Historic Quarries of Ançã Limestone, A Portuguese IUGS Heritage Stone

Abstract Ançã limestone is one of the most widely used building and carving stones in Portugal, particularly valued for sculpture due to its ease of carving. Although it has been exploited since prehistoric times, its greatest use was in the 14th century, when the quarries reached their greatest splendour. The Ançã limestone (“Pedra de Ançã” in Portuguese) belongs to a level of the Ançã Formation, which occurs in the municipality of Cantanhede, about 25 km northwest of Coimbra. This formation was deposited during the Bajocian and Bathonian (Middle Jurassic) periods in the Lusitanian Basin (central-western Portugal). It is about 250 m thick and consists at the base of layers reaching ≈ 2 to ≈ 3 m of greyish micritic limestone, slightly marly, changing laterally to light grey and yellowish to whitish. This is followed by creamy white micritic limestones in beds ≈ 0.5 to ≈ 1 m thick. This work aims to compile bibliographical information on the historic quarries of the Ançã limestone, which has been designated as an IUGS Global Heritage Stone by the International Union of Geological Sciences. This will allow the correct location of the historic quarries for their enhancement and as a source of raw material for possible future restorations.