Sierra Metals’ (TSX: SMT; TSXV: SMT; US-OTC: DBEXF) claim that its underground Yauricocha silver-copper-lead-zinc-gold mine in Peru has plenty more to give at deeper depths is proving correct.
The company with three producing mines — one in Peru and two in Mexico — announced that drilling at Yauricocha has extended mineralization below the Central Mine area, which is made up of various orebodies and remains open at depth.
Highlight intercepts came out of three different orebodies.
At Catas the best intercept began at the 105.2-metre level and returned 4.2 metres true width, with an average grade of 24% zinc and 107 grams silver.
At the Antacaca orebody, mineralization was reached at the 227-metre level and returned 2.1 metres true width grading 7.21% copper, 1.31 grams gold and 46.4 grams silver.
At the Rosaura orebody the highlight assays began at the 378-metre level and include 9.8 metres true width grading 1.14% copper and 18 grams silver.
The key to the results is Rosaura. Unlike Catas and Antacaca, which saw infill drilling, Rosaura was tested to depth and allowed Sierra to expand the orebody by another 150 metres long and 250 metres deep.
It also confirmed that Rosaura becomes more copper-dominant with depth. This pulled the average copper grade of all the drill intercepts reported up to 1.15% copper, compared to the average copper grade in its resource estimate that ranges from 0.64% to 0.72% copper.
Overall the property has proven and probable reserves of 4.1 million tonnes at 3.85 grams silver, 0.7% copper, 2.81% lead, 2.58% zinc and 0.93 gram gold.
Along with the increasing copper grade comes decreasing lead and zinc grades, which shows Rosaura is changing from a polymetallic-dominant to copper-dominant orebody that could be merging with the Catas-Antacaca orebodies at depth.
Yauricocha has high-temperature, carbonate-replacement mineralization — which makes for deposits that can have great depth extents. Sierra points out that the El Porvenir and Yauliyacu mines, which are also in Peru, have been mined to depths of 1,600 metres.
For the first six months of the year Yauricocha turned out 955,660 oz. silver, 3.9 million lb. copper, 17.7 million lb. lead, 25.1 million lb. zinc and 3,400 oz. gold, making it the company’s largest producing mine.
The good news from the drill results pairs with tragic news released just a day before from its Cusi mine in Mexico’s Chihuahau state. The company said an employee of a third-party contractor died at its Promontorio silver mine, which is part of its larger Cusi project. The worker was killed while driving a front-end loader on a surface yard near the mine when the ground gave way.
Sierra says the accident was likely caused by a ground subsidence following heavy rains.
Mexican authorities ordered Promontorio production stopped so that geophysical and hydrological surveys could be completed. Sierra says these will be finished soon and that mining will restart.
Promontorio accounts for 20% of Cusi’s silver production and 3% of Sierra Metals’ silver production. As a result the company says production will not be materially affected by the production halt.
Cusi produced 196,269 oz. silver and 326,000 lb. lead over the first half of the year.
Beyond its Yauricocha mine in Peru and Cusi mine in Mexico, Sierra also operates the Bolivar mine in Mexico.
Bolivar produced 3.9 million lb. copper, 914,000 lb. zinc and 128,099 oz. silver for the first six months of the year.
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