The Mineral cookeite
Cookeite (pronounced Cook-ite) is an uncommon member of the Chlorite group, and is best known for its occurrence in granite pegmatites associated with Tourmaline, where it often forms as a growth layer upon the Tourmaline. Cookeite is named in honor of Josiah Parsons Cooke Jr. (1827-1894), a Harvard University scientist who was instrumental in the measurement of atomic weights.