Silver Bull doubles Sierra Mojada silver count

VANCOUVER — Eight months, 16,700 metres of drilling and 400 channel samples later, Silver Bull Resources (SVB-T) has doubled the silver resource at its Sierra Mojada project in Coahuila, Mexico.

Silver mineralization at the property is associated with the Sierra Mojada fault zone, which extends for more than 6 km and contains two distinct targets. Silver Bull’s main focus is the Shallow Silver zone, which is a near-surface occurrence of silver oxide mineralization. The silver originally existed as sulphide mineralization but was remobilized and reconstituted as a manto-style oxide deposit.

The manto hosts an indicated resource of 71.9 million tonnes grading 72.5 grams silver per tonne and 1.38% zinc, for a contained 167.5 million oz. silver and 2.19 billion lb. zinc.

These 71.9 million tonnes of resource also host 0.34% lead and 0.08% copper. But because the geologic constraints and metallurgical responses of these elements are not as well understood as those of silver and zinc, the lead and copper resources are classified as inferred.

The updated resource represents a 103% increase in contained silver compared to the last estimate, which Silver Bull released in July 2012.

“At over 167 million oz., Sierra Mojada is now one of the largest undeveloped silver resources in Mexico,” said Silver Bull president and CEO Tim Barry in a statement. “It is also no small point to note that even though we have defined a much larger resource than previously reported, mineralization remains open on the deposit.”

Silver Bull has tracked the manto for 3.8 km along strike, and found that it averages 200 metres in width and 140 metres in thickness. More than half of the deposit delineated to date is at or near surface. From the eastern end it dips gently east. The deposit is classified as a carbonate-replacement deposit, though an intrusive source has yet to be located.

The Zinc zone, another target at Sierra Mojada, lies beneath Shallow Silver on the east side. It’s a high-grade zinc exploration target that strikes for 1.5 km. Results to date indicate the zone carries a zinc grade of 8% or better, although it hasn’t undergone a comprehensive resource estimate.

Silver Bull has been busy since it last estimated the resource within the Shallow Silver zone. Since the middle of last year the company has completed 10,000 metres of surface diamond drilling, 6,650 metres of underground diamond drilling and 400 channel samples. The underground drilling program was designed to twin historic long holes and the effort met with great success, with Silver Bull using over 40,000 metres of historic underground drill data.

History abounds at Sierra Mojada. Silver and lead were first discovered in the area in 1879. For the next hundred-plus years, zinc, silver and lead ores were mined from various spots along the fault, including within what is now the Sierra Mojada property. There are more than 50 historical mine shafts scattered along the East to West zone, many reaching more than 200 metres into the ground. Ores extracted from these shafts were generally hand-sorted, and the high-grade selection shipped to smelters in the U.S.

Silver Bull has been at work at Sierra Mojada for some time. In 1996 the company — then known as “Metalline Mining” — signed an agreement to earn into Sierra Mojada. By 2000 the company acquired full ownership of the site. The next year Penoles signed on as a joint-venture partner. The Mexican mining major completed an underground exploration program — including new underground raises, as well as diamond and percussion drilling — before walking away from the project in 2003.

In 2010 Metalline Mining merged with Dome Ventures, retaining the Metalline name until April 2011, when it changed its name to Silver Bull Resources.

Sierra Mojada is accessible by paved roads from the city of Torreon, which lies 250 km southwest.

Most of the lands around the project are used for cattle ranching, though the southeastern project border is next to a dolomite extraction and processing facility that has its own rail line.

In February Silver Bull raised US$9.2 million by selling 22.9 million units at US40¢ a piece. Each unit comprised a share and half a warrant, with each warrant exercisable at US55¢ for 18 months. The raise provided Silver Bull with enough money to complete the resource estimate, continue drilling and embark on a preliminary economic assessment at Sierra Mojada.

Silver Bull’s share price gained 1.5¢ on news of the Sierra Mojada resource to close at 38¢. The company has a 52-week trading range of 31¢ to 60¢ and has 159 million shares outstanding, with 180 million fully diluted.