What Kind of Rock Is This?
ES0610  Porous Rocks
Matthew Nyman, TERC

Is the rock light colored and very light in weight compared to other rocks of the same size? If yes, your rock is probably pumice. Pumice is mostly trapped air and may actually float on water!

Matthew Nyman, TERC

Is the rock dark or reddish colored and fairly light in weight compared to other rocks of the same size? If yes, your rock is probably scoria. Scoria is frequently used in gas barbecue grills to spread heat from the burner more evenly.

Matthew Nyman, TERC
Is the rock dark colored and fairly heavy compared to other rocks of the same size? If yes, your rock is probably basalt. Basalt may also have vesicles, holes where volcanic gases were trapped in the cooling lava.

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.