| About this Abstract |
| Meeting |
MS&T22: Materials Science & Technology
|
| Symposium
|
Art and Cultural Heritage: Discoveries during the Pandemic Year
|
| Presentation Title |
Reproduction of Melting Behavior for Vitrified Hillforts Based on Amphibolite, Granite, and Basalt Lithologies |
| Author(s) |
John McCloy, José Marcial, Jack S. Clarke, Mostafa Ahmadzadeh, John Wolff, Edward Vicenzi, David Bollinger, Erik Ogenhall, Mia Englund, Rolf Sjöblom, Albert A Kruger |
| On-Site Speaker (Planned) |
John McCloy |
| Abstract Scope |
European Bronze and Iron Age vitrified hillforts have been known since the 1700s, but archaeological interpretations are still debated. We carried out experiments to constrain conditions leading to vitrification of wall rocks in the hillfort at Broborg, Sweden. Potential source rocks were collected locally and heat treated in the laboratory, varying maximum temperature, cooling rate, and particle size. Crystalline and amorphous phases were quantified using X-ray diffraction in situ, during heating and cooling, and ex situ, after heating and quenching. Textures, phases, and glass compositions were compared with samples from the vitrified wall and equilibrium crystallization calculations. ‘Dark glass’ formed from amphibolite rocks melted at 1000-1200°C under reducing atmosphere then slow cooled. ‘Clear glass’ formed from non-equilibrium partial melting of feldspar in granitoid rocks. This study aids archaeological forensic investigation of vitrified hillforts and interpretation of source rock material by mapping mineralogical changes and glass production under various heating conditions. |