FAIRBANKS—All good scientific explorations begin with a mystery, and the one that has Jeff Rasic in its grasp started with a mysterious shard of obsidian he picked up in Yukon-Charley Rivers National Preserve. 

Obsidian is volcanic glass with a specific chemical fingerprint that allows archaeologists to pinpoint its origin from anywhere around the planet. The nearest source to Yukon-Charley is hundreds of miles away. So where did it come from and how did it get there? Rasic, chief of resources for Yukon-Charley and Gates of the Arctic National Park and Preserve, will talk about his efforts to answer those questions on Wednesday, July 29, as part of the University of Alaska Fairbanks Summer Sessions’ Discover Alaska lecture series. The free lecture is at 7 p.m. in the Murie Auditorium on UAF campus.

In the past five years, Rasic has used X-ray fluorescence to “fingerprint” more than 10,000 obsidian artifacts in museum collections in Alaska and around the world. The results create a map that allows archaeologists to draw a picture of how Alaskans lived, interacted with each other, and obtained the raw materials they needed to make tools to survive thousands of years ago. 

“It all boils down to movement,” he said. “We can see movement and connection to the past in the obsidian.”

Before metal, people used stone to make tools with cutting edges such as arrows, knives, even prehistoric surgical tools, he said. 

“Obsidian is the finest kind of rock for these things,” he said. “They had to have been particularly valued in Alaska.”

Most obsidian comes from areas in the Aleutians and western Alaska, but archaeologists have found obsidian tools all over the state.

“It was traded or transported widely,” Rasic said. “You can find Alaska obsidian to the Yukon Territory to every corner of Alaska.”

But Alaska obsidian has not been found in the Russian Far East, which puzzles Rasic. 

“We made a very specific attempt to find Alaskan obsidian on the western side of the Bering Strait and were surprised not to find any,” he said.

And despite having a database of 10,000 obsidian artifacts, Rasic is still unable to match the shard he found in Yukon-Charley to any source.

“That’s kind of an interesting message,” he said. “People in the past were really ace geologists who know all these sources and where to find them and exploit them. We still haven’t found all the sources they knew about and we’re having to relearn what they knew.

Contact staff writer Julie Stricker at 459-7532.