Several pieces of bornite.
a reddish-brown, soft, brittle, cubic mineral, copper iron sulfide, CuFeS, an ore of copper that tarnishes to a dark purplish color when it is fractured
Origin of borniteafter Ignaz von Born (1742-91), Austrian metallurgist
A brownish-bronze, lustrous copper ore with the composition Cu5FeS4 that tarnishes to purple when exposed to air.
Origin of borniteAfter Ignaz von Born, (1742–1791), Austrian mineralogist.