eastonite
noun
eas·ton·ite
ˈēstəˌnīt
plural -s
often capitalized
: a mineral K2Mg5AlSi5Al3O20(OH)4 consisting of basic silicate of potassium, aluminum, and magnesium and being an end-member of the biotite system
Word History
Etymology
Easton, city in eastern Pennsylvania, its locality + English -ite