Hydromagnesite Balloons, manganese, the unseen. See what Jewel Cave National Monuments caving tours are all about. At this time the only known video footage to exist of these spectacular balloons.
This is the second of two videos containing the hydromagnesite balloons done for Jewel Cave National Monument in Custer South Dakota.
There are only a half dozen known caves in the world to contain this natural formation. These videos are the only known footage of them.
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