Chapter 3
Minerals
Mineral
Naturally occurring
Inorganic
Solid
Definite structure –
crystalline – solid in
which the atoms are
arranged in a repeating
pattern.
Definite composition
Ex; Quartz - SiO2
Coal
Naturally occurring
Made of organic material
plants
Solid – non crystalline
Definite composition
Cubic zirconium
Man made
Inorganic material
Solid
Crystalline structure
Definite composition
ice
quartz
Hexagonal Crystal
( 6 sides)
Had plenty of time and
space to allow the
crystal to grow
Same crystal shape
Formed in a tight
space so you cannot
see the outward
appearance of a crystal
Fluorite
Pyrite
Galena
Aggregate –
clumps of
minerals
joined
together
Pyrite
Galena
Halite
Calcite- double refraction
Formation of minerals
1. Cooling magma – cooling slows particles which
cause them to move closer together and form
compounds.
- molecules arrange themselves into
repeating patterns
- type and amt of minerals depend on
the composition of the magma
- many different minerals form
- quicker magma cools, faster crystals
form, smaller crystal size/or no apparent crystal
2. Crystal from solution – minerals
dissolved in liquids
- when liquid evaporates the
mineral is left behind
3. Crystals from supersaturated solution –
molecules of the mineral fall out of the
solution.
98% of the earth’s crust is made of only 8
elements
Silicates – most common rock forming
elements
- minerals that contain O and Si
Mineral Identification
Physical properties – observable properties
Hardness – how easily mineral can be
scratched
Talc – soft mineral
-scratch with fingernail
- talcum powder
Diamond – hardest of all minerals
- only another diamond can scratch it
- used in special cutting tools
Moh’s Scale of Hardness
The Girls Can Flirt And Other Queer Things Can
Do
1.
talc
2. gypsum
3. calcite
4. fluorite
5. apatite
6. feldspar (orthoclase)
7. quartz
8. topaz
9. corundum
10. diamond
Luster
How light is reflected
from a mineral’s
surface
Metallic – shines like
metal
Nonmetallic luster
Nonmetallicglassy,
dull,
pearly,
Silky
Earthy
Greasy
Color
Can’t be depended
upon because some
minerals have a
variety of colors
Some minerals have
the same color
Chalcopyrite – left
Gold nugget - below
Streak
Powdered form of a
mineral
Rub the mineral across
a piece of unglazed
porcelain
Left – hematite
Right - pyrite
Graphite
Streak – black to gray
Hardness – 1
Feels – greasy
Luster – metallic
Opal
No streak
Hardness 5-6
Luster – waxy
Fracture and Cleavage
Cleavage – when a
mineral breaks along
smooth flat surfaces
Fracture – minerals
that break with rough
or jagged edges
Conchoidal – circular
pattern in break
irregular
Other Properties
Magnetic
Double images
Taste – halite/salty
Smell – sulfur – smells
like rotten eggs
Reaction to HCl –
bubbles.
Fluoresence'