Travertenlerin oluşumu, özellikle sıcak su kaynaklarının bulunduğu bölgelerde meydana gelen karmaşık bir süreçtir. Bu mineral, suyun içindeki kalsiyum karbonatın belirli koşullar altında katı hale gelmesiyle oluşur. Genel olarak, yer altı suyu, çeşitli kimyasal reaksiyonlar ve fiziksel süreçler sonucunda kalsiyum ve karbonat bileşenlerini ayrıştırarak travertenin temel yapı taşlarını oluşturur.

Travertine forms when calcium carbonate separates from water through evaporation, typically in areas with active springs or geothermal activity. The process occurs in several steps:

• Dissolution of limestone. Groundwater containing dissolved carbon dioxide comes in contact with limestone, dissolving some of it as soluble calcium bicarbonate.
• Precipitation of calcium carbonate. As the concentration of dissolved calcium bicarbonate builds up, it begins to revert to calcium carbonate, water, and carbon dioxide. When carbon dioxide escapes from the mineral-rich water, the solution becomes unstable, and calcium carbonate begins to solidify.
• Deposition. This process creates thin layers of stone that accumulate over time, forming the structure of travertine.
• Formation of pores. Pores are formed by gas bubbles trapped during the deposition process, as well as organic materials that decompose over time.

Travertine can also form in caves, where it creates rock formations called stalactites and stalagmites.