There are 2 "John Harvey"s in California in 1900
1900  California, El Dorado, Georgetown
Oldfield, Ron, Head
Harvey, John, pardner, white, male, b. Aug 1865, 34, single, b. Eng
                      Eng, Eng, immig 1884, 16 yrs in US, NA, miner 
                      (gold), out of work 7 months, can read, write, spk
                      Eng
Camp, Albert, pardner
1900 California,  San Francisco,  Naval Training Station
Harvey, John A, private, residence: Chicago, Illinois, male, white,
                     b. Feb 1877, 23, single, b. Eng, Eng, Eng, immig 1877
                     23 yrs in US, NA, can read, write, spk Eng
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1910   Nevada,  Nye,  Manhattan
Harvey, John, head, male, white, 39, single, b. Eng, Ire, Ire, immig
                    1904, NA, spks Eng, miner, gold miner, worker, can
                    read, write, owns home free
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1920   California   Nevada    Grass Valley
Harvey, John, boarder, male, white, 50, marr, immig 1898, alien, 
                      can read, write, b. Eng, Eng, Eng, spks Eng, miner,
                      worker