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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 ...
Obsidian hydration dating is a method that allows for the absolute or relative dating of an obsidian sample. The degree of hydration (i.e., water absorbed into the material) observed indicates how long it has been since the obsidian surface was exposed (i.e., through flaking). Obsidian hydration dating is at times, however, unreliable.
The rate at which the obsidian hydration band forms increases with temperature. Second, the rate of hydration and obsidian hydration band formation varies with the geochemistry of the obsidian, including the intrinsic water content, seems to affect the rate of hydration. Finally, water vapor pressure may also affect the rate of obsidian hydration.
Expanded perlite. Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian.It occurs naturally and has the unusual property of greatly expanding when heated sufficiently.
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The source of obsidian for cultures inhabiting the territory of and around Greece was the island of Milos; the Starčevo–Körös–Criș culture obtained obsidian from sources in Hungary and Slovakia, while the Cardium-Impresso cultural complex acquired obsidian from the island outcrops of the central Mediterranean.
The Saqiyah, c. 1905 'Punjab Wheel', India c.1917. A sāqiyah or saqiya (Arabic: ساقية), also spelled sakia or saqia) is a mechanical water lifting device.It is also called a Persian wheel, tablia, rehat, and in Latin tympanum. [1]
The pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca 2+ or calcium hydroxide (Ca(OH) 2) in the presence of water.