Obsidian density, connate water and hydration dating

Part of : Mediterranean archaeology & archaeometry : international journal ; Vol.4, No.2, 2004, pages 5-16

Section Title:
The search by many authors for the chemical components most influential in determininghydration rates, for obsidian dating purposes, has had mixed results. Recently it has beendemonstrated that hydration dating is more reliable when individual artifacts are assayed for theircompositional or connate water content, rather than relying on a single source specific chemicalcompositional determination which may overlook the formational water variations betweendifferent parts of an obsidian flow Water measurement may be difficult to achieve for everydateable artifact using the currently preferred system of infrared spectroscopy; small sample sizeand lack of transparency can significantly reduce the quality of the measurement. The relationshipbetween obsidian connate water and density is presented to show that simple density measurementcan in many cases be an alternative to infrared spectroscopy. Results from the analysis of 31obsidians ranging from North America to the southwest Pacific show that useful estimations ofobsidian connate water can be achieved by density measurement. An important finding is themarked difference between the potential hydration rates of 'dry' higher density obsidians of thesouthwest Pacific compared with 'wet' lower density specimens from North America.
Subject (LC):
Obsidian, Hydration, Dating, Connate water, Infrared spectroscopy