Download Minerals

Mineral & Crystal
Formation
© Beadle, 2009
Minerals
What is a mineral?
• A Mineral is a substance that is:
–
–
–
–
naturally occurring, (Not man made)
inorganic (Not living)
A solid crystal
definite chemical composition
• Minerals are the stuff (ingredients) that make up rocks.
• There are over 3800 Minerals Identified.
Common Minerals: Olivine
• Rich in Iron
– Mantle is made
mostly of this
mineral.
Common Minerals: Quartz
• Found in Igneous
Rocks
– i.e. Granite
• Used for
Electronics, Glass
& Watches
– SiO4
Common Minerals: Biotite
• Found in Igneous
Rocks.
• Thin Black Sheets
Common Minerals: Muscovite
• Separates in sheets
• Heat Resistor & Insulator
– Used for circuit boards
– Windows for heat furnaces.
– KAl2(Si3Al)O10(OH,F)2
Common Minerals: Hornblend
• Found in Granite
• Used in decorative
dimension stone
Common Minerals:
Plagioclase Feldspar
Formation of Minerals
• Three ways to form mineral crystals:
– Evaporation
– Cooling down a super saturated solution
– Cooling down magma/lava
Crystallization
 Mineral crystals can form in three ways:
From Evaporation
From Cooling
Supersaturated Solutions
From Cooling
Magma & Lava
Size of Crystal
• Size of the crystal depends on the amount
of time it takes to form it.
– Long Time = Large Crystal
– Short Time = Small Crystal
– No Time = No Crystal
Crystallization:
 The process by which the atoms in the mineral
are arranged to form a crystal structure.
– Nucleation
– Crystallization
© Beadle, 2009
Mineral Crystals from a Hot
Water Solution
Minerals formed from Hot water
solutions.
 Deep underground, magma can heat
water to a high temperature. Sometimes,
the elements and compounds that form a
mineral dissolve in this hot water.
 When the water solution begins to cool,
the elements and compounds leave the
solution and crystallize as minerals.
Solution Relationship
• Water = Solvent
• + Sugar = Solute
• Both = Solution
(Stuff that dissolves)
(Stuff that gets dissolved)
• Saturated Solution: When the liquid no longer
can dissolve the other substance.
• Super Saturated Solution: As the saturated
solution cools down, it has more stuff than it can
hold and wants to come out of solution
Minerals from Cooling
Solutions
• As the solution cools, the atoms have less and less room to
move and when the solution has cooled sufficiently, the atoms
link together precipitating the mineral.
Minerals Form from Water Solutions Animations 1, 2
Hot Water Solutions
• Pure metals crystallize from hot water
solutions underground in veins – or cracks
within rocks.
– i.e. silver, gold etc.
Mineral Crystals from
Evaporation
Minerals from Evaporative
Solutions
 Sometimes the elements and compounds that
form minerals can be dissolved in water to form
solutions.
 Solution is a mixture in which one substance is
dissolved in another.
 When elements and compounds that are dissolved in
water leave a solution, crystallization occurs.
Minerals formed by Evaporation
 Some minerals form when solutions
evaporate.
 When water evaporates, it leaves behind the
stuff that’s dissolved in it.
 Longer it takes to evaporate, the larger the crystal.
 i.e. salt & water – ocean,
 Halite, Gypsum, Calcite.
Demo: Salt & Epson Salt via Overhead
Salt crystals formed from
solution because as the water
evaporated, the solution left
behind could not hold the same
amount of salt, so the salt
precipitates out in crystal form.
Mineral Crystals from Cooling
Magma/Lava
Minerals & Crystals from
Magma & Lava
Extrusive Cooling:
Lava cools Fast
(Short Time = Small Crystals)
Minerals form from hot magma as it cools
inside the crust, or as lava hardens on the
surface.
When these liquids cool to a solid state,
they form crystals.
Size of the crystal depends on time it takes
to cool down.
Intrusive Cooling:
Magma cools slowly
(Long Time = Large Crystals)
Minerals from Magma
• If magma cools
Slowly, it produces
Large Crystals
– Long Time = Large
Crystals *(L = L)
Volcanic Neck
Columnar Jointing – Large Crystals
Granite Batholiths
Granite
Granite contains large mineral
crystals from cooling deep below the
surface. Erosion has exposed the
surface of these batholiths many
millions of years later.
Lava: Minerals & Crystal
Size
• When the mineral material cools fast, it has smaller
crystal size.
• When the mineral material cools slow, it has large
crystals.
Rhyolite
You can see
individual crystals
in Granite
=cooled slowly
V.
You can’t see many
individual crystals in Rhyolite
=cooled very fast
Granite
Minerals & Crystals
from Lava
• If magma cools very rapidly, it produces
Glass – NO CRYSTALS!
– No Time = No Crystals *(N = N)
Obsidian
And That’s how we get Mineral
Crystallization
From Evaporation
From Cooling
Supersaturated Solutions
From Cooling
Magma & Lava