Specimens of selenite from Midelt, Morocco. Selenite is a variety of the mineral gypsum, it has a pearly lustre and is translucent, letting most light through but not all. It is an evaporite mineral, left over when a saline solution present millions or years ago during the Jurassic period evaporated, leaving the selenite behind. These particular samples are selenite crystal clusters and show an amalgam of multiple crystals which have merged or grown together during formation. This gives them a somewhat chaotic appearance with an aesthetic like that of a conglomeration where larger crystals are connected via numerous smaller crystals.