In 1957, when geologist Ernie Lehmann was sent by a national company to explore Minnesota for copper, he began a lifelong pursuit that led him to be dubbed the "grandfather" of copper-nickel mineral development in northeastern Minnesota.

Lehmann, a prospector for 63 years, led the discovery of one of the world's largest deposits in the Duluth Complex, as well as significant deposits, including more than 1 million ounces of gold, in Montana and Argentina.

A gentle giant in his industry, he helped shape the nation's mining laws by testifying on Capitol Hill. And in Minnesota, three governors appointed him to various mining and strategic metals advisory boards. Adamant that he'd never retire, Leh­mann was involved in a half-dozen businesses when he died at his Minneapolis home on Dec. 13. He was 84.

"Ernie was extremely well known in his geology profession, not just here in Minnesota but nationally and internationally," said Frank Ongaro, executive director of MiningMinnesota, an industry group. "He's literally been doing prospecting and exploration work for half a century, all over the world."

Lehmann was born in Heidelberg, Germany, in 1929, the youngest son of archaeologist Karl Lehmann and Elwine Hartleben. In 1935, he emigrated with his parents and two brothers.

He graduated from Williams College in Massachusetts in 1951 with top honors and did graduate work in geology at Brown University in 1951-52.

While in college, he worked as a miner and geologist at a gold mine in Bannack, Mont., and in 1951, joined Kennecott Copper.

In 1953, he married Sally Willius of St. Paul. In 1957, Kennecott assigned Leh­mann to explore for copper in northern Minnesota, so the couple moved to Minneapolis. They had four children.

In 1958, when he was 29, Lehmann left Kennecott to launch a series of businesses. He worked tirelessly to develop nonferrous mining in Minnesota, while becoming active in political and civic affairs, his family and Ongaro said.

"He goes back to the early days of exploration in and around the Duluth Complex, and had just tremendous historical knowledge of the mineralization from past exploration activities and drill holes that were done decades ago, and the topography, and the ownership of the surface and the ownership of the minerals," Ongaro said.

"Ernie was a walking encyclopedia of all things exploration and mineral development in Minnesota."

He helped found MiningMinnesota and was active in the Society for Mining, Metallurgy and Exploration and the American Institute of Professional Geologists and other groups, winning industry awards.

He worked throughout much of the world for mining companies, trading companies, investors and land owners, said daughter Kate Lehmann. His business and exploration ventures focused on managing and executing mineral exploration, evaluation and development.

Lehmann was president and CEO of Beaver Bay Inc., which owns an interest in the Twin Metals Minnesota copper-nickel project in the Duluth Complex. He was chair emeritus of Vermillion Gold, an early-stage gold exploration company. He also was president of North Central Mineral Ventures Inc.

"Exploration was the theme of his life," Kate Lehmann said.

In addition to Sally and Kate, survivors include brother Wolfgang Lehmann; children Fred, Charlotte and Walter, and two grandchildren.

Services will be at 2 p.m. Jan. 10 at Plymouth Congregational Church, 1900 Nicollet Av., Minneapolis.