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Tufa

The calcareous and siliceous rock deposits of springs, lakes, or ground water.

A spongy, porous limestone formed by precipitation from evaporating spring and river waters; also known as calcareous sinter. Calcium carbonate commonly precipitates from supersaturated waters on the leaves and stems of plants growing around the springs and pools and preserves some of their plant structures. Tufa tends to be fragile and friable.

Tufa is the name for an unusual geological form of calcite rock.

Tufa is a rough, thick, rock-like calcium carbonate deposit that forms by precipitation from bodies of water with a high dissolved calcium content. Tufa is not to be confused with tuff which is volcanic. A natural rock that is a suitable decoration for Marine, Rift Valley and Brackish aquaria. Tufa is a light weight, porous rock and is formed as a calcium carbonate deposit laid down around natural mineral springs.

It is soft and easily cut and is most often used in Marine aquaria. It will work as a natural buffering agent and is easily colonised by marine algae's and macro algae's.

Wash with hosepipe thoroughly and then final rinse in a bucket of water before immersion in the aquarium as the large amount of loose material on it will create a cloudy "white out" if placed directly into the aquarium. Not suitable for most tropical freshwater aquaria.

In the ancient world, tufa's relative softness meant that it was commonly used for construction where it was available. Tufa is common in Italy, and the Romans used it for many buildings and bridges. The Servian Wall, built to defend the city of Rome in the 4th century BC, is built almost entirely from tufa. The Romans also cut tufa into small rectangular stones that they used to create walls in a pattern known as opus reticulatum.

Tufa is today occasionally shaped into a planter. Its porous consistency makes tufa ideal for alpine gardens. A concrete mixture called hypertufa is used for similar purposes.

Tufa is formed when water evaporates from lime-rich waters, leaving calcite (calcium carbonate) to crystallize, often with impurities of iron oxides (rust), which give tufa its yellow and red coloration.

Tufa is formed on cliffs, caves and quarry faces where limestone is naturally occurring. This rock can form very quickly if conditions are favourable. Plants, mosses and invertebrates often become encrusted in the calcite, and preserved as fossils.

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