Treasure in Ancient Trash: Learning About Japan’s History Through Metals Waste

Written by
Kevin McElwee for the Office of the Dean for Research
Jan. 2, 2019

Thomas Conlan fiddled with a strange, brownish-black rock on his desk. For centuries, people had considered the piece of rubble worthless, but it is priceless to Conlan’s research.

The lumpy rock is a sample of slag, the material left over after heating ore to extract valuable metals. With researchers from art, engineering and materials science, Conlan is exploring whether these discarded scraps can fill gaps in early Japanese history.

Conlan, a professor of East Asian studies and history, hopes to use the mining waste to learn about the political and cultural climate of Japan in the eighth to 18th century CE, a period for which written records are sparse.

Much of Conlan’s slag comes from the smelting of copper, a metal that played an important role in historical trade, monuments and coinage. “We know there was an incredibly vibrant process of metallurgy in the past,” Conlan said. “They were mining tons of this stuff, but there’s nothing really written about it.”

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Princeton researchers Rachel Selinsky, left, and Professor Thomas Conlan, right, are using modern materials analyses to learn about medieval metallurgical practices in Japan. Photo by Denise Applewhite, Office of Communications.