John Mackay was born in Dublin, Ireland in 1831. His surname was Scottish, but he identified with his Irish heritage. In 1840, Mackay's family immigrated to New York, his father dying shortly afterwards. John Mackay left school and eventually apprenticed as a shipwright. In 1851, he traveled to California where he gained experience mining for gold.
Mackay came to the Comstock after the 1859 strike seeking employment as a miner. Hard work, sound judgment, and honesty won him respect and eventually the position of the Caledonia Tunnel and Mining Company's superintendent. In 1863, Mackay became a trustee for the newly formed Bullion Mine. Frugal and shrewd, Mackay invested in the corporation. He sold his stocks when they reached an unreasonable height, realizing substantial gain even though the mine proved unprofitable.
In 1866, Mackay and a partner obtained the undervalued Kentuck, a Gold Hill mine. Without offering stocks, they developed the property through crude, inexpensive means. Such limited freelance projects known as rathole mines rarely produced profit, but the Kentuck proved the exception, yielding $3,641,062 in three years.
In 1867, Mackay married the widow Marie Louise Bryant with whom he would have two sons. During that year, Mackay met fellow Irishman James Fair, then superintendent of the Hale and Norcross Mine. When Fair lost that position, Mackay offered him employment as superintendent of the Rising Star Mine, a property he purchased in Idaho. Fair accepted, but the mine failed, freeing the two to pursue other undertakings.
Maneuvering around William Sharon and his Bank of California, Mackay and Fair worked with investors James Flood and William O'Brien to seize control of the Hale and Norcross, turning it to profit. The four men continued obtaining claims. In 1873, while exploring the Consolidated Virginia and California Mine, they discovered an astoundingly rich ore body thereafter known as the Big Bonanza.
With phenomenal profits, Mackay, who owned two-fifths of the partnership, pursued a variety of investments. He and his associates formed the Bank of Nevada to rival Sharon's institution. In the 1880s, Mackay organized two telegraph and postal companies, funding the first telegraph cable across the Atlantic. Mackay had, in fact, founded the first international communication corporation.
For many, Mackay demonstrated that wealth need not ruin character. Even though he acquired more money than anyone else with Comstock investments, he remained unassuming. His gifts to charity including Catholic institutions and to people in need were legendary. Workers praised his daily visits underground dressed as a common miner.
John Mackay left the Comstock for the last time in 1895 and died in London in 1902. Estimates gauged his assets as high as $100 million, making him one the world's richest people. His son Clarence was left to construct the already-designed Pacific telegraph cable. John Mackay is memorialized by the Mackay School of Mines building on the University of Nevada, Reno campus. A 1908 statue of Mackay by Gutzon Borglum, before he went on to sculpt Mt. Rushmore, stands in front of the building, capturing the unpretentious miner with pick axe and sleeves rolled up, ready for work.