Tufa

LL Demos & Labs: Rock Profile: Tufa

This rock is from a dry lake in northern Nevada. It is the third of the calcium carbonate rocks, the others being limestone and geyserite. Tufa is formed when calcium carbonate crystallizes on an object, such as a plant stem, bone or feather in the lake. The crystals grow up and around the object and form the white to cream-colored crystal patterns.