Sourcing exotic obsidian from museum collections
JUNE 2011 - What is this Doing Here? Humans have long had a thing for obsidian. The volcanic glass was fashioned into tools by prehistoric cultures and used as knives, scrapers, and projectile points. The edges are exceptionally sharp, sometimes finer than a modern surgical scalpel. It probably helped that obsidian can be quite beautiful, too. "Glassy and smooth, sometimes transparent, often a deep black and other times a vibrant orange or red marked with spots and whirling patterns," said archaeology curator Jeff Rasic.
When it comes to the chemical soup that is obsidian, dozens of trace elements make up the seasonings and almost no two batches are alike. Archaeologists can examine obsidian artifacts with a Star Trek-looking portable X-ray fluorescence analyzer to measure nine strange-sounding elements like niobium, yttrium and rubidum. The meat, vegetables and stock in the recipe.
This "fingerprint" makes it easy to source, as long as you have the data to match it to. When a match is made, the origin of the artifact is established. Often the obsidian tool had been carried hundreds of miles from its source.
Rasic recently examined obsidian artifacts curated at the Alutiiq Museum and Archaeological Repository in Kodiak. Almost all of the obsidian originated from the Okmok Volcano, 675 miles away in the Aleutian chain. The most surprising discovery was an obsidian projectile point from a source known as Batza Tena in Northwestern Alska found on the northwest coast of Kodiak Island. The archaeology collection at the UA Museum of the North includes at least 10,000 Alaskan obsidian artifacts, the largest collection in the world.
Of the 65 or so known obsidian fingerprints in the region including Alaska, the Yukon and British Columbia, 12 can be traced to known sources. Six of those have been pinpointed in the last year by Rasic's team. He hopes to double that number again soon.