Mining technologies at deep level in Antiquity : The Laurion mines (Attica, Greece)
Résumé
The silver mines of Laurion, located 35 km south-east of Athens, were the most important mining district of ancient Greece in the fi fth and fourth century BC. This source of wealth highly contributed to the power of Athens. The Lavreotiki peninsula is situated in the northwestern Attic-Cycladic metamorphic complex; it belongs to the median metamorphic belt of the Hellenides and is built up of various alpine tectonic units. In this context, rich deposits of zinc, lead and silver have concentrated. The ancient miners managed to separate lead and silver from ores as galena and cerussite. It followed that they developed an impressive complex of shafts (Herbach et al. in this conference), and mining network through marbles and micaschists up to deep level. Mining, and metallurgical remains cover about 120 km2. Except during the modern mining phases, underground deep explorations have never been realised. In the south part of the district, geological mapping, fi eld investigations, underground explorations, topographic survey (surface, shafts and galleries) lead to a revision of the lithostratigraphic subdivision, conduce to specify the geometry of the enclosing beds of mineralizations and provide substantial details about ancient mining technologies. Thus, implementation of different technical processes for stoping, ventilation and extraction was essential to work such ore deposits. In hard rock as marble, progress in the shafts, galleries and stopes was almost exclusively performed using hammer and pick. Several working methods in opening operations and stoping, determined by the study of toolmarks seem to prevail to reach and extract lead and silver ore deposits. The exploration of shafts reaching up to 100 meters deep reveals exceptional and absolutely vertical mining works, models of perfection and engineering. They are actually the only one known remains in the Ancient mediterranean basin, where vertical shafts reach underground networks dug down deep on several levels. These mining works obviously required a high level of engineering and management. The sinking of deep vertical shafts into marble and micaschists formations was quite well executed by miners during Antiquity. In addition to the ventilation, they were able to control and perfect mining processes adapted to a singular geological and geomorphologic context while exploring a very large area at deep levels.