An excellent topaz/bixbyite combo specimen! The bixbyite crystal has a mirror pitch-black sheen and shows sharp re-entrant angles caused by polysynthetic twinning. Bixbyite is a manganese iron oxide mineral. The iron/manganese ratio is quite variable and many specimens have almost no iron. Always a very fascinating crystal species with its seemingly complex cubic habit and modified corners/edges. AND attached to a gemmy topaz crystal! Classic Thomas Range!