White Fibrous Gypsum: Selenite Satin Spar - 2 Pieces of Mineral

Though it is sometimes commonly referred to as Satin Spar, it is an allotrope of the mineral Selenite, which itself is an allotrope of Gypsum. Selenite, particularly of the Satin Spar type, which is a crystalline variety of Gypsum. It is most often observed as a silky, fibrous mineral with a translucent pearl or milky color, though it can exhibit some coloration at the "peaks" of the crystal.

Occurring on every continent, Gypsum is the most common of all sulfate minerals. It is frequently fount in salt flats and springs, and caves, and typically found with other minerals like copper ore, silver, coal, and more. When severely dehydrated, it forms anhydrite. It is possible to return to gypsum if water is reintroduced. One of the most notable occurrences of Gypsum, in the form of Selenite crystals, is the Cave of the Crystals, or Giant Crystal Cave, discovered in the year 2000 and located 300 meters below the surface of Chihuahua, Mexico. Since 1910, a series of 5 caves have been discovered, each one linked to the others: Cave of Crystals, the Queen's Eye, Candles Cave, the Ice Palace, and the Cave of Swords. Each one containing various sizes and shapes of Gypsum crystals.