Geosciences and engineering of Lungro rock salt: unveiling Italy’s longest-lived underground mining site in Calabria

The Lungro area is renowned for the presence of the longest-lived Italian underground rock salt mine, exploited almost continuously from ancient times until 1978. The history of mining activity is documented since the Middle Ages, although evidence suggests that salt production by near-surface excavation dates to the Greek and Roman civilization or even to prehistoric times. During the Middle Ages, mining methods were aimed to the maximum profit, and the mine, rather than being rationally developed, was deepened along the vertical, following the winding path of higher quality salt layers. This approach led to problems such as of rock instability, inadequate ventilation and water infiltration arose (Galli, 1828), that characterized this mine up to its recent abandonment. Following the Napoleonic invasion of the Kingdom of Naples (1806-1815), the modernizing spirit of the new rulers was aimed to reorganize the feudal administration and diminish most of the rights and privileges of the old nobility. As part of this process, mines were nationalized, and the mineral resources of Calabria attracted the interest of the French government. In 1811 the naturalist and geologist Giuseppe Melograni published a comprehensive report on the site, rich in geological considerations, technical descriptions, geometrical surveys, and practical recommendations for a modern and rational mining operations (Melograni, 1822). Concurrently, Pietro Pulli, Inspector General of the Kingdom, was commissioned to provide information on the economic and social conditions existing in Lungro (Pulli, 1813). By the mid-19th century, the mine, with its four production levels, a ventilation shaft and a complex tunneling network, was an important industrial enterprise, with over 400 miners, alongside a technical and administrative staff, a number comparable only to the steam spinning mills of Villa San Giovanni (Reggio di Calabria). In 1879, Torquato Taramelli visited Lungro and the surrounding area during a field trip to Calabria, and provided invaluable stratigraphic and paleontological observations, both still very unknown at the time (Taramelli, 1880). His report contains also a precious first-hand description of the bad working conditions he experienced inside the mine. Although partially renovated at the end of the 19th century, both in its internal structure and in work organization, the mine decline began in the early 1900s. This decline accelerated as the Italian government estimated that sea salt produced in Sicily was cheaper than rock salt from Lungro. Consequently, a “slow death” approach was used, gradually decreasing exploitation of the deposit until all workers retired, without layoffs but also without new hires. Miners access to the underground was never solved: still in the 1970’s, two of the eight working hours of the daily shift were lost to descend into and ascend from the mine, as there were over 2000 steps to walk. Poor mining methods persisted throughout the 20th century, culminating in its final abandonment in 1978.