File consists of records relating to the Coniaurum mines near Porcupine, Ontario, and the El Canada Colombia Mines Company, which employed Robert Hoffman as a consulting engineer in 1952. File includes correspondence regarding the development of the Coniaurum and El Canada mines; a map of the El Canada mines in Túquerres, Nariño, Colombia; seven vertical cross-sectional drawings of the Coniaurum mines; meeting minutes of El Canada Colombia Mines Company, December 1952; the "Austin Report" on El Canada Mines, written by J.W. Austin in 1929, likely collected by Hoffman after 1934; and a metallurgical report on the gold-bearing ores at El Canada mines, written by E.J. Maust in 1934.

File consists of financial data, gold production, and stockholder lists of El Canada Colombia Mines Company, 1952; correspondence between George F. Brownell and Robert Hoffman regarding the Brownell Exploration, 1925-1926; 2 maps of Giant Yellowknife Gold Mines, near Yellowknife Bay in the Northwest Territories; a list of securities held in safekeeping for Gold Operators (Canada) Ltd., by the Imperial Bank of Canada, 1940; and a balance sheet detailing the assets of the Towne Securities Corp, 1952.