Transcript Rocks and Minerals

 What are minerals?
 What are the processes by which minerals
form?
 A huge portion of Earth is made of minerals
(most rocks are a combination of minerals)
 Minerals provide nutrients to living things
(like us)
 Minerals are used in business/technology,
construction, and electronics (like computer
parts)
 Minerals are a type of matter and we know that
all matter is made of?
atoms.
 But more specifically, a minerals must meet five
criteria to be called a mineral…
 All Minerals are…
SOLID
Which of the following could be a mineral?
 All minerals are
Inorganic= were never
alive
Which of the following could be a mineral?
Inorganic- was never alive
Organic- is currently alive
 All minerals occur naturally.
•If that is true, which of the following is
not made of minerals?
 All minerals have a definite chemical composition.
 This means that in each individual mineral, certain
types of atoms will come together (bond) in certain
ways
 Ex. this is similar to how 2 hydrogen's and one oxygen
come together to form the most important molecule
on Earth!
O
H
H
 The atoms in minerals are arranged into orderly
-
-
structures (specific shapes).
Cubic
Tetragonal
Orthorhombic
Hexagonal
Minerals and Rocks
Minerals are
individual crystals
of all the same stuff
Coal
Gneiss
Scoria
Rocks are
combinations
of minerals
***You should see lots of different
minerals in every single rock
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!)
***Notice how each is one single type of crystal!
 Amethyst

Galena
Calcite
Gold
Garnet
Pyrite
 Mineral crystals can form in two ways:
From stuff
dissolved in liquids
(Evaporation & Hot Water)
From Cooling
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)
When the hot material cools fast, it has
smaller crystal size. When it cools slowly, it
has large crystals.
Granite
You can see
individual crystals
in Granite
=cooled slowly
Rhyolite
You can’t see many
individual crystals in Rhyolite
=cooled very fast
 Some minerals form when solutions/mixtures
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.
**All the white stuff = salt mineral crystals that formed
when the water of this lake evaporated.
The mineral material was left behind
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.
 Some minerals display strange properties.
 These can include: Magnetism, fluorescence, and reactivity.
Fizzing!
The particles of minerals
of this rock act like magnets
These minerals glow
in the dark.
A black light really brings it out!
The minerals in
this rock react
with acid
 Rocks are nothing more than a mixture of different
mineral crystals.
***All three minerals are
combined in a Granite rock
Granite
Quartz
(mineral)
+
Biotite
(mineral)
+
Feldspar
(mineral)
=
This is Continental
Crust
(Rock)
 Rocks are nothing more than a mixture of different
mineral crystals.
***Both minerals combined
make Basalt
Pyroxene
(mineral)
+
Olivine
=
(mineral)
This is Oceanic Crust
Basalt
(rock)
Geologists classify rocks into three major groups
depending on how they are formed:
Igneous rock, Sedimentary rock, and Metamorphic rock.
 Formed from cooled Lava and Magma
As an Example:
Liquid hot lava
can become
***When the lava cools and turns into a solid, it can turn into quartz!
- Igneous Rocks
1. Take some Minerals &
Gasses – Mix well
2. Add Heat Energy & Melt
(cook for +/-10 thousand years)
3. Turn to Magma
(Liquid Molten Rock)
4. Cool & Crystallize
(Intrusive/Extrusive)
5. Igneous Rock
Serve and Enjoy
Minerals + Heat
under the
ground
 Formed inside the crust/mantle.
 These types always have large visible crystals.
(cooled slowly)
 Ex: Granite and Gabbro
This is a special kind of Granite
called: “Pink Granite”
***Notice that both rocks have
easy to see crystals
 When magma from below rises up, but does not make
it to the surface, the minerals start to crystallize slowly
and form large crystals.
Notice the bulge that forms!
= there might be an eruption soon!
Magma
Or not…
This became Granite
because it never made
it to the surface!
 Formed on top of the crust.
 Small, hard to see crystals (cooled quickly)
 Ex: Pumice, Obsidian
***No visible crystals in either rock
 When magma from below rises and punches through,
the minerals don’t have time to crystallize – therefore,
Blam
they produce rocks with small crystals.
!
ash, gasses,
volcanic glass, etc.
Other types of
rock can be
blasted out
Lava Flow
(Outside)
Magma
(inside)
The lava will quickly
cool into solid rock!
 Granite and Rhyolite
Rhyolite: can you see crystals?
form from the same type
of cooled magma.
 If the magma cools
rapidly, smaller crystals
form and Rhyolite rock
is produced.
There are no visible crystals!
 If the magma cools slowly,
larger mineral crystals
form and the type of rock
known as granite forms.
Granite: can you see crystals?
There are lots of visible crystals!
 Formed by sediments (pieces of rock, shells, and
dead organisms) becoming “cemented” (stuck)
together.
Sandstone
Coal
Limestone
***You can see lots of different stuff
stuck together in these rocks!
Conglomerate
1. Rocks exposed at
the surface
2. Weather (Break Up)
Rise to the
Surface
Weathering
& Erosion
Sedimentation
& Deposition
3. Erode (Carry Away)
Compaction
4. Sedimentation &
Deposition
5. Compaction &
Cementation
Cementation (stuck
together)
***Notice that different
layers of “sediments” are forming
1. Start at the
Surface
2. Weather (Break Up)
3. Erode (Carry Away)
4. Sedimentation &
Deposition
Layers of sand and sediments
Rain moves sand, dirt, and
rocks down to the ocean
5. Compaction &
Cementation
Igneous rock
© Beadle, 2009
Sediments worn away
gather here!
 Made from other rocks
Take notice of small
pieces of rock stuck
together
 Made from parts of living things.
Notice all the shells
stuck together
 Formed through evaporation.
 (ex: limestone)
All this Limestone used to be
on the bottom of an ocean!
(ocean floor)
In fact, we call Limestone:
Calcium Carbonate!
***Limestone is made up of the
Calcium (shells) and Carbon (bodies) from
once living things (dead)
in the water (oceans).
 Particles of shells/rocks stuck together
 Dull (not shiny)
 Straight layers
 Fossils (often)
Sandstone: pieces of sand stuck together
The layers are going in this direction
can you see them?
 To “Morph” means to change it!
“…more than meets the eye!”
• Rocks that have changed.
• They were once Igneous or
Sedimentary rocks that got buried
DEEP under ground.
• The heat and pressure from being
deep underground changed the
rocks.
• Has large, inter-grown crystals in
thin “bands” (Foliated) or clusters
(Non-Foliated).
1. Get some pre-formed rock –
Igneous or Sedimentary will do.
2a. Add Heat
“cook it”
2b. Squeeze
(pressure) to
“Foliate”
3. Cool & (Re)-Crystallize
Heat and pressure
4. Metamorphic
Rock!!!
Note: If it melts
completely and cools; It
will turn back into an
Igneous Rock
Rocks are
“Morphed”
 Mineral crystals aligned in parallel layers.
Notice that the crystals
have been squished into
mostly straight lines.
The shoes represent the pressure
caused by all the rock above
the crystals
The “playing cards” represent
mineral crystals in a rock!
Crystals are large
Crystals have become “squished”
Crystals are
Random in
their locations
Granite=large, randomly
Gneiss=smaller, lined
located crystals becomes
up crystals
Crystals
line up in
mostly
straight lines
 Gneiss:
 Schist:
 Slate:
Can you see all the
Straight layers of crystals?
Cooling
Solidifying
Cooling
Solidifying
Heat and
Pressure
Any type of rock can be
changed into any of
the other types of rock
by natural forces.
Review Questions
1. What are three major types of
rock found in nature?
2. All new rock starts out as what
type of rock?
3. What is the difference between
intrusive and extrusive
igneous rock?
Review Questions
4. How are sedimentary rocks formed?
5. Describe the three types of
sedimentary rock.
6. What three types of forces are
present when metamorphic rock
forms?
Review Questions
7. Describe the two major types of
metamorphic rock.