Obsidian hydration dating limitations
Humans often used obsidian as a raw material when making chipped stone tools.
The hydration process continues until the fresh obsidian surface contains about 3.5 percent water. The thickness of the hydration rind can be identified in petrographic thin sections cut normal to the surface and observed under a microscope.
► New approach for measuring hydration layer with Secondary Ion Mass Spectrometry.
Obsidian is a volcanic glass that was sometimes used as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through the process of flintknapping.
As any other glass, it is not a crystal, and thus it lacks the lattice structure typical of crystals at the atomic level.
However, glasses do possess some degree of spatial order.
A distinct diffusion front can be recognized by an abrupt change in refractive index at the inner edge of the hydration rind.