Mining in European History and its Impact on Environment and Human Societies –

Proceedings for the 2nd Mining in European History Conference

of the FZ HiMAT, 7.-10. November 2012, Innsbruck

Editors:Peter Anreiter

Klaus BrandstätterGert Goldenberg

Klaus HankeWalter LeitnerKurt Nicolussi

Klaus OegglErnst Pernicka

Veronika SchafferThomas StöllnerGerhard Tomedi

Peter Tropper

© innsbruck university press, 2013Universität Innsbruck1st edition.All rights reserved.Coverphotos: © Mag.a Barbara Viehweider, Mag.a Caroline O. Grutsch, DI Michael Moser, Andreas BlaiknerEditorial office, Layout: Mag.a Veronika Schafferwww.uibk.ac.at/iupISBN 978-3-902936-18-9

Forschungszentrum (FZ) HiMAT Die Geschichte des Bergbaus in Tirol und seinen angrenzenden Gebieten – Auswirkungen auf Umwelt und GesellschaftUniversität Innsbruck

The research centre HiMAT is supported by the University of Innsbruck, the Province Tyrol, the Autonomous Province of Bozen-South Tyrol, the Province Vorarlberg, the Province Salzburg and the Department of culture of the Province Tyrol.

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Mining technologies at deep level in Antiquity: The Laurion mines (Attica, Greece)Patrick Rosenthal1, Denis Morin2, Richard Herbach2,3, Adonis Photiades4, Serge Delpech5, Denis Jacquemot5 & Lionel Fadin6

1 UMR CNRS 6249 Laboratoire Chrono-environnement, Université de Franche-Comté, France2 UMR CNRS 5608 Laboratoire TRACES, Travaux et Recherches Archéologiques sur les Cultures, les Espaces et les Sociétés, Université de Toulouse-le-Mirail, France3 Université de Technologie de Belfort-Montbéliard (UTBM), France4 Institute of Geology and Mineral Exploration (IGME), Attica, Greece5 Equipe Interdisciplinaire d’Etudes et de Recherches Archéologiques sur les Mines Anciennes et le Patri-moine Industriel (ERMINA), Besançon, France6 French school at Athens (EFA), Greece

The silver mines of Laurion (Attica, Greece) were the most important mining district of ancient Greece during the fifth and fourth century AC. This source of wealth highly contributed to the power of Athens (Ardaillon, 1987; Conophagos, 1980; Domergue, 2008). Mining, and metallur-gical remains were scattered on an area extending almost 150km2.

In 1865 started the mining resumption of Laurion, first by the treatment of the ancient slags and waste (Ledoux, 1874) and quickly by reopening of the mines (Cordella, 1869; Cambrésy, 1889; Conophagos, 1980). Therefore, more than one hundred years of extracting of lead, zinc and silver singularly led to the rediscovery, to the use, and sometimes to the destruction of ancient works. Contemporary mining works closed in 1977. Since these last operating phases, these researches as described are the first systematic underground deep exploration and survey ever carried out between Spitharopoussi plateau and Megala Pefka valley (Fig. 1).

Geological mapping, field investigation, and survey (surface, shafts and galleries), and under-ground explorations lead to a revision of the lithostratigraphic subdivision (Morin & Photiades, 2005). This new data allows to specify the geometry of the enclosing beds (Fig. 2) and provides substantial details about ancient mining technologies.

GeologyThe Lavreotiki peninsula is located 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 (Photiades & Carras, 2002; Photiades et al., 2004). In this context, rich deposits of zinc, lead and silver have concentrated (Leleu, 1966; Voudouris et al., 2008; Bonsall, 2011; Berger et al., 2013).

The study area is mainly composed of metamorphic rocks with (bottom to top) Lower and Upper Kamariza marbles (80 to 100m thick) interpreted as opposite Triassic-lower Jurassic limbs of a

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Fig. 1: Location of Laurion silver district and study area.

Fig. 2: Geological cross-section with mineralized contacts, ancient mining shafts and networks.

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recumbent syncline with hinge made of Jurassic Kamariza schist (15 to 40m); the Transgres-sive calcareous formation (Jurassic) overlaying locally upper Kamariza marble and finally, the Laurion blueschist unit (Jurassic) with meta-ophiolite overthrusted on previous layers (Fig. 2).

The ancient miners managed to separate lead and silver from ores as galena and cerussite (Conophagos, 1980). They developed an impressive complex of absolutely vertical shafts (Morin et al., 2013) and mining network through marbles and micaschists up to deep level.

An upper ore occurrence is related to the tectonic contact between the Laurion blueschist unit and the Transgressive calcareous formation or the Upper Kamariza marble. It includes oxides with calcite-fluorite matrix and lead, zinc and silver sulphides speckled in porous carbonate of the Transgressive calcareous formation. It has been called first contact by the nineteenth century miners.

Near the contact between Upper Kamariza marble and Kamariza schist, a cerussite (PbCO3) and smithsonite (ZnCO3) occurrence in a more or less brecciated matrix with fluorite and quartz, forms the so called second contact of the nineteenth century miners.

A lower occurrence connected with the interface between Kamariza schist and Lower Kamariza marble contains filled cavities with cerussite and iron oxide in a calcite-fluorite-quartz matrix, that is the so called third contact of the nineteenth century miners (Fig. 2).

Working methods suitable to the geological settingTools

In hard rock as marble, progress in the shafts, galleries and stopes was almost exclusively perfor-med using hammer and handpick (Löhneiss, 1617; Waelkens, 1990). In the schist, more friable, miners used pickaxes, mattocks and iron wedges.

Two scenarios emerge according to the depth and position of the ore deposits:

Mineralized outcrops and shallow deposits

They were initially operated from the surface and deeply by winzes and drifts. The miners ex-tracted the ore from the surface from cracks and joints and often starting from karstic hole, more rarely by sinking shafts from the surface (Spi 15 upper network). Some shallow joints were opencast mined.

In order to progress the miners dug sideward horizontally small section galleries, to probe the size of the mineralization. Working galleries were often deepened after an initial stoping. The inclined extraction was done from the main gallery, by digging the floor. It is therefore common to see the different marks of working faces and drifts at the top of large stopes (Mi 7, Spi 15) (Fig. 3). They represent the first step of underhand stoping, initial phase of a generalized lateral robbing.

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Fig. 3: Mining in marble (Spi 15): Inclined extraction from the main gallery, by digging the floor – conceptual schema.

Some of these works present adjacent exploratory drifts which sometimes are intersecting or coalescent and can be real maze. They look like an anastomosed network which develops into three dimensional ways. Subsequently, this initial framework can be enlarged by stoping walls, roof and floor (Mi 7).

In the Spi 15 shaft upper network, which is close to the first contact, a blind shaft cut from bot-tom to top was found; such a structure exists in the lower part of the Spi 5 network to provide an access to a higher level.

Deep mineralizations

Two kinds of access toward deep mineralizations can be distinguished according both to geo-morphology and to the occurrence layer.

- Beneath the plateau, stoping works are linked to the main shafts sunk from Upper Kamariza marble by narrow quadrangular section galleries. Stoping works extend along the axis of a drift through Kamariza schist or in lower Kamariza marble. From there, miners proceeded by cutting

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working faces (Gruner, 1922) or cells more or less equidistant, while continuing exploitation toward the drift. On either side of it, 5 to 15m long stopes were opened. In the Megala-Pefka-Spi 18 underground network, the height of the drifts ranges from 0.80m to 2.80m. The survey carried out accurately reproduces the morphological characteristics of this kind of network connected up, at the third contact (- 80m), by one of the deepest vertical shafts (101.50m).

The waste (ecvolades) lies directly on the floor, the larger blocks were crushed or carrefully stacked in low walls along the pathways to contain smaller fractions.

This working method made the roof more secure by preserving residual pillars. The stopes were backfilled to get a sufficient height to carry on the works; therefore only mineralized rocks were hoisted to the surface.

- On the western slope of the plateau, the bottom of the shafts sunk from Kamariza schist out-crop often opens in the main gallery or in a stope after an eastward offset of axis. Due to the poor stability of the schist, this voluntary offset improved miner’s safety at this connecting level. The average orientation of the main gallery is then parallel to the slope. Stopes are developed mostly towards the plateau (Spi 63 network). The quadrangular section main gallery cut in the rock or embanked in stopes partially walled, goes from one stope to another. Stopes are 30 to 40m of horizontal development and 0,80m to a few m high.

The heterogeneous texture of the schist layers prevents cutting it as accurately and securely than marble. Fracturing is a key factor for working options. Except a few pillars, the lack of sup-port induces the collapse of large slabs from the roof. When mineralization goes deeper, miners opened inclined works by digging from the main gallery. Stoping was realized on both sides of these level galleries. The ore was carried outside on men’s backs or by dragging.

Mining chronology – first resultsMost explored ancient mines seem to fit with a single operating phase. They do not appear to have been a subject to resumption of work except for some networks opened in Lower Kamariza marble (Mi 7) and some others close to surface (Spi 20), easily accessible where the old works can be seen among more recent stopes mostly dated from the nineteenth century. In Megala Pefka – Spi 18 network carried out on the third contact, one can wonder about widenings for-ming real stoping, the succession of several operating phases has to be considered.

Age dating

According to historical and archaeological data (Ardaillon, 1897; Healy, 1978; Hopper, 1968; Kalcyk, 1982; Lohmann, 2005) complemented by the observations of mining engineers (Cordella, 1869; Conophagos; 1980), a full mining activity in the Laurion area is known during the fifth and fourth century BC and a short recovery during the second century BC.

Fragments of oil lamps found during explorations confirm the fourth century BC data, and in-dicate roman and byzantine operational phases too in some networks (Blondé, 1983; Butcher,

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1982). Several radiocarbon ages on charcoal from small fire places confirm these three main periods.

A short mining portion located at the end of the Spi 18 shaft network shows very narrow galleries and working faces typically worked by fire setting. Charcoal remaining from fire setting places provides a first radiocarbon age (fifth to sixth century AD; 2 sigma cal AD 411: cal AD 542; Poz-47265/Spi18-M5) that could date byzantine mining works.

AcknowledgementsThis study was supported by TRACES Laboratory, University and CNRS, Toulouse; Chrono-Environment Laboratory, University of Franche-Comté; University of Lorraine; Lavrion Tech-nological and Cultural Park; Municipality of Lavrio; French School at Athens (EFA); PERSEE Association; Fenzy-Honeywell Safety Products France. We are grateful to the members of the ERMINA National Association whose endurance was severely tried and tested during the under-ground explorations.

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