Emerald Isle Property: History

HISTORY OF EXPLORATION AND MINING

Old mine buildings (mid-1900’s) and tailings from El Paso Copper operations.  Looking northeasterly with Cerbat Mountains in background.

Historic mining activities in the Wallapai district of northern Arizona date back to the early 1860s, mostly for silver and gold within oxidized portions of veins. With the turn of the 20th Century mining companies started to explore for base metals. From 1917 to 1943 the property was worked at various times. From 1944 to 1948 a 300 tpd copper leaching plant was in operation. About 55,000 tons of copper were reported to have been recovered. Results from this operation reportedly indicated leach recoveries in the order of 80% from “ore” with a head grade of 1% Cu. Acid consumption was in excess of 10 lbs. of acid per pound of copper produced.

During the past half-century a considerable amount of work was done by El Paso Natural Gas Company (El Paso), Arimetco, Inc. (Arimetco) and contractors. These include completion of some 17,200 ft. of drilling in 90 rotary drill holes. In addition, some 8,600 ft. of drilling in 45 reverse circulation drill (RCD) holes were also completed by Holcorp. Past work also included development of the present open pit, and reported production of some 1.4 million tons (1.27 million tonnes) of oxide material averaging about 1% Cu.

During the 1970s, El Paso also carried out blasting and in-situ leaching at the bottom of the open pit. This was done in conjunction with the United States Bureau of Mines (now the United States Geological Services). Results of this test, however, were not encouraging.

In 1980, TSC Enterprises, Inc. (TSC) acquired the Emerald Isle Property from El Paso, but the property remained inactive. In 1987, TSC was acquired by Arimetco, Inc. (Arimetco) and produced some 100,300 lbs. of cement copper (82% Cu) from the open pit. In 1992, TSC commissioned an 8,000 lbs./day SX-EW plant and reportedly produced 1,152,663 lbs. of copper from 162,565 tons with an average head grade of 0.57% total copper (TCu). These figures equate to a copper recovery of 62%. Due to the prevailing low copper price at that time, however, the plant was shut down in September 1993. In 2003, TSC changed its name to Western Consolidated Resources (Western).