sedimentary

Travertine (Tufa)

Chemical Limestone (CaCO3)

Hardness: 3-4 Mohs; Color: Tan, beige, brown; Luster: Dull to earthy; Crystal Structure: Trigonal (microcrystalline); Cleavage: Perfect rhombohedral in calcite crystals, generally lacks visible cleavage in porous form; Specific Gravity: 2.5-2.7

Hardness: 3-4 Mohs
Color: Tan, beige, brown
Luster: Dull to earthy

Identified June 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the precipitation of calcium carbonate from mineral springs, hot springs, or geologically around lake shores where water evaporates. It often forms rapidly, trapping organic matter and creating a porous, 'vuggy' texture.

Uses & applications

Used extensively in construction as flooring, wall cladding, and pavers. Also popular in aquarium landscaping and garden decor as 'holy rock.'

Geological facts

Travertine is the material used to build the Colosseum in Rome. The porous version with large voids, as seen in this specimen, is often referred specifically as 'Tufa' when formed in cold freshwater environments.

Field identification & locations

Identify in the field by its characteristic holes (vugs), porous texture, and responsiveness to dilute hydrochloric acid (it will fizz). Commonly found in karst landscapes and near geothermal areas like Yellowstone.