Made of limestone, tufa forms as a byproduct of the precipitation of carbonate minerals from surrounding water. When water from heated underwater hot springs rich in calcium meet with the carbonates in lake water, the result is calcium carbonate, also known as limestone.

What is tufa made out of?

Tufa, often called calcareous tufa, is a sedi- mentary rock composed of calcium car- bonate (limestone) deposited as calcite, aragonite, or high-magnesium calcite. The hard, dense variety of tufa is travertine.

How long does tufa take to form?

Tufa towers are forming today, under the water’s surface. 2. The process is rapid: up to an inch can be added in 1 day (though this happens only occasionally) and all of the formations we saw are only a few centuries old.