lesleyite
noun
les·ley·ite
ˈleslēˌīt,
-ezl-
plural -s
: a mineral approximately K2Al8²/₃ Si4O20(OH)4 consisting of a brittle mica that is related to margarite but contains potassium
Word History
Etymology
John Lesley, Jr., 19th century American on whose farm it was found + English -ite