How to identify Travertine

To correctly identify Travertine (Travertine), 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-brown, often with distinct banding of these colors.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to earthy, sometimes waxy on polished surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Porous, often with visible voids and cavities. Can be fibrous, concentric, or massive. Banded varieties show distinct layers.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Microcrystalline to cryptocrystalline aggregates of calcite. Individual crystals are rarely visible to the naked eye.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect rhombohedral cleavage (of its constituent calcite), but rarely observed in the rock mass due to its fine-grained, massive nature.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Associated with hot springs, cold springs, caves (forming speleothems like stalactites and stalagmites), and other environments where calcium-rich waters emerge and degas CO2, leading to CaCO3 precipitation.

Key Facts

Hardness

3 on the Mohs scale (due to calcite).

Specific Gravity

2.71 (for pure calcite, but can vary in travertine from 2.3 to 2.7 due to porosity).

Crystal System

Trigonal (for its constituent calcite).

Color

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

Luster

Dull, earthy, sometimes waxy.

Transparency

Opaque to translucent.

Fracture

Uneven to conchoidal.

Cleavage

Perfect rhombohedral (of calcite), but not typically observed in the rock mass.

Composition

Primarily calcium carbonate (CaCO3), with minor impurities like iron oxides, clay minerals, and organic matter.

Physical characteristics

• Crystal Habit: Microcrystalline to cryptocrystalline aggregates, often forming fibrous, concentric, or massive structures.
• Cleavage Type: Perfect rhombohedral (of calcite), but generally not visible in the rock.
• Fracture Type: Uneven to conchoidal.
• Tenacity: Brittle.
• Luster Type: Dull to earthy, sometimes waxy.

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