Hilgardite
From Wikipedia, the free encyclopedia
Hilgardite is a mineral with the chemical formula Ca2B5O9Cl·H2O. It is named after Eugene W. Hilgard. It is found in Germany and Louisiana. It is transparent and has vitreous luster. It is colorless, but leaves a white streak. It has a triclinic crystal system. It is rated 5 on the Mohs Scale.