The earliest copper mines were fissure deposits, like the Cliff vein, and the Delaware fissure. But the bigger and enduring mines were “lodes” that followed particular horizons. Only certain lode horizons in the Portage Lake Lavas were mineralized. There were some mines like the Quincy which were mineralized lava flow tops, while others like those in Calumet, were Conglomerate ore bodies. The Delaware Mine is in the Allouez Conglomerate, one of two commonly mined interflow conglomerates. We can walk through the mines upper levels and see the water table and a stoped area.
