Adventure Mine in Greenland Township is one of the oldest in the Copper Country and entire tiers have been off-limits for a century. Owner Matt Portfleet says he has been dewatering each level slowly over time. Level Two was done about a decade ago, and now features tours. Recently, the site has been draining even further underground. Portfleet says it is like a time capsule.
Those unique conditions, featuring little oxygen and residual chemicals from when blasting was taking place, can create unique minerals found nowhere else. Portfleet says they tend to form as growth attached to copper or the predominant ore in the mine. This one is different.
Once exposed to conditions at the surface, the bright blue tends to give way to a more grayish sheen. The Adventure Mine is a seasonal site, giving tours beginning on Memorial Day weekend. Portfleet says he is being careful about opening up Level Three to the public. It is hard to reach for the average person and there are boot prints, writing on the walls, and other manmade features that are being meticulously documented.
Adventure Mine is a registered heritage site with the Keweenaw National Historical Park.