What Kind of Rock Is This?
ES0610  Black Rocks

  !   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.

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.
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.
Matthew Nyman, TERC
Does the rock have abundant pores?
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.

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.