What obsidian is
Obsidian forms when lava rich in silica cools so fast that crystals have no time to grow. The result is natural glass. Struck carefully, it breaks in smooth, shell-shaped curves and leaves edges thinner than a razor. For tens of thousands of years it was the best cutting tool people in the western Pacific could get.
Twenty thousand years of trade
Obsidian from Mopir, in West New Britain, has been found in rock shelters on New Ireland dated to around 20,000 years ago, when the sea stood far lower than today. Even then the islands were not joined: the stone had to cross open water, by canoe. It is some of the earliest evidence anywhere of people deliberately moving a raw material across the sea.
A fingerprint in stone
Every obsidian source has its own chemical recipe. By measuring a flake's trace elements, archaeologists can tell which volcano it came from, like reading a fingerprint. Using this method, pieces from the Talasea sources have been traced across thousands of kilometres, reaching as far as Borneo in the west and Fiji in the east in the time of the Lapita voyagers.
Visiting the sources
Around Talasea the glass still lies in gardens and on paths near the old quarries. The land belongs to local clans, so ask before you walk, and leave every flake where it is: out of place, it loses the story it can tell.
Questions and answers
What is Talasea obsidian?
It is natural volcanic glass from the Willaumez Peninsula around Talasea, in West New Britain. It breaks into very sharp edges and was prized for tools.
How old is the obsidian trade?
Obsidian from Mopir in West New Britain reached New Ireland around 20,000 years ago, carried by canoe across open water.
How far did Talasea obsidian travel?
In Lapita times, obsidian from these sources reached as far as Borneo in the west and Fiji in the east.