What is "grenatite"

Staurolite \Stau"ro*lite\ (st[add]"r[-o]*l[imac]t), n. [Gr. stayro`s a cross + -lite.] (Min.) A mineral of a brown to black color occurring in prismatic crystals, often twinned so as to form groups resembling a cross. It is a silicate of alumina and iron, and is generally found imbedded in mica schist. Called also granatite, and grenatite.