Long before Columbus reached America, Indians extracted native copper in the Lake Superior region and worked it into articles used by tribes throughout the continent. French explorers learned of the vast copper deposits but were unable to mine the metal. In 1771 an English group unsuccessfully tried to mine copper near the Ontonagon Boulder, a huge mass of native copper weighing three tons. In 1841 Douglass Houghton's survey of copper resources was printed, and prospectors by the hundreds soon flocked there. Boom towns sprang up. The Phoenix was the first real mine to begin operation, but the Cliff was the first to show a profit. Soon miners were tapping rich deposits all along the Keweenaw Peninsula's backbone. Until 1887, this was the country's leading center of copper production. It has been virtually the only area in the world with any substantial native copper production. At the White Pine Mine, copper is found in combination with other elements, where a great new mining operation began in the 1950s.