The Kesler Mining Company was a silver-mining venture at Big Cottonwood, Utah, about twenty-three miles from Salt Lake. This firm was organized in June 1879 after New York investors purchased a bankrupt mine and claim. It was one of Belknap's early ventures and not particularly successful. The papers cover the organization of the firm from 1878 to 1881, with scattered materials down to 1895. Of particular interest are a series of detailed reports and statements sent by Ellsworth Daggett, the company's agent and superintendent. They describe the difficulties in operating a small western metal mine under absentee ownership.

Other correspondence is between Belknap and the firm's Utah bankers and with members of the New York law firm of De Forest & Weeks, who were associated with Belknap as stockholders and officers. There are maps and sections showing the mine workings, payrolls giving names, occupations and wages of people employed at the mine, legal papers concerning disputes over claims, and a geologist's report.