Ferdinando and Carolina Caves, Pulo di Molfetta, Molfetta, Metropolitan City of Bari, Apulia, Italyi

Regional Level Types
Ferdinando and Carolina Caves	Group of Caves
Pulo di Molfetta	Depression
Molfetta	Municipality
Metropolitan City of Bari	Metropolitan City
Apulia	Region
Italy	- not defined -

Ancient caves, both natural and partially man-made, located at Pulo di Molfetta and exploited in the Bourbonic period (18th and 19th century) for extracting saltpetre (saltpeter), used for the manufacture of gunpowder. They have been named after Ferdinand IV of Bourbon, king of Neaples, and his wife Maria Carolina, who visited this site in 1790.
Pulo is an ovoidal karstic depression, attaining about 600 m in perimeter and 30 m in depth, situated 2 km SW of Molfetta. The vertical faces of this dolina, consisting of Cretaceous limestones and originated from the collapse of a large underground cavity, are scatterd with numerous caves. The caves have a natural origin, although some of them had been partly modified by man throughout the centuries. All caves are free of calcium carbonate concretions, because of the absence of dripping water.
At the bottom of the dolina there are the remains of the Bourbonic factory, where saltpeter was concentrated and refined.

Niter in Pulo di Molfetta was discovered by Abbot Giuseppe Maria Giovene (1753 -1837), who published his observations on the white mineral of the caves and corresponded with some naturalists of the era (Fortis, Dondi-Orologio), who visited the site and further investigated the mineral (Pizzaleo, 2001).
Historically the name niter, actually potassium nitrate, “has been applied to a variety of other minerals and chemical compounds, including sodium nitrate (the mineral nitratine), sodium carbonate (the mineral natron) and potassium carbonate” (Ciriotti et al., 2009).
These early analyses by Giovene, Fortis and Dondi-Orologio are probably the first analyses on a natural occurrence of niter and, according to Ciriotti et al. (2009), it is possible that the Pulo di Molfetta is the type locality of niter.
Zimmerman (1789) identified four different nitrates admixed in the white efflorescences of the caves, i.e. "nitrum terra mineralisatum" (niter), "nitrum nudum nativum" (nitratine), "nitrum terra involutum" (nitromagnesite), and "nitrum basi calcarea" (nitrocalcite).
A recent study on samples of white efflorescences with various macroscopic morphology (veillike, hard compact, sugar-like, and drusy aggregates) showed that they always consist of niter in association with minimal amounts of other minerals, such as gypsum, halite, sylvite, and calcite (Laviano, 2007).

Other Regions, Features and Areas containing this locality

References