As the helicopter circles the Lluvia de Oro mining site, deep within Mexico's Sierra Madre mountains, it's impossible not to feel a sense of history. Nestled in between 8,000 foot-high mountain peaks, Lluvia de Oro was the site of one of history's highest grade mines in the early 20th century.
While the site's lain largely fallow for the past 80 years, the crumbling mine workings have in recent months begun to show signs of life, thanks to a new exploration programme from West Timmins Mining [TSX:WTM].
A recent site visit to the remote site was a strange temporal journey – both a step back in time to Mexico's golden age of mining, and a look toward the future at one firm's dreams of striking it rich.
A Step Back in Time
Lluvia de Oro, which translates as Rain of Gold, was one of Mexico's highest grade historic producers – churning out precious metals from a deposit with grades as high as 95 g/t gold and 865 g/t silver during the first two decades of the 20th century.
After the easily found, highest grade sections of the mine were exhausted by 1915, Lluvia de Oro was the subject of brief 'pillar recovery' mining operation in the 1950s, and some limited exploration by the Mexican government in the 1990s. From the early 1980s through 2007 it was held by the government as part of its National Mineral Reserve.
Lluvia de Oro
The site has long been near to the heart of Peter Megaw, a geologist who's been exploring this region of Mexico for more than two decades and helped found both West Timmins and Mag Silver [AMEX:MVG; TSX:MAG]. As a member of West Timmins' board of advisors, Megaw was instrumental in securing the Lluvia De Oro property just over a year ago.
During a ride down to the mine site in the back of pickup truck from the nearby helicopter landing pad, Megaw explained his fascination with the property.
It's a million and a half ounce producer that's never had [modern exploration]. No one has ever tried to find the source of this system – and that's what we're trying to do. We're not just here to pick the walls and get what the old-timers left behind.
In early 2007, Megaw went up against Mexican mining titan Peñoles, which owns the bulk of the land surrounding Lluvia de Oro, for the exploration rights to the property. In a curious closed door auction, representatives for both Timmins and Peñoles were required to place their cell phones in a closed desk drawer – so that they could not call their bosses to ask for money – before setting down to bid.
As we got towards $600,000, our guys began to figure out that they [Peñoles] were reaching their limit, Megaw noted. Timmins won the exploration rights for $610,000.
I've been watching this property for the past 17 years, Megaw added, noting that he was unable to gain access to it during a prior exploration boom in the mid-1990s.
He now has it.
Modern Exploration Meets Historic Mining
While Timmins exploration programme just began on Lluvia de Oro late last year, it's already showing signs of promise. An early stream sediment sampling found multiple samples in excess of 1 g/t gold, and more recently the firm reported finding a sizable anomaly 1000 to 3000 metres north of the historic mine workings that includes new, high-grade surface outcrops of 13.10 g/t gold and 402 g/t silver.
The company plans to continue sampling and mapping the property through the summer, and potentially start drilling in the fall after the rainy season – which makes the high mountain roads un-navigable for heavy equipment – has passed.
A surface trenching programme by the Mexican government in the 1990s revealed only moderate levels of gold and silver around the property. However, Megaw noted that assays from these samples were incorrectly done, and offers as proof the much higher gold and silver values reported by a re-assaying done by a third party laboratory of some of the same samples.
A Journey Underground
The historic mill workings and developing modern mining camp at Lluvia de Oro sits in a small valley, surrounded on three sides by nearly sheer cliffs. A 15-minute walk around the side of one cliff face leads to the entrance to the historic mining site. While not necessarily the major focus of exploration, given the surprising efficiency of early-20th century mining, a step into the mine is itself a unique journey into a historic period in mineral extraction.
A large initial chamber and visitor-friendly lighting welcomes us to the normally pitch-black space, while a warped wooden footbridge left over from some unknown period leads out into an empty void overlooking a deep cavern. Further in, a twisting catacomb of tunnels leads deep into the mountain side, occasionally punctuated by bulbous galleries where high-grade ore was mined. The most noticeable thing is the cool breeze that's constantly present, alerting visitors to the fact that the tunnel goes straight through to the other side of the mountain some 600 metres in the murky black distance.
All told, it's an awe-inspiring sight, and a unique testimony to the fascinating history of mining in Mexico.
While exploration is in the very early stages at Lluvia de Oro, and the rough terrain is sure to present some unique challenges to Timmins, it's hard not to find Megaw's enthusiasm for the under-explored property infectious.
After spending years exploring the Sierra Madres and helping to build successful mining companies, Megaw seems undaunted by the challenges presented by Lluvia de Oro. After 17 years of waiting to get on site, he's ready to see what develops at the property.