Bonanza is back! No, I'm not talking about reruns of the classic American television series, but about the discovery of "bonanza" gold grades in Red Lake, Ontario.

The Red Lake region has already produced 20 million ounces of gold historically, and yielded an impressive 700,000 ounces for Goldcorp (NYSE:GG) in 2007. It's also seen rapid consolidation, as Goldcorp snatched up explorer Gold Eagle Mines just weeks after a strategic investment by Agnico-Eagle Mines (NYSE:AEM).

Meanwhile, junior gold explorer Rubicon Minerals (AMEX:RBY) has seen a 36% leap in its shares since its Tuesday announcement of "bonanza" grade gold from its Phoenix Gold Project in Red Lake. It could be a huge jackpot indeed if the reports about ounces of gold per ton of ore pan out. To understand the magnitude of the assay results, we first need something to compare them to.

According to recent assay results, the Bruce Channel Discovery by Gold Eagle Mines, which generated all the interest from those big-hitters, sports gold grades as high as 1.39 ounces of gold per ton of ore. It's important to note that assay results from one exploratory drilling site can differ greatly from average grades over an entire mine. For example, although Goldcorp mines a particular mineral-rich vein at Red Lake with a grade of 2 ounces of gold per ton, the average grade over the entire 4.5 million ounces in reserve is more like 0.60 ounces per ton.

For further comparison, reserves at Barrick Gold's (NYSE:ABX) flagship Goldstrike Mine in Nevada average 0.15 ounces per ton. At the Yanacocha Mine in Peru, run by Newmont Mining (NYSE:NEM) in a joint venture with Buenaventura (NYSE:BVN), the 14.2 million ounces in reserves are expected to average 0.024 ounces per ton. At these grades, these mines are not only economically viable, but are considered world-class deposits. So how does Rubicon's Phoenix Gold project stack up?

Well, we can't speak about total amounts of gold or average grades at Phoenix because the resource is still being defined. One drill hole, though, has encountered gold at 26 ounces per ton! Another hole previously yielded 10.55 ounces per ton. These are huge concentrations that suggest that Goldcorp founder and former CEO Rob McEwen, who owns 31% of Rubicon, still has the golden touch. It's a long and challenging road from resource discovery to gold production, but when you find a bonanza, I believe those potholes have a way of getting filled in.

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