On the Big Island in Hawaii, you will find this black sand beach. I love the contrast in this picture with the blue sky, green palm trees, and the black sand. According to wikipedia “Lava, erupting onto a shallow sea floor or flowing into the sea from land, may cool so rapidly that it shatters into sand and rubble. The result is the production of huge amounts of fragmental volcanic debris. The famous ‘black sand’ beaches of Hawaii, such as Punaluu Black Sand Beach, were created virtually instantaneously by the violent interaction between hot lava and sea water.”
I believe I was at the Punaluu Black Sand Beach in this photo.