Glauberite
Glauberite is a monoclinic sodium calcium sulfate mineral with the formula Na2Ca(SO4)2.
It was first described in 1808 for material from the El Castellar Mine, Villarrubia de Santiago, Toledo, Castile-La Mancha, Spain. It was named for the extracted Glauber's salts after the German alchemist Johann Rudolf Glauber (1604–1668).