Harry T. Mercer was born in Ontonagon, Michigan in 1886, the son of the Hon. and Mrs. James Mercer, pioneer residents of Ontonagon County. He graduated from the town's high school and soon after entered the Michigan College of Mines (later Michigan Technological University), graduating in 1898. Following his graduation, he taught for two years at the college and was the representative mineralogist for the institution at the Paris Exposition 1900 and the Pan-American Exposition, also in 1900 in Buffalo, New York. He was employed on various Copper Country mining properties, including the Centennial, Trimountain and Allouez mines. Prior to being named chief mining engineer of the Copper Range mines, he was specifically mining engineer at the Champion mine. He retired from active mining work with the Copper Range Mining Company in 1951. Mercer was elected treasurer of the Michigan Tech Alumni Association in 1911 and held the position for the next 41 years. Mercer was also an author, publishing a historical sketch of the Copper Range Mining Company, "Fifty years on the South Range" in 1945. Mercer passed away in 1957 after an extended illness.