Abstract Drawings, 1871-1970, of the Calumet and Hecla Mining Companies. Contains hand sketches, tracings, blueprints and related manuscript items as well as a card index created by the company. Includes more than 80,000 engineering and architectural drawings gathered by the Calumet and Hecla Mining Company during its active life as a copper mining company in Michigan’s Keweenaw Peninsula. Much of the machinery was built in-house at Calumet and Hecla and they also had need of maps of both aboveground...