Wilbert E. Warnke, 96, a retired Department of Energy metallurgical engineer who worked at the old U.S. Bureau of Mines for more than 30 years, died Oct. 8 at Willows at Meadow Branch, an assisted-living facility in Winchester, Va.

He had dementia, said his daughter, Dr. Christine Warnke.

Mr. Warnke began working as a metallurgical engineer for the Bureau of Mines in Rolla, Mo., in 1940. After a two-year stint at the Department of Veterans Affairs in Ely, Nev., he returned to the Bureau of Mines and moved with the agency to College Park in 1948.

At the Bureau of Mines, he patented a process for producing a lightweight aggregate for concrete in 1975. He was also a site superintendent and oversaw a number of mineral research and conservation projects, his daughter said.

From 1977 until his retirement in 1979, Mr. Warnke was a senior metallurgical engineer at the newly established Office of Fossil Energy at the Energy Department. He was also a consultant to an international economic development organization.

Wilbert Eugene Warnke was born in Custer, S.D., and was a 1940 metallurgical engineering graduate of the South Dakota School of Mines & Technology.

Mr. Warnke was a Washington resident before moving to Chevy Chase in 2003. He relocated to Maine in 2006.

His wife of 54 years, Elizabeth Patterson Warnke, died in 2002.

Survivors include a daughter, Dr. Christine Warnke of Washington; two stepchildren, Angelo Patterson of Washington and Mary Patterson of McLean; one brother; and two grandchildren.

— Megan McDonough