New technology can identify source of ancient stone tools quickly

SHEFFIELD, England, Sept. 11 (UPI) -- Stone tools made of obsidian found at archaeological digs can be traced to their geological source in seconds with a new instrument, British researchers say.

Obsidian, naturally occurring volcanic glass, is hard and sharp when fractured, making it a highly desirable raw material for crafting stone tools for almost all of human history, they said.

Some obsidian tools found in East Africa are nearly 2 million years old, they said.

The chemistry of obsidian varies from volcano to volcano and represents a "fingerprint" allowing researchers to match an obsidian artifact to the volcanic origin of its raw material, but such tests previously required sophisticated equipment in laboratories and often had to wait for months or even years after an archaeological site had been excavated.

Researchers at the University of Sheffield report they've created a hand-held instrument using an analytical technique called portable X-ray fluorescence that enables archaeologists to identify the origins of stone tools in the field rather than having to send them off to a distant lab.

"Obsidian sourcing has, for the last 50 years, involved chemical analysis in a distant laboratory, often taking 5 minutes per artifact, completely separate from the process of archaeological excavation," Sheffield archaeologist Ellery Frahm said.

"We can now analyze an obsidian artifact in the field, and just 10 seconds later, we have an answer for its origin," he said.