1. Mineral Formation

2. The Earth’s crust is made up of two things:
Minerals and Rocks
Coal
Gneiss
Scoria
Rocks are
combinations
of minerals
Minerals are
individual crystals
of all the same stuff
***You should see lots of different
minerals in every single rock

3. Main Concept: Minerals are the building blocks of rocks!
There are four main properties of a mineral:
a) It must occur naturally (not fake)
b) It is made of non-living material (never alive)
c) It has a definite chemical formula (NaCl=salt)
d) It has a crystal structure (OOoo! Precious!)
What is a mineral?

4. Examples: Amethyst Calcite Garnet Galena Gold Pyrite
***Notice how each is one single type of crystal!
Amethyst Calcite Garnet
Galena Gold Pyrite

5. Where do minerals come from?
Mineral crystals can form in two main ways:
From stuff
dissolved in liquids
(Evaporation & Hot Water)
From Cooling
molten material

6. 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 cools on the surface.
When these liquids cool to a solid, they form crystals (minerals).
Size of the crystal depends on time it takes to freeze into a solid.
“Intrusive” Cooling:
Magma cools slowly
(Long Time = Large Crystals)

7. individual crystals in Rhyolite
Minerals Crystal Size
When the hot material cools fast, it has smaller crystal size. When it cools slowly, it has large crystals.
Granite
Rhyolite
You can see
individual crystals
in Granite
= cooled slowly
You can’t see many
individual crystals in Rhyolite
= cooled very fast

8. Minerals formed by Evaporation
Some minerals form when solutions/mixtures evaporate:
When water evaporates, it leaves behind the stuff that’s dissolved in it.
The longer it takes to evaporate, the larger the crystal.
i.e. salt & water – ocean,
Halite, Gypsum, Calcite.
***All the white stuff = salt mineral crystals that formed
when the water of this lake evaporated.
The mineral material was left behind

9. These salt crystals formed from salt water because as the water evaporated, the salt wasn’t dissolved anymore. So the chemical energy in salt takes over and crystals form.

10. How do we identify Minerals?
We use the different physical and chemical properties
of the mineral to identify it from other different minerals
Luster: Describes how light is reflected from a minerals surface.
Streak: Is the color of the minerals powder when dragged across a surface.
Crystal shape: Different minerals make different crystal shapes
Hardness: Hardness is determined by a “scratch test”.
Color: Every mineral has some natural color…ex: Gold, Blue, Clear…
Etc: There are many other types of properties we use but these are the big ones

11. Special Properties Some minerals display strange properties.
These can include: Magnetism, fluorescence, and reactivity.
Fizzing!
These minerals glow
in the dark.
A black light really brings it out!
The minerals in
this rock react
with acid
The particles of minerals
of this rock act like magnets