Well-established geotourism sites may develop and thrive without a formal geoheritage inventory. However, to fully recognize and protect their value, a comprehensive inventory and geodiversity assessment eventually becomes necessary. This need often arises from increasing visitor pressure or a growing demand for national or international recognition. The desire for recognition can lead to the need for conservation—and vice versa. The Lemptégy volcano, located in the Chaîne des Puys (France), exemplifies this situation. Originally a simple quarry, this monogenetic volcano has become a key geoheritage site and played a major role in the UNESCO World Heritage inscription of the Chaîne des Puys–Limagne fault. Today, Lemptégy is an award-winning geotourism destination. To support its long-term conservation and potential international recognition, it requires a complete geoheritage and geodiversity inventory that is so far lacking. In this study, we present an inventory and describe the steps taken in collaboration with site managers, visitors, and scientists to establish this and to conserve the site. The Lemptégy quarry includes 51 geosites of significant scientific, cultural, educational, and touristic interest. These sites lay the foundation for future international recognition, such an IUGS Geological Heritage site, or an IUCN Key Geoheritage area.