Grains of Sand Reveal Possible Fifth State of Matter | Wired Science | Wired.com

"“You walk on the beach, and the sand supports your weight. Pick up a handful, and it runs through your fingers, like a liquid. But you can’t walk on water,” said Jaeger. “In the top of an hourglass, sand is this strange solid. It’s at the verge of being a solid; it flows through the middle as something like a liquid, and then it’s a solid again,” he said."