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! Read
the questions below each image. If your answer to the
question is yes, click the blue text to go to the next
step to identify the rock.
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| Matthew Nyman, TERC |
| Is the rock dark and dense? If yes, your
sample is probably basalt. Basalt may also have vesicles, holes where
volcanic gases were trapped in the cooling lava. |
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| Matthew Nyman, TERC |
| Is the rock very light compared to other
rocks of the same size? Does it break easily? If yes, your sample
is probably coal. Fossils of plants are occasionally preserved
in coal samples. |
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| Matthew Nyman, TERC |
| Is the rock dark colored with no visible rock
fragments? Break off a piece of the rock. Does it form a fine powder?
Does the rock have a fine layering? If yes, your sample is probably
shale. |
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If you have identified your sample, return to the beginning
of the rock identification
key, select another rock sample, and begin the process
over again.
If your rock sample does not have any of the features
described on this page, reexamine the rock with a hand
lens or magnifying glass. Look at the sample from all
angles. Concentrate on fresh surfaces where you might
be able to better determine the texture. Return to the
beginning of the rock identification
key and start over again.
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