granitite

noun

1. (countable, uncountable)Any of various types of granite containing a high percentage of biotite.

   “In several places, notably on the road to Coffin's Beach, and in the vicinity of Bond's Hill, on the west side of Squam River, opposite the city of Gloucester, the diorite is in such a position as to indicate that it is included in the granitite.”

   “For some time the presence of the diorite was unperceived, and it was considered a mere fine grained variation of the Cape Ann granitite.”

   “Microscopically the muscovite granites exhibit an absence of biotite, and generally less magnetite and more quartz than the true granites. The granitites in the hand-specimen are somewhat darker in colour than the true granites,”