sedimentary

Travertine (Tufa)

Chemical Limestone (CaCO3)

Hardness: 3-4 Mohs; Color: Tan, beige, white, cream; Luster: Dull, earthy; Structure: Microcrystalline, highly porous and vesicular; Specific gravity: 2.1-2.5

Hardness: 3-4 Mohs
Color: Tan, beige, white, cream
Luster: Dull, earthy

Identified July 1, 2026More sedimentary →

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Physical properties

Hardness: 3-4 Mohs; Color: Tan, beige, white, cream; Luster: Dull, earthy; Structure: Microcrystalline, highly porous and vesicular; Specific gravity: 2.1-2.5

Formation & geological history

Formed by the precipitation of calcium carbonate from mineral springs, particularly hot springs. It can also form in caves as speleothems. Formed throughout various geological ages depending on local spring activity.

Uses & applications

Commonly used in landscaping, as decorative garden stones (aquarium rocks), and as a building material when more dense. Highly valued by collectors for its unique organic texture.

Geological facts

Travertine is the material used to build the Colosseum in Rome. The 'Tufa' variety is specifically the more porous, sponge-like version often found in lake and spring environments.

Field identification & locations

Check for a highly porous, sponge-like or coral-like texture that reacts with dilute hydrochloric acid. Commonly found near hot springs (e.g., Yellowstone) or alkaline lake beds.