STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY
Gypsum crystals. Coloured scanning electron micrograph (SEM) of crystals of calcium sulphate dihydrate, or gypsum. Gypsum is used as plaster of Paris. It is a white rock that is ground to a fine powder and then heated until it has lost about three quarters of its water content. When this powder is mixed with water the paste dries to a rock-hard finish.
Model release not required. Property release not required.