sedimentary
Travertine (Tufa)
Chemical Sedimentary Rock / Travertine (CaCO3)
Hardness: 3 (Mohs scale); Color: Tan, beige, cream; Luster: Dull to pearly; Structure: Highly porous (vesicular/vuggy); Composition: Calcium carbonate (Calcite/Aragonite)
- Hardness
- 3 (Mohs scale)
- Color
- Tan, beige, cream
- Luster
- Dull to pearly
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Physical properties
Hardness: 3 (Mohs scale); Color: Tan, beige, cream; Luster: Dull to pearly; Structure: Highly porous (vesicular/vuggy); Composition: Calcium carbonate (Calcite/Aragonite)
Formation & geological history
Formed by the rapid precipitation of calcium carbonate from mineral springs, particularly hot springs. The highly porous 'tufa' variety often forms in ambient temperature waters with plants and algae, whose decay leaves behind the large voids visible in the specimen.
Uses & applications
Primarily used in construction for floor tiles, wall cladding, and pavers. More porous varieties like this specimen are often used for aquascaping in fish tanks or as decorative garden stone.
Geological facts
Travertine was used to build the Colosseum in Rome. The holes are caused by gas bubbles and organic material (like moss or twigs) being trapped and then rotting away as the stone hardens over time.
Field identification & locations
Identified by its distinctive porous, 'Swiss cheese' texture and tan color. It will react and fizz if a drop of vinegar (weak acid) is applied. Found worldwide near geothermal areas and limestone caves.
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