Calcite
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Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale o
Rhombohedral calcite
Scalenohedral calcite
Prismatic calcite
Prismatic calcite
Gypsum
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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)