 1960 Obsidian hydration dating

Obsidian hydration dating is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.Obsidian hydration dating was introduced in 1960 by Irving Friedman and Robert Smith of the United States Geological Survey.1960 Gas laser

A gas laser is a laser in which an electric current is discharged through a gas to produce light.