Analysis of Urnfield Period Bronze Droplets Formed during Casting

Abstract

The Late Bronze Age copper mining site “Gasteil Cu I” (ca 1050–850 BC) is located in the district of Neunkirchen, Lower Austria. Since 2010 five excavation campaigns took place and many artifacts as well as corroded metallic droplets were discovered. Two of these droplets were investigated by metallography. At the droplet ́s surface tin was measured, indicating that these droplets are formed during bronze casting. The small droplet is severely corroded but in its core the original bronze alloy is still present. The analysis showed about 10 wt.% Sn. The microstructure is characterized by a Cu-Sn solid solution and a Cu-Sn intermetallic phase. Additionally small amounts of Cu2S were observed in the metallic core. The corroded rim contains oxides and hydroxides of Cu and Sn and other impurities like Ca, P, Si, S and Fe. Analyzing the corrosion products, Sn concentrations up to 40 wt.% were measured. This enrichment can be explained by a simultaneous formation of insoluble SnO2 and Cu ions, which were transported to the surface. Surprisingly, the other large droplet has a corroded core and metallic phases are remaining at the rim. The microstructures of the corrosion products reflect the original casting microstructures of the bronze.

Dig out, Dig in! Plant-based diet at the Late Bronze Age copper production site of Prigglitz-Gasteil (Lower Austria) and the relevance of processed foodstuffs for the supply of Alpine Bronze Age miners

“…Chances are therefore very high that the identified weeds are not arable weeds but that they rather reflect locally growing ruderal taxa. This gets even more likely as the metallurgical processes documented for Prigglitz-Gasteil such as smelting or alloying [ 40 , 41 ] all require fire—charring will therefore only occur to a minor extent in cooking fires, while most charring events will be connected to technical fires. At the current state of research, we cannot exclude that the charred remains of weeds could be entirely unrelated to in situ cooking processes.…”

“…Numerous finds from the accumulated cultural layers indicate the refinement of copper, casting of bronze objects, bone and antler working as well as cooking and food consumption. The area investigated on terraces 3 and 4 (Fig 3) is therefore interpreted as the habitation of the mining community working there and/or the workshops of people supplying the miners [3,19,[39][40][41].…”

Melting, smelting, and recycling: A regional study around the Late Bronze Age mining site of Prigglitz-Gasteil, Lower Austria

“…The copper alloy and ore samples investigated in this paper were excavated from the Prigglitz-Gasteil site in the district of Neunkirchen, Lower Austria (Fig 1 :Star). The site was discovered in the early 1950s and investigated in 1956 and 1958 by archaeologist Franz Hampl and [16,[37][38][39]. These investigations showed a complete chaîne opératoire for copper metal production, including an opencast ore mine, beneficiation and primary ore smelting infrastructure, evidence for the refining of black copper, and alloying and casting of copper-based objects.…”

Die prähistorische Kupfermetallurgie – allgemeine Betrachtungen

“…Zusätzliche Schwankungen in den Legierungszusammensetzungen entstehen durch die Verwendung der verschieden hergestellten Kupferqualitäten (Abb. 7; [20,21]). Recyclingkupfer wird, wie der Name vermuten lässt, durch Verschmelzen bereits verwendeter Kupferteile erhalten.…”