Solfataric alum exploitation during the Greco-Roman period: some considerations on its nature, enrichment and preparation for the market

Photos-Jones, E. and Christidis, G. E. (2022) Solfataric alum exploitation during the Greco-Roman period: some considerations on its nature, enrichment and preparation for the market. In: Hulek, F. and Nomicos, S. (eds.) Archaeology and Economy in the Ancient World: Ancient Mining Landscapes. Panel 4.2. Propylaeum: Heidelberg, pp. 19-33. ISBN 9783969290705 (doi: 10.11588/propylaeum.896)

Abstract

In the Greco-Roman (G-R) period, alum, the traded commodity, was used extensively by many industries (e.g. textiles, tanning, metals, or as mineral medicinals). It is thought to have travelled from source (the volcanic landscapes of Greece and Italy) to markets, in dedicated amphorae. Alum, the raw material, was made up of a combination of alum group and other minerals, both soluble and insoluble. The two components would have been separated via a cycle of dissolution-evaporation prior to packaging and shipment. But in what shape did alum, the commercial product, travel to market? We present here simple laboratory-based experiments, combined with X-Ray diffraction (XRD) analysis, to demonstrate that alum, the shipped product from these sources, would have been a gel-like material of varying colouration, from clear/off-white to darker shades, depending on level of iron impurities. Aluminium sulfates are highly hygroscopic; travelling as a gel rather than powder, over long-distance sea routes, would have ensured that the product arrived at its destination in a market-approved condition. Travelling as powder would have resulted in water absorption and stickiness.

• Item Type: Book Sections
• Additional Information: (Archaeology and Economy in the Ancient World: Proceedings of the 19th International Congress of Classical Archaeology, Cologne/Bonn 2018, Band 25) published under a Creative Commons licence: https://creativecommons.org/licenses/by-sa/4.0/ Attribution ShareAlike 4.0.
• Status: Published
• Glasgow Author(s) Enlighten ID: Photos-Jones, Dr Effie
• Authors: Photos-Jones, E., and Christidis, G. E.
• College/School: College of Arts & Humanities > School of Humanities
• Publisher: Propylaeum
• ISBN: 9783969290705