Obsidian Hydration Dating: Summary and Status of a Physics-Based Approach

ABSTRACT

Obsidian hydration dating (OHD) is a method of computing archaeological ages based on measuring water absorption by obsidian artifacts, and is widely used in the western United States. This abstract provides a single resource for the OHD user, including advances over the past decade. We describe obsidian mineralogy as it affects OHD; the effects of structural water content on hydration; the mathematical form of the hydration law; methods to control for structural water content and temperature history; methods for computing hydration rates; an analysis of error sources; and a method for conducting an OHD analysis. We address OHD as currently practiced in the western United States, based on optical microscopy, and do not describe newer, experimental methods such as Secondary Ion Mass Spectrometry or infrared (IR) spectroscopy. An associated OHD workbook in MS Excel is available on the website of the International Association for Obsidian Studies.

RESUMEN

La datación por hidratación de obsidiana (DHO) es un método para calcular las edades arqueológicas basado en la medición de la absorción de agua que se produce en los artefactos de obsidiana. Resumimos nuestra comprensión actual de la mineralogía de la obsidiana y cómo afecta la DHO, los efectos del contenido de agua estructural en la hidratación, la forma matemática de la ley de hidratación, los métodos para controlar el contenido de agua estructural y el historial de temperatura, los enfoques para calcular las tasas de hidratación, un análisis de error para fuentes de obsidiana, y un procedimiento integrado para realizar análisis DHO. Abordamos como se practica DHO actualmente en el oeste de los Estados Unidos y sugerimos formas de mejorarlo. Proveemos un libro de trabajo de DHO en MS Excel que está disponible en el sitio web de la Asociación Internacional de Estudios de Obsidiana.

KEYWORDS:

• Obsidian
• chronometrics
• dating

Acknowledgments

We thank three anonymous reviewers on an earlier draft of this article. Their insightful comments have led us to sharpen the focus and clarify a number of points. Any remaining errors, whether of omission or commission, are ours.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.