In a recent study in the Journal of Archaeological Science, Jonathon Ericson, professor and chair of UCI's Environmental Health, Science and Policy Department, and colleagues introduce a new mineral dating technique called quartz hydration dating. The technique dates artifacts containing quartz, a common mineral found in almost every type of rock.
Quartz hydration dating is based on a natural phenomenon that occurs when a piece of quartz is fractured. When a statue or a common chopping tool or hand ax is made, the surface is chipped, flaked, fractured or polished. Over time, water diffuses into the freshly exposed surface forming a hydration layer. The thickness of this layer can then be measured by a nitrogen particle beam to determine how many years ago the object was made or fractured naturally.
According to Ericson, quartz hydration can date objects that are between 100 and 1 million years old to within 20 to 35 percent of the object's age. Quartz can be found at archaeological excavation sites worldwide from Africa's Olduvai Gorge to China's Choukoutien and even California's Mohave Desert. A ubiquitous mineral, quartz was used in toolmaking from the beginning of human history and also can be found in statues, bowls and ceramics.
The new method, however, is particularly useful for dating quartz-containing artifacts in the "chronological gap" that exists for objects that are between 50,000 to 100,000 years old. Other dating methods are poor performers for this period or have questionable accuracy, and the most familiar dating methods are not effective at all. Radiocarbon dating is good for dating organic material up to around 50,000 years old, and potassium argon dating is good for
Contact: Lori Brandt
University of California - Irvine