I recently listened to an interesting podcast about tunnels. It included information about how mining engineers are taught at the Colorado School of Mines, as well as coverage of the Barrick Goldstrike mine outside Elko, Nevada. I found the podcast on iTunes, but it's hard to link to individual podcasts there, so if you're interested, here's a direct link to the podcast on another site: Science Channel Podcast - Understanding Tunnels.
The Barrick Goldstrike mine is the most lucrative gold mine in the US. Barrick's website describes a global mining enterprise. The Goldstrike mine yields around 1 million ounces of gold each year. They extract the gold from the rock at a ratio of 1 ounce of gold per ton of rock. Here's a link to a Google Map showing the Goldstrike mine. Yes, it is visible in satellite imagery.