The most common sulphate mineral.
Found as both massive material, including the alabaster variety; and clear crystals, the selenite variety; and, parallel fibrous, the satin spar variety. Typically colourless to white, transparent crystals, thick tabular to lenticular, sometimes prismatic.
Gypsum is named from Greek “gypsos” – plaster, alluding to its practical use. It has been known from antiquity.
Gypsum is made up of the largest crystals in the world to date, the length of a bus, followed by people in spacesuits. They boast the Naica location in Mexico and are located about 400 meters underground. It is worth searching on the internet.