It is the worldwide occurrence of mineral deposits of the Banded Iron Formation (BIF) of Precambrian age with its affiliates in terms of Mn and Au.
Gold-bearing BIFs may apart from native gold, contain As, Cu, Zn, Pb, Sb and Te, too. It is very well predictable in terms of extension and thickness and of very-low to medium metamoprhic grade
The metamorphism of limestone with contemporaneous intrusion of granitic dikes formed partly by replacement, the rich lead-silver deposits at Laurium in southern Greece which provided the money to build the Parthenon and the fleet that fought the Invaders at Salamis.