The firm of Rogers & Brown, Assayers, located at No. 512 California Street, one door west of Montgomery Street, San Francisco, California, was the successor to the firm operated by G.W. Bell (who was killed in an explosion in 1866) and operated from the same location.

An advertisement in the Pacific Coast Directory for 1867 noted: "Gold and Silver Ores Worked. We would inform Photographers that we are prepared to work their Chloride of Silver and Ashes from their Paper Clippings. We have in connection with our Assay Business, a Mill, and are prepared to work gold and silver ores in quantities from 25 to 500 pounds; also Assayer's Sweeps."