Travertine (Calcareous Tufa)

Physical Properties

Hardness: 3 on Mohs scale; Color: Tan, cream, white, or light brown; Luster: Vitreous to dull; Crystal structure: Trigonal (often microcrystalline); Specific Gravity: 2.71; Texture: Porous, pitted, or crystalline.

Formation & Geological History

Formed by the rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. Over time, microorganisms such as algae or moss can become trapped and decay, creating the characteristic voids/pores.

Uses & Applications

Extensively used in construction for flooring, wall cladding, and decorative facades. High-quality varieties are used in sculpture and as ornamental garden stones.

Geological Facts

Many of the most famous structures in Rome, including the Colosseum, are built primarily from travertine. It is a 'living rock' in some geyser environments where it continues to accumulate daily.

Field Identification & Locations

Identify in the field by its porous, 'honeycomb' texture and ease of scratching with a steel blade. It will react and fizz (effervesce) when exposed to a drop of diluted hydrochloric acid or even strong vinegar.

Identified on: 4/15/2026

Mode: Standard