From Etruscan times right up to the recent past, man has bored into the rocks of the Campiglia area to extract precious minerals.
This was the beginning of a production cycle which transformed these ores into metal. The San Silvestro Park was created to protect and make available to the public an extraordinary outdoor "archive" where archaeological research has documented traces of mining activity, piecing together fragments of the history of mining in the Val di Cornia.
Two parallel veins of porphyritic rock cross the hills and valleys (Manienti, Lanzi and Temperino) in a south-east to north-west direction. Along these veins in the limestone, minerals have been deposited forming columns sometimes hundreds of metres thick. The deposits are made up of mixed sulphides: argentiferous "galena" (lead sulphide with a high silver content), "calcopirite" (sulphides of copper and iron), blende (zinc sulphide) and in some areas also "cassiterite" (dioxide of tin). At the surface the deposits are composed of limonite (hydroxide of iron), the so-called "cappellaccio". The presence of such rich mineral resources has indisputably influenced the location and development of settlements in almost all periods, certainly from Etruscan times onwards.Despite various fluctuations and interruptions, the industrial and economic activities related to the exploitation of these resources have continued until recent times The mines exploited by the inhabitants of the castle of Rocca San Silvestro are located in the area between the Manienti Valley, Monte Rombolo and the Lanzi Valley.At present we know of fifteen mine workings associated with the period of life at the Rocca, mostly vertical shafts of varying depths and degrees of development (from a few to tens of metres deep). Rocca San Silvestro then, like other neighbouring villages (Biserno and Acquaviva), was founded along the rich metalliferous veins at the heart of an important mining region
Transformation of minerals in metal
Because they have been used together with gold as the principal components of coins, copper and silver have always been considered precious metals. The profit derived from the control of their production and commercialisation was thus considerable, as was the political importance of whoever had control of the resources for the production of local coins. In a sense Rocca San Silvestro is a concrete demonstration of the importance of the management of mineral resources and of the control of the whole metal production cycle. The settlement in fact arose with the sole and precise aim of centralising the work force and supervising all the phases of production. Within the village walls of Rocca San Silvestro a whole area has been identified which was set up for the metallurgical processing of the local minerals of copper, lead and silver. Here traces of smelting activity have been detected - waste from metal working, blocks of the fire-proof stone used in the construction of kilns, baked clay, mineral fragments, and in one lucky case even the remains of constructions used for smelting.
By studying the remains brought to light here, it has been possible to reconstruct the processes leading to the production of silver-bearing lead and copper. Outside the walls of Rocca San Silvestro the remains of an iron smelting and smithing complex have been discovered - the reduction furnace and the forge. Here the production of iron was driven by great internal demand linked to the mining and production activities of the village rather than to any commercial exploitation of iron as such