Gypsum
Videos
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer and as the main constituent in many forms o
Gypsum from southwest France (27 × 22 cm)
Gypsum crystals are soft enough to bend under pressure of the hand. Sample on display at Musée cantonal de géologie de Lausanne.
Large gypsum crystals in Lechuguilla Cave's "chandelier ballroom"
Gypsum crystals in the Cave of the Crystals in Mexico (person at lower right for scale)
Plaster
Videos
Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used
Stucco plaster reliefs, such as this work at the Château de Fontainebleau, were hugely influential in Northern Mannerism. A plaster low-relief decorative frieze is above it.
Applying mud plaster to an outside wall
Clay plaster base coat on split oak lath held in place with straw and manure, covered with a lime plaster top coat, Old Economy Village, Pennsylvania (1827)
Lime setting-coat on clay plaster with straw binder. Applied to hand-split lath over a timber framed wall of a brick family house at Old Economy Village, Pennsylvania