fluorite can easily scratch a penny
Apatite can barely scratch glass
Feldspar can scratch glass
quartz very easily/deeply scratches steel and glass
topaz scratches quartz
corundum no simple tests
diamond scratches everything

20. Specific Gravity
The ratio of the weight of the mineral to the weight of an equal volume of water.
Each mineral has its own specific gravity
Can be used to identify a mineral

21. Acid Test Used to easily identify calcite
A drop of HCl dropped onto Calcite will cause it to effervesces. The bubbles are CO2 gas.
Dolomite also responds to the acid test but not as violently and only in powdered form.

22. Special Properties Magnetism- Can attach a magnet
Fluorescence- the ability to glow under UV light ex. Calcite appears red under UV
Phosphorescence- minerals that continue to glow after a UV light is removed.ex sphalerite

23. Special Properties con’t
Double refraction- crystals that bend light in such a way that they produce a double image of any object viewed.
Radioactivity- certain atoms have unstable electron or neutron arrangements. These minerals activate a Geiger counter.

24. End of Minerals