What Kind of Rock Is This?
ES0610  Sedimentary Rocks

Rub the rock with your fingers. Does it feel gritty? Are the rock fragments sand sized? If yes, your sample is probably sandstone.

Are the rock fragments pebble sized or larger? If yes, your sample is probably conglomerate.

 

Is the rock chalky or are the fragments marine fossils such as shells? If yes, your sample may be limestone. Click here to go to the acid test.

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.

Matthew Nyman, TERC

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.