sedimentary

Travertine

Calcareous Tufa (CaCO3)

Hardness: 3-4 (Mohs); Color: Tan, beige, creamy white; Luster: Dull to earthy; Structure: Microcrystalline with pits/voids; Cleavage: None (friable/massive); Specific Gravity: 2.4-2.7

Hardness: 3-4 (Mohs)
Color: Tan, beige, creamy white
Luster: Dull to earthy

Identified March 8, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (Mohs); Color: Tan, beige, creamy white; Luster: Dull to earthy; Structure: Microcrystalline with pits/voids; Cleavage: None (friable/massive); Specific Gravity: 2.4-2.7

Formation & geological history

Formed by the precipitation of calcium carbonate from mineral springs, particularly hot springs. It often accumulates in terraced deposits or as tufa around lake shores. Ages vary from Holocene to Paleozoic depending on the deposit location.

Uses & applications

Extensively used in construction for flooring, wall cladding, and pavers. Historically used in Roman architecture (e.g., the Colosseum). Also used for aquarium decor and garden landscaping.

Geological facts

The pitted appearance is often caused by the escape of carbon dioxide gas bubbles during the rapid precipitation process. It is a terrestrial sedimentary rock, unlike most limestones which are marine.

Field identification & locations

Identify in the field by its porous, vuggy texture and its reaction (bubbling) to weak acids like vinegar or HCl. Found commonly in Italy, Turkey, Mexico, and the USA (Yellowstone). Collectors should look for unique banded patterns or fossilized plant impressions.