pentahydrite
/ˌpɛntəˈhʌɪdrʌɪt/Mineralogy
noun
A mineral which consists of magnesium sulphate pentahydrate, MgSO4.5H2O, occurs as massive, granular, white to light blue crystals, and belongs to the triclinic crystal system.
Origin
1950s. From pentahydr- + -ite; coined by C. Frondel in 1948.