William S. O'Brien

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William Shoney O'Brien
Born 1825
Abbeyleix, Ireland[1]
Died May 2, 1878 (aged 52–53)
San Rafael, California
Cause of death Bright's disease[2]
Resting place Holy Cross Cemetery, Colma (reinterred from San Francisco's Calvary Cemetery)
Nationality American
Occupation Saloonkeeper, stockbrocker, partner in Comstock Lode mines
Organization Flood & O'Brien
Consolidated Virginia Mining Company
Bank of Nevada
Known for Being one of the "Bonanza Kings"
Net worth USD $12 million at the time of his death (approximately 1/696 of US GNP)[3]

William S. O'Brien (1825 – May 2, 1878) was an American businessman who formed a business partnership with fellow Irishmen James Graham Fair, James C. Flood, and John William Mackay, the Consolidated Virginia Mining Company. The four dealt in mining stocks and operated silver mines on the Comstock Lode, and in 1873 discovered the great orebody known as the "Big Bonanza" in the Consolidated Virginia and California Mine, an orebody more than 1,200 feet deep, which yielded in March of that year as much as $632 per ton, and in 1877 nearly $190,000,000 altogether. The four-way partnership, although formally called "Flood and O'Brien," was more commonly known as the Bonanza firm. Together they also established the Bank of Nevada in San Francisco, California.

He is considered to have been one of the 100 wealthiest Americans, having left an enormous fortune.[3]


  1. ^ Denslow, William R.; Truman, Harry S. (1957), 10,000 Famous Freemasons, III, Trenton, Missouri: Missouri Lodge of Research, p. 280, ISBN 978-1-4179-7579-2, OCLC 11337271, retrieved 2011-07-30 
  2. ^ "THE LATE W. S. O'BRIEN", The New York Times, New York, New York, May 12, 1878 
  3. ^ a b Klepper, Michael; Gunther, Michael (1996), The Wealthy 100: From Benjamin Franklin to Bill Gates—A Ranking of the Richest Americans, Past and Present, Secaucus, New Jersey: Carol Publishing Group, p. xii, ISBN 978-0-8065-1800-8, OCLC 33818143 

External links[edit]

William S. O'Brien at Find a Grave