Cave clouds or mammilaries are carbonate coatings that form underwater in cave pools whose water is super-saturated with calcium carbonate. They most likely form below the water table, in the phreatic zone, rather than in perched cave pools. They form in concretional layers around projections and rocks lining the pool. In cross-section, mammilaries show rings much like in a tree or a stalagmite. In the top photo, below, clouds have formed in a now-dry pool basin. The orange staining is due to iron-rich minerals that were in the water. In the photo below, we see a cloud dippings into a pool I explored with SCUBA gear. Both photos are from Lechuguilla Cave, New Mexico, where clouds are common in lower levels.

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	Created: June 19, 1995 Last Updated: November 24, 1998 Author: Dave Bunnell