2nd Mining in EuropEAn History-confErEncE The

2 Mining in European History-Conference
The Impact of Historic and Prehistoric Mining Activities on the Environment and Societies in Europe
nd
INNSBRUCK - November, 7th - 10th, 2012
PREHISTORIC MINES OF THE UPPER ESARO VALLEY
(CALABRIA, ITALY)
Anna Garavelli*, Felice Larocca**, Chiara Levato**, Daniela Pinto*
Abstract. Recent researches and explorations carried out in north-western Calabria have revealed the exceptional mining vocation of the Upper Esaro Valley (province of Cosenza). In this area, characterized by mountainous
reliefs reaching 2000 metres above sea level, there are karst cavities with rich outcrops of iron and copper ore within them. The commonest minerals occurring in the caves are those typical of karstic environments: calcite is
certainly the most widespread one. It appears in various forms as massive types, forming the walls of the cavities. Minor amounts of other carbonates such as aragonite, dolomite, malachite and azurite have been also identified,
as well as yukonite, goethite, lepidocrocite, limonite, gypsum, apatite-(CaOH) and sampleite. Iron minerals in form of oxides, limonite, and hydroxides, goethite, attracted human attention already during the Upper Palaeolithic
and particularly during the Neolithic and Copper Age (when the exploitation of Cu-carbonates malachite and azurite began). Natural cavities such as Grotta della Monaca and Grotta del Tesauro, extending on the whole for several
hundred metres, have allowed exceptional preservation of prehistoric mining evidence. The calcareous containers represented by karst caves have perfectly protected the archaeological contents related to old mining exploitations.
A wide range of evidence enables us to understand properly the characteristics of the mining activities carried out in these sites during the prehistoric age, evidence such as tools found in the caves-mines and their marks left on
the mineralized veins; the specific choice of mining areas; the occurrence of structures like dry-stone walls and support pillars and finally, proofs related to underground lighting systems.
PREGROTTA
entrance
SALA DEI PIPISTRELLI
Fig. 4 - The impressive entrance of Grotta della Monaca.
0
30 m
Fig. 5 - Schematic plan of Grotta della Monaca with indication of the main underground sectors.
is a smaller cave, about 60 metres in length, located 500 metres above
sea level. It is composed by an entrance area, called “Antegrotta”, and
an uphill gallery from which depart three dead-end branches (Figs. 6-7).
Both cavities were frequented during Prehistory for the exploitation of iron
hydroxides, such as goethite, and copper carbonates, such as malachite
and azurite. The evidence identified within them has allowed the reconstruction of ancient exploitation techniques. The main mining process
feature is surely the use of natural cavities as profitable means of access
to metalliferous resources, therefore avoiding fully artificial excavations.
The tools used for mining iron hydroxides have not been found but left
several digging traces, preserved thanks to the soft goethite nature due
to its high hydration. These imprints can be found both on veins and on
small goethite boulders scattered on the ground and inside archaeological deposits. It is possible to identify blows left by picks made of deer antler and goat horn, small hoes and scapulas used as shovels (Figs. 8-9).
These implements utilization was allowed by the low hardness degree of
this hydrous goethite variety preferred by prehistoric miners, whilst the
Fig. 6 - Entrance area of Grotta del Tesauro seen from the inside during archaeological excavation.
hardest and most compact one was discarded. Waste materiINNER CAVE
als were piled as dry-stone walls in order to free the narrowest underground passages. Goethite pillars were left in some
mining sectors to support the unstable roof preventing this
way its potential collapse (Fig. 10).
Copper carbonates were extracted by hammerstones with grooves and notches,
both purposive for organic material hafting (Fig. 11). These tools were used for
stripping ground deposits containing
copper ores, as testified by smashed
entrance
stalagmites, stalactites and flowstones
magnetic
found within them. Regarding grooved stone
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ANTEGROTTA
implements as ancient mining activities guide
fossils, their finding in Upper Esaro Valley surroundFig. 7 - Schematic plan of Grotta del Tesauro.
ings, within a range of 20 kilometres - in villages as San Donato
di Ninea, Acquaformosa and Saracena - might suggests the existence of a wider and more composite mining district. For
the underground lighting prehistoric miners used torches made of small resinous wooden branches. Thanks to the analysis of charcoal remains dropped from torches and deposited in sediments it has been possible to identify Pinus sylvestris
as one of the most used species of wood.
According to radiocarbon dating, the
iron mining activities
of Upper Esaro Valley
4 cm
began occasionally al- 0
ready during the Upper
Palaeolithic, about 20,000 Fig. 11 - Grooved stone tool
Grotta della Monaca
years BP, and increased from
used for copper carbonates
by the Final Neolithic, be- mining activities.
tween the end of the V and
the beginning of the IV millennium BC. Alongside
iron hydroxides exploitation, during the Early Copper Age - IV millennium BC - copper ores mining
began. After this period iron exploitation seems to
0
2 cm
0
4 cm
resume in post-Medieval Age, as galleries excavated by metallic implements attest.
Fig. 8 - Digging trace left on soft goethite by Fig. 9 - Small hoe imprints on a highly Fig. 10 - Goethite support pillar spared by
0
a bone or antler tool stroke.
Fig. 3 - Samples of the main minerals from the Upper Esaro Valley prehistoric mines. From top to
bottom, clockwise: goethite earthy variety; malachite and azurite on carbonic rock; small hematite
boulder; malachite smearing on little limestone boulders; yukonite; aragonite concretion.
CUNICOLI TERMINALI
10 m
hydrated goethite vein.
prehistoric miners to prevent roof collapse.
References
Larocca, F. (ed.) (2005): La miniera pre-protostorica di Grotta della Monaca (Sant’Agata di Esaro - Cosenza). Roseto Capo Spulico.
Larocca, F. (2010): Grotta della Monaca: A Prehistoric Copper and Iron Mine in the Calabria Region (Italy). In: Anreiter P. et al. (eds.), Mining in European History and its Impact on Environment and Human
Societies. Proceedings for the 1st Mining in European History, Conference of the SFB-HIMAT (Innsbruck, 12-15 November 2009). Innsbruck, pp. 267-270.
Larocca, F. (2012): Grotta della Monaca (Calabria, Italia meridionale). Una miniera neolitica per l’estrazione dell’ocra. In: Borrell M. et al. (eds.), Xarxes al Neolitic, Actes Congrés Internacional (Gavà/Bellaterra,
2-4 febrer 2011). Rubricatum 5, pp. 249-256.
* Università degli Studi di Bari “Aldo Moro” - Dipartimento di Scienze della Terra e Geoambientali
Centro Interdipartimentale “Laboratorio di Ricerca per la Diagnostica dei Beni Culturali”
** Università degli Studi di Bari “Aldo Moro” - Gruppo di ricerca speleo-archeologica
Centro Regionale di Speleologia “Enzo dei Medici” - Commissione di ricerca per l’Archeologia delle Miniere
Contacts: A. Garavelli [email protected] - F. Larocca [email protected] - C. Levato [email protected] - D. Pinto [email protected]
All photos and drawings in Figs. 5 and 7 by Felice Larocca; geographic map in Fig. 1 by Francesco Breglia; English text edited by Chiara Levato and Maria De Falco. This poster can be downloaded in pdf format through www.grottadellamonaca.it (“Bibliografia scaricabile” web page).
The prehistoric mines of the Upper Esaro Valley are located in the municipality district of
Sant’Agata di Esaro (province of Cosenza),
Calabria, Southern Italy (Figs. 1-2).
This area is characterized by rich outcrops
of iron and copper ore occurring within karst
cavities. The commonest mineral phases in
the caves are calcite with subordinate aragonite and dolomite. These are very common
cave minerals whose presence is connected to
precipitation processes from Ca-rich circulating waters. Among iron oxides and hydroxides,
goethite [αFeO(OH)], its polymorph lepidocrocite [γFeO(OH)] and limonite, a mixture of
hydrated iron oxide-hydroxides in varying composition, are the most abundant phases. Subordinate amounts of hematite [αFe2O3] are
also present. Iron oxides and hydroxides occur
everywhere within investigated mines: on the
walls and on the roofs of the caves, as well as
filling fractures in the rocks or on the ground of
the cavities. Additional mineral phases identi- Fig. 1 - Upper Esaro Valley geographic map. Red points show locations of the main prehistoric mines.
fied in products from the area are the Cu-carbonates malachite [Cu2(CO3)(OH)2] and azurite
[Cu3(CO3)2(OH)2]. Gypsum [CaSO4·2H2O], apatite-(CaOH), Cu-sulphates and phosphates brochantite [Cu4(SO4)(OH)6], libethenite [Cu2(PO4)
(OH)] and sampleite [NaCaCu5(PO4)4Cl·5H2O],
as well as the rare hydrated arsenate yukonite
[Ca2Fe3(AsO4)4(OH)·12H2O] are also present
(Fig. 3). Copper mineralization appears as
green and bluish-green crusts covering the
rock walls. All of these copper phases are secondary minerals, whose occurrence in the Upper Esaro Valley mines derives from primary
deposits of chalcopyrite veins within the rocks
of this area.
Evidence related to ancient mining activities has been recognized inside two natural
cavities, Grotta della Monaca and Grotta del
Tesauro opening on the opposite sides of the Fig. 2 - Upper Esaro Valley.
valley, overlooking each other. They have been
investigated since 1997 by a multidisciplinary Italian research team of the University of Bari in collaboration with Centro Regionale di Speleologia
“Enzo dei Medici”. Grotta della Monaca, on Esaro River hydrographic left, is a large cave system composed of galleries, chambers and narrow passages which extends on the whole for about 400 metres. Its impressive entrance is located at an altitude of 600 metres above sea level (Fig. 4). The
cave can be divided into three main sectors: the “Pregrotta”, a wide entrance gallery; the so-called “Sala dei pipistrelli”, a huge chamber in the middle
of the cave system; the “Cunicoli terminali”, a series of low and narrow final passages (Fig. 5). Grotta del Tesauro, on Esaro River hydrographic right,
magnetic
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