Rocks...sedimentary    igneous    metamorphic   Rocks   sedimentary    igneous    metamorphic

Rocks

There are three different types of rocks:

Igneous

Sedimentary

 Metamorphic Rock

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IGNEOUS ROCK SAMPLES

Basalt is mostly volcanic in origin...it is formed by the rapid cooling of lava.

Pumice is formed from lava that is full of gas.  As the lava cools the gas escapes leaving the rock full of holes.  Pumice floats on water because it is so light.

 

Obsidian is made when lava cools very quickly. The lava cools so quickly that no crystals can form.

When people make glass they melt silica rocks like sand and quartz then cool it rapidly by placing it in water. Obsidian is produced in nature in a similar way.

Obsidian is usually black or a very dark green, but it can also be found in an almost clear form.

Ancient people  have used obsidian for arrowheads, knives, spearheads, and cutting tools of all kinds. Today obsidian is used as a scalpel by doctors in very sensitive eye operations.

SEDIMENTARY ROCK SAMPLES

Conglomerate is made by the cementing of pebbles and other small sized rock fragments.  It is formed by river movement or ocean waves.

Halite is common table salt.  It forms where lakes or sea beds dry up.  The evaporation of the water creates the salt crystals. 

Limestone is a commonly found sedimentary rock.  It can be found all over Ohio. 

Limestone can easily be dissolved by acids. If you drop vinegar on limestone it will fizz. Put a limestone rock into a plastic jar and cover it with vinegar. Cover the jar and watch the bubbling of the calcium carbonate and also the disintegration of the rock over a few days.

 

METAMORPHIC ROCK SAMPLES

 

Marble is metamorphosed limestone or dolomite. Marble is stronger than the limestone or dolomite.  It is a good material for sink tops, counters, and statues. These rocks weather slowly.

Slate is another metamorphic rock .  It is not very hard and can be engraved easily.  It is used in chalkboards.

Gneiss is another metamorphic rock.  It is characterized by the layers and is used in building and paving.

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Rock Cycle Song
(Sing to the tune of "Row, Row, Row Your Boat")

SEDIMENTARY rock
Has been formed in layers
Often found near water sources
With fossils from decayers

Then there's IGNEOUS rock
Here since Earth was born
Molten Lava, cooled and hardened
That's how it is formed

These two types of rocks
Can also be transformed
With pressure, heat and chemicals
METAMORPHIC they'll become.

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