She was not the typical mining engineer of the 1960s. Wearing pearls and sporting a strawberry blond bouffant hairdo, Peggy Keenan spent one week a month in New York City raising money and making deals. The rest of the time, she was in the Black Hills supervising the work of her company, Northwest Defense Minerals (also known as Northwest Beryllium).
Born in San Francisco, Keenan's interest in rocks and geology began at a young age. Her father developed mining properties and took her on frequent expeditions to the Sierra Nevada mountains when she was a girl. She came to the Black Hills when "it was real, raw frontier."
A professional pianist, Keenan started studying music around the same time she became interested in geology. She attended the University of Southern California where she majored in music. In the mid-1950s, she married Canadian naturalist and author John Stanwell-Fletcher. The pair traveled to India and were slated for the North Pole in 1955, but the scientific expedition they were on to determine the thickness of Artic ice turned back because of supply problems.
Keenan organized her mining syndicate in 1956 with hopes of beginning operations in the Black Hills the following year. At the Holy Terror Mine near Keystone, her employees used flotation methods to extract feldspar, mica, beryl and other minerals. Her company was the first in the world to develop a mechanical process for producing beryl concentrate. At the height of the mine's success, she employed 65 men.