Obsidian hydration dating

Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.

Obsidian is a volcanic glass that was used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through knapping, or breaking off pieces in a controlled manner, such as pressure flaking.

Obsidian obeys the property of mineral hydration and absorbs water, when exposed to air at a well-defined rate. When an unworked nodule of obsidian is initially fractured, there is typically less than 1% water present. Over time, water slowly diffuses into the artifact forming a narrow "band", "rim", or "rind" that can be seen and measured with many different techniques such as a high-power microscope with 40–80 power magnification, depth profiling with SIMS (secondary ion mass spectrometry), and IR-PAS (infra red photoacoustic spectroscopy).^[1]^[2] In order to use obsidian hydration for absolute dating, the conditions that the sample has been exposed to and its origin must be understood or compared to samples of a known age (e.g. as a result of radiocarbon dating of associated materials).^[3]^[4]

^ Stevenson, C.; Liritzis, I.; Diakostamatiou, M. (2002). "Investigations towards the hydration dating of Αegean obsidian". Mediterranean Archaeology & Archaeometry. 2 (1): 93–109.
^ Stevenson, C.; Novak, S. W. (July 2011). "Obsidian hydration dating by infrared spectroscopy: method and calibration". Journal of Archaeological Science. 38 (7): 1716–26. Bibcode:2011JArSc..38.1716S. doi:10.1016/j.jas.2011.03.003.
^ Meighan, Clement (1976). "Empirical Determination of Obsidian Hydration Rates from Archaeological Evidence". In R. E. Taylor (ed.). Advances in Obsidian Glass Studies. pp. 106–19. ISBN 978-0-8155-5050-1.
^ Liritzis, Ioannis & Stevenson, Christopher M. (2012). Obsidian and Ancient Manufactured Glasses. Albuquerque: University of New Mexico Press.

[Investigations_towards-1] Stevenson, C.; Liritzis, I.; Diakostamatiou, M. (2002). "Investigations towards the hydration dating of Αegean obsidian". Mediterranean Archaeology & Archaeometry. 2 (1): 93–109.

[Obsidian_hydration_dating_by_infrared-2] Stevenson, C.; Novak, S. W. (July 2011). "Obsidian hydration dating by infrared spectroscopy: method and calibration". Journal of Archaeological Science. 38 (7): 1716–26. Bibcode:2011JArSc..38.1716S. doi:10.1016/j.jas.2011.03.003.

[3] Meighan, Clement (1976). "Empirical Determination of Obsidian Hydration Rates from Archaeological Evidence". In R. E. Taylor (ed.). Advances in Obsidian Glass Studies. pp. 106–19. ISBN 978-0-8155-5050-1.

[4] Liritzis, Ioannis & Stevenson, Christopher M. (2012). Obsidian and Ancient Manufactured Glasses. Albuquerque: University of New Mexico Press.

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