4. What are Igneous rocks?
• Igneous rocks are rocks that are formed using volcanoes
• their name is fire rocks in Latin
• The magma under the earth gets ejected out of volcanoes
and lands on the cool crust which solidifies to form types of
igneous rocks
• The larger the crystals are is the way of telling how fast the
rock has cooled
• Large crystals would mean the rock has formed slowly while
tiny or no Crystals would show that the rock has formed
faster
This is a
Link to a video whe got a lot of large cliff
information from: made of
http://www.youtube.com/watch?v=m granite
MJPVdv7D6k formed from
volcanoes
5. Basalt Rock
It forms when magma/lava gets out of a
volcano to the surface or the ocean ridge
and cools.
The basalt rock is usually gray or black and very hard
Intrusive: Cooled under the surface
It cools quickly (very small crystals) Extrusive: Cooled on the surface
It is usually extrusive but it can also be intrusive
It is the most common rock on the earths rock
There is lots of basalt on the ocean floor
It is also found on the moon and mars
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6. Obsidian Rock
• Obsidian Rocks are made by Nature Glass. The color of the
Obsidian Rock is made by the chemical makeup of lava.
• It's a extrusive Rock because it forms on the surface.
• When a Volcano erupts it spits out a lot of melted rocks.
• If the rock is silica and it cools at the right temperature that is 940c-
1080c it can turn into nature glass and then it is a Obsidian Rock.
• In the stone age the obsidian rock was a very good tool for knifes,
arrowheads, fishhooks etc. In surgery they still use the Obsidian
Rock for knifes.
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7. Granite Rocks
Granite means granum. It is made of many quarts and feldspar bits
stuck together. Granite Rocks are usually pink to gray, white or black.
Granite rocks are hard stones because it was made underground and
it cools underground. So it is a intrusive rock. Over millions of years all
those granite rocks build together a big crystal.
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