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The Rock Cycle
Rocks don't form into
the three types of rocks and stay there. The Earth is constantly
changing and in motion. The rock cycle demonstrates how a rock can
start out as one type and change into another.

Any rock can be taken
through the cycle. For example, I will start with granite (remember,
granite is intrusive).
As granite is exposed
on the Earth's surface it starts to weather. Rain and snow and wind
all work on breaking the granite down into smaller pieces. As the
granite is weathered, the minerals that make up granite-quartz,
feldspar, and mica all break down out of the rock.
The mica and feldspar
turn to clay minerals and are deposited close to the granite. The
quartz is much stronger. It finely ends up along rivers and lakes or
oceans as sand. The sand builds up thick layers so the sand on the
bottom becomes sandstone. As the sandstone is pressurized it becomes
quartzite.
So now lets say the
quartzite is exposed to the surface due to weathering. As the quartzite
starts to weather, it will become sandstone and can start the process
over again. Or the quartzite can be buried in the Earth's crust and go
into the mantle to become molten rock which can become granite again.
Not all rocks go
through the rock cycle. And not all rocks go through all the stages.
For example: a sedimentary rock may weather again and become a new
sedimentary rock.
Suggested Classroom Project
Collect three(3) of
each type of rock: igneous, metamorphic & sedimentary. Explain how
each type of rock forms.
Bonus Question: What is the difference between intrusive and extrusive
igneous rock?
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IGNEOUS: |
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Intrusive: |
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Granite |
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Extrusive: |
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Rhyolite |
Obsidian |
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Basalt |
Scoria |
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Pumice |
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SEDIMENTARY: |
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Sandstone |
Limestone |
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Conglomerate |
Slate |
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Shale |
Chert |
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METAMORPHIC: |
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Schist |
Gniess |
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Serpentinite |
Marble |
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These rocks can be displayed in a number of ways. Glue rocks to the
bottom of a cardboard box or put each rock in its own plastic bag and
label. We recommend keeping track of the locality where each rock is
found. A specimen is much more interesting and scientifically more
valuable if the locality is known.
For
additional questions, please contact me at
rockshop@rocks4u.com.
Rick Dalrymple
Suggested Classroom Project

Check out Ms. Stupelli's 5th
Grade Rock Tumbling Project at:
rocktumblers.blogspot.com/2005_12_10_rocktumblers_archive.html
rocktumblers.blogspot.com/2005_12_19_rocktumblers_archive.html
Suggested Classroom Project
What are UV Minerals?
Minerals that fluoresce under Ultra Violet Light. See for
yourself!

Minerals under Ordinary Light

Minerals under Short Wave UV Light
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