Download Minerals - Miss Rudisill`s Webpage

Ms. Rudisill
1. Made up of elements in the earth’s crust!
2. Minerals must have the following 5
characteristics:
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Occurs naturally
Solid
Definite chemical composition
Atoms are arranged in an orderly pattern –
crystal
Inorganic
3) 8 elements make up 98.5 % of the earth’s
crust
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Oxygen and Silicon are the most abundant
90% of ALL minerals are made with Oxygen and
Silicon
4) Most Minerals are compounds

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Halite – NaCl
Quartz – SiO2
5) A few minerals are single elements, native
elements
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Silver – Ag
Diamond - C
1. Magma – molten rock
a) Atoms in magma solidify
b) Magma starts to cool
c) Atoms move close together and form
compounds
d)Types of minerals that form depend on the type
and amount of elements in the magma
e) Cooling time determines size of minerals
Long cooling time = large minerals
Short cooling time = small minerals
3) Pressure
a)
b)
c)
d)
e)
A rock is put under great temperature and
pressure
Minerals begin to break down chemically
Pressure becomes great enough to change the
minerals without melting them.
Atoms recombine forming new minerals
Minerals grow in opposite direction from the
pressure.
4)Water
a) Evaporating saltwater
-bodies of saltwater evaporate
-As saltwater evaporates the minerals
crystallize
-Ex: Gypsum and Halite
b) Surface and groundwater
-Surface and groundwater carry
dissolved materials into lakes or seas
-Dissolved minerals settle on the bottom
of the lake or sea
-Ex: Mica
c) Hot-water Solutions
-Groundwater makes its way through the
ground in Earth’s surface
-Magma inside Earth mixes with the
water
-Water evaporates and causes the
dissolved metals and other elements to
precipitate out of the water
-ex: gold, copper, sulfur, pyrite, and
galena
 Source
of metals - Ores
 Gemstones/Jewelry
 Abrasives
 Fertilizer
 Glass
 Color
 Luster
– the way a mineral shines in light
 Crystal

Structure
Crystal size is determined by the amount of time
it has had to cool.
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Long cooling time creates large mineral crystals
Short cooling time creates small mineral crystals
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Some minerals have distinct colors
Many minerals have similar colors
Some minerals have many colors
Some minerals change colors
 Streak
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Color of a minerals powder
Obtain streak by rubbing the mineral on an
unglazed white tile (streak plate).
Color of the mineral may vary, but the streak is
always the same
Streak Rules
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Streak of a metallic mineral is at least as dark as the
mineral
Streak of a nonmetallic mineral is usually colorless or
white
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Metallic – shines like polished metal
Nonmetallic – may be shiny but not like a metal
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Vitreous – like glass; Quartz
Pearly - Mica
Adamantine- hard brilliant luster; Diamond
Greasy
Oily
Dull
Earthy
 Crystal
is an orderly arrangement of atoms in
a mineral
 All minerals have a crystal structure, but you
cannot always see the structure.
 Six Crystal Systems
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Cubic
Orthorhombic
Tetragonal
Hexagonal
Monoclinic
Triclinic

Cleavage
Tendency of a mineral to split easily along flat
surfaces.
 Useful because cleavage surfaces can be observed
even on tiny mineral grains.


Fracture
When minerals break in directions other than along
cleavage surfaces.
 Conchoidal Fracture – surface is smooth and curved
like the inside of a clam shell
 Splintery Fracture – Jagged surface with sharp edges
 Irregular Fracture – leaves generally rough surfaces
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 Hardness
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Resistance to being scratched
Use the Mohs Scale of Hardness
Scale was created by Friedrich Moh
Scale goes from 1 (softest mineral) to 10 (hardest
mineral)
Determining Hardness
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If a mineral can be scratched by an object than it is
softer than that object.
If a mineral is not scratched by an object than it is
harder than that object
Mohs’ Scale of Hardness
Mineral
Simple Test
Talc
Fingernail scratches it easily
Gypsum
Fingernail scratches it
Calcite
Copper Penny scratches it
Fluorite
Steel knife scratches it easily
Apatite
Steel knife scratches it
Feldspar
Steel knife does not scratch it, it
scratches window glass easily
Quartz
Hardest common mineral; it scratches
steel and hard glass easily
Topaz
Harder than any common mineral
Corundum
It scratches Topaz
Diamond
Hardest of all minerals
 Fluorescence
– minerals that glow under
ultraviolet light.
 Magnetism – magnetic
 Acid Test – mineral reacts when in contact
with Hydrochloric (HCl) acid.
 Specific Gravity
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Ratio of its mass to the mass of an equal volume
of water.
Tells you how many times denser the mineral is
than water.
 Double
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Refraction
Iceland Spar Calcite
Causes single object to appear as two objects
when viewed through the calcite
 Taste
– Example Halite has a salty taste
 Salty
Taste
 Double Refraction
 Magnetic
 Heavy
 Greasy (smudges on fingers and paper)
 Flakes apart
 6-sided crystal (you might have two of
these!)
 Almost perfect square/rectangle pieces
 Feels soft like powder!
 Minerals
are divided into two groups based
on the elements they are composed of.
 Silicate Minerals
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Minerals that contain a combination of silicon
and oxygen
Silicate minerals can still contain other minerals,
but are made up mostly of Silicon and Oxygen.
 Nonsilicate
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Minerals
Minerals that do not contain a combination of the
elements Silicon and Oxygen
These minerals may have one of these minerals