Transcript Rocks and Minerals

Rock Formation
Main Concept: Rocks are made
from Minerals
• Rocks are nothing more than a mixture of
***All three minerals are
different mineral crystals.
combined in a Granite rock
Granite
Quartz
(mineral)
+
Biotite
(mineral)
+
Feldspar
(mineral)
=
(Rock)
This is Continental
Crust!!!
Rocks are made from Minerals
• Rocks are nothing more than a mixture of
different mineral crystals.
***Both minerals combined
make Basalt
Pyroxene
(mineral)
+
Olivine
(mineral)
=
Basalt
(rock)
This is Oceanic Crust!!!
Rock Classification
Geologists classify rocks into three major groups
depending on how they are formed:
Igneous rock, Sedimentary rock, and Metamorphic
rock.
There are three types of rock:
Igneous Rocks
• Formed from cooled Lava and Magma
As an Example:
Liquid lava
Frozen lava
can become
***When the lava cools and turns into a solid, it can turn into Basalt!
Igneous Rock Recipe
1. Take some Minerals &
Gasses – Mix well
2.
Place in oven (2,000 C) Quartz
Add Heat Energy & Melt
+
Biotite
+
Feldspar
3. Change Rock to Liquid
Phase (Magma)
4. Remove from heat, let it
Cool & Crystallize
(Intrusive/Extrusive)
5. Igneous Rock
Serve and Enjoy
Minerals + Heat
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There are two types of Igneous Rock:
1)Intrusive
• 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
How Intrusive Igneous Rocks Form
• When magma from below rises up, but
does not make it to the surface, the
minerals start to crystallize slowly and
form large crystals.
Volcanic
Neck
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There are two types of Igneous Rock:
2) Extrusive
• Formed on top of the crust.
• Small, hard to see crystals (cooled quickly)
• Ex: Pumice, Obsidian
***No visible crystals in either rock
How Extrusive Igneous Rocks Form
Blam!
Ash,from
Gasses,
Minerals,
• When magma
below
rises and
Volcanic
etc. don’t have
punches through,
theglass,
minerals
time to crystallize – therefore, they
types of
produce rocks with small crystals. Other
rock are
blasted out
Lava Flow
(Outside)
Lava flows out and
covers the surface
Magma
(inside)
The lava will quickly
cool into solid rock!
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• “Granite” and
“Rhyolite” form from the
same type of cooled
magma.
• If the magma cools
rapidly, smaller crystals
form and “Rhyolite”
rock is produced.
• If the magma cools
slowly, larger mineral
crystals form and the
type of rock known as
“Granite” forms.
Rhyolite: can you see crystals?
There are no visible crystals!
Granite: can you see crystals?
There are lots of visible crystals!
There are three types of rock:
Sedimentary Rock
• 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
Sedimentary Rock Recipe
Sediments, minerals
and rocks
1. Start at the
Surface
2. Weather (Break Up)
Weathering
& Erosion
Sedimentation
& Deposition
3. Erode (Carry Away)
4. Sedimentation &
Deposition
Layers of sand and sediments
Rain moves Compaction
sand, dirt, and
rocks down to the ocean
5. Compaction &
Cementation
“Cementation” (stuck
together)
Igneous rock
Sediments worn away
gather here!
Physical Properties of
Sedimentary Rock
rock that is glued to other rock
Conglomerate Rock
Notice the rounded rocks
glued in this rock. This is
from rocks that have been
eroded in a river bed.
Breccia
Take notice of small
pieces of rock stuck
together
Notice the jaded rocks glued
in this rock. This is from
rocks that have been
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involved in flash floods.
How to identify:
• 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?
Metamorphic
Rocks
• To “Morph” means to change it!
“…more than meets the eye!”
• Rocks that have changed after
being buried DEEP underground.
The heat and pressure from being
deep underground changed the
rocks.
• They were once Igneous or
Sedimentary rocks, but not
anymore.
• Has large, inter-grown crystals in
thin “bands” (Foliated) or clusters
(Non-Foliated).
Metamorphic Rock Recipe
1. Get some pre-formed rock –
Igneous or Sedimentary will do &
burry it deep underground.
2a. Add a
mild amount
of Heat
Granite
(Igneous)
2b. Squeeze to
Foliate
+ Pressure
(Not too hot)
+ Pressure
3. Cool & (Re)-Crystallize
Note: Add more heat
for Igneous Rock
4. Metamorphic Rock
+ HEAT
Gneiss (foliated)
Foliation
• Mineral crystals aligned in parallel layers.
Notice that the crystals
have been squished into
mostly straight lines.
Pressure and Heat lead to
Metamorphic Rocks
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
Crystals
line up in
mostly
straight lines
Granite=large, randomly
Gneiss=smaller, lined
located crystals becomes
up crystals
Foliated v. Non Foliated
• Geologists classify metamorphic rocks
according to the arrangement of the grains
that make up the rocks.
Foliated
Non Foliated
(curvy thin crystal lines - Gneiss)
(No lines - Quartzite)
Examples of Metamorphic
Rock:
• Gneiss:
• Schist:
• Slate:
Can you see all the
straight layers of crystals?