TORONTO (miningweekly.com) – McEwen Mining has discovered a new gold zone, the Twin Domes discovery, at its fully owned El Gallo complex, in Sinaloa state, Mexico.

The company this week said the high gold grades it had encountered were “reminiscent of historical mining grades” that occurred throughout the El Gallo complex between 1800 to 1950, when about 180 000 oz of gold at grades of 20 g/t were mined.

"The historical record of high-grade in this region has always intrigued me. Due to my involvement in Goldcorp's Red Lake discovery, which became the richest gold mine in the world, I have witnessed the power that high-grade can have on a company's profitability,” chief owner Rob McEwen said.

The Twin Domes exploration highlights included an interval of 9.7 m with a grade of 8.8 g/t gold, 12.7 m grading 20.9 g/t and 1.7 m grading 112.9 g/t.

He noted exploration was the critical research and development of the mining industry.

“While the probability of making a major discovery is low, the wonderful aspect of the mining industry is the possibility of making a discovery, which is real, and often comes from an area where it is least expected.”

The Twin Domes discovery was located about 14 km west of El Gallo Phases 1 and 2.

The company said despite there being some evidence of small-scale mining, the majority of the discovery area was covered by agricultural land. Twin Domes was identified as a prospective target based on previous exploration that was completed by a predecessor company.

High-grade gold mineralisation had been identified from surface to a depth of 50 m. The known strike of the high-grade ore was about 375 m. Both core drilling and surface trenches were used to target the mineralisation.

Currently, ten trenches were being completed over the length of the mineralisation in order to gain a better understanding of the nature of the high-grade, the geology and the orientation of the veins.

The company said the exploration, including final assays, was expected to be completed by the end of April. A core drill programme was also being planned in order to target the mineralisation below 50 m, which was the current limit of the known mineralisation.

PAST PRODUCTION

The nearby city of Mocorito was built on the back of mining, beginning with the Palmarito Mineral district in the mid 1500s. Gold mining in the Magistral area (El Gallo Phase 1) began in the late 1800s, with production continuing sporadically until the 1950s.

Mining was focused on narrow, high-grade quartz veins, locally present in the structural zones.

Historic production from the Magistral mill has been estimated at 180 000 oz of gold at a grade of 20 g/t.

Several small, high-grade mines operated until the late 1990s. These mines closed when the local government-owned mill was shut down owing to low precious metal prices. The majority of these past mines are now owned by McEwen Mining and form part of the El Gallo complex.