How to identify Travertine

To correctly identify Travertine (Travertine (a form of limestone)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Typically white, cream, tan, brown, or reddish; often banded or variegated.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to earthy, sometimes vitreous on fresh, dense surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Porous, often with visible voids and cavities; can be banded or layered. May feel slightly rough or gritty.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Microcrystalline to cryptocrystalline calcite, often forming botryoidal, stalactitic, or encrusting masses. Individual crystals are rarely macroscopic.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Calcite, the primary mineral, exhibits perfect rhombohedral cleavage in three directions, though this is often not apparent in the fine-grained, massive nature of travertine.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Associated with hot springs, cold springs, waterfalls, and caves where calcium-rich waters degas CO2 or evaporate, leading to CaCO3 precipitation. Often found in arid or semi-arid regions with active hydrogeological systems.

Key Facts

Hardness

3 on the Mohs scale (due to calcite).

Specific Gravity

2.3 - 2.7 g/cm³ (can vary significantly with porosity).

Crystal System

Trigonal (for calcite).

Color

White, cream, tan, brown, reddish; often banded.

Luster

Dull to earthy, sometimes vitreous.

Transparency

Opaque to translucent.

Fracture

Uneven to conchoidal.

Cleavage

Perfect rhombohedral (for calcite, but often not visible in massive travertine).

Composition

Primarily calcium carbonate (CaCO3), with minor impurities.

Physical characteristics

• Crystal Habit: Massive, encrusting, botryoidal, stalactitic, often porous and layered.
• Cleavage Type: Perfect rhombohedral (of constituent calcite).
• Fracture Type: Uneven to conchoidal.
• Tenacity: Brittle.
• Luster Type: Dull, earthy, sometimes vitreous.

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