The Oreano Mining Company was incorporated in the state of Idaho on November 10, 1902; its capitalization was 1,000,000 shares, par value $1.00. The property, which consisted of five claims known as the Oreano group included the Oreano, Sinker, Pearl, Moonlight Fraction, and Pearl Fraction lodes, was located in the Lelande Mining District near Burke. The lode claims were patented in 1904.

At the first directors meeting, held November 15, 1902, Carl Amonson was elected president. O.E. Anderson, Peter Johnson, Matt Baumgartner, Charles Andres, M.H. Hare, and Charles E. Smith were the other directors. As the first order of business the new company purchased all of the property belonging to the Pearl Mining Company, a South Dakota Corporation, for 700,000 shares of Oreano stock.

In 1904 the company's directors changed. Among the new directors was John Wourms, with Herman Rossi joining the board in 1905. Rossi served as president of the company for many years, resigning from the board in 1916. Charles Smith, a member of the original board, was authorized, in 1903, to sell the company's stock on the east coast. In 1905 a letter from New Hampshire stockholders complained that the mine had been misrepresented and that they had paid too much for their stock. The stockholders went on to say they had confidence in this new board and its officers to improve the management of the mine. At this vote of confidence, the board agreed to a stock reimbursement for all purchases in excess of 20 cents per share.

Early directors meetings were concerned primarily with raising money to pay bills and purchase equipment. In 1904 Oreano entered into a contract with the adjoining Anchor Mining Company for use of Anchor's compressor plant. In order to raise money for the development of the mine frequent stock assessments were levied, the first of these in December 1905. The company reported disappointment in not reaching the ore body, but felt the new tunnel being dug in the fall of 1912 would prove successful. In 1916 the directors decided to sell 100,000 shares of treasury stock in lieu of authorizing yet another assessment.

In 1915 the Sherman Development Company to the north leased the tunnel on the Oreano claim in order to drill into their own workings.

In July 1918 Oreano levied one final assessment before closing the mine for the duration of the war. No more directors meetings were held until July 1922 when assessment #27 was levied to fund the rebuilding of the blacksmith shop and cabin which were destroyed in a snowslide during the winter of 1911-1912. After mining expert Fred Searles inspected the property, assessment #28 was levied in September 1922 and work on a 300' crosscut in the No. 2 tunnel was begun under contract. To facilitate this drilling a compressor and complete mining equipment were installed.

On May 20, 1923, the ore vein was encountered 280 feet from the initial crosscut. There was little ore but the quality was good. An assessment was levied in June to allow the work to continue. When the board of directors met on October 11 to approve payment of bills, there was no hint of a change in leadership. But, at the October 13th stockholders meeting, the first called since 1916, several new stockholders, namely Jerome, Harry, and Henry Lawrence Day, were present. A new board consisting of A.P. Ramstedt, Ramsay Walker, Henry Lawrence Day, P.J. Maggy, Jerome Day, F.M. Rothrock, and John Dolan, the only hold-over from the previous board, was elected. At this meeting a committee was formed to rewrite the by-laws of the company since the old ones contained items contrary to Idaho law, and included items that did not belong in by-laws. At the directors meeting Jerome Day, who was also president of Sherman Lead Company, was elected president. Dolan reported that while he had been with the Oreano only eighteen months and knew little about the company prior to that time, he found the records had been poorly kept. The directors decided to suspend work on the property until an audit could be made of the records.

In 1927 Sherman Lead again asked for an easement to work their property through the Oreano No. 2 tunnel. As part of the agreement Sherman relinquished their claim to the ore in the Oreano tunnel which Sherman claimed as its property due to its claim of the apex of the vein from which the ore was extracted. Since neither company could market this ore without precipitating apex litigation, Sherman Lead, in July 1928, offered to buy Oreano for 175,000 shares of Sherman stock. After a lengthy discussion the board accepted the offer and called a special meeting of stockholders. On August 23, 1928, the stockholders approved the sale and, on September 20, a final assessment was levied to pay the indebtedness of the company. The directors then decided on a pro-rata distribution of the Sherman stock at the ratio of one Sherman Lead share for each five Oreano shares held.