See also The Mackay Family Tree
The Irish-born John W. Mackay I (1831-1902) sailed to California from New York in 1851 hoping to find his fortune in the mines of California during the famous  gold rush. He was having very little success in California when he heard about the discovery of riches in the hills around Virginia City. So, in 1860, he packed his few belongings and moved to Nevada. He started in Virginia City as a miner, but he soon worked his way up to superintendent and became a partner in the Kentucky Mine. Then in 1869, he formed a partnership with James G. Fair, James C. Flood, and William S. O'Brien that became known as the Bonanza Firm, and these silver barons developed the famous Comstock Lode.
In 1873, after 22 years of toiling in many different mines in two states, Mackay struck one of the greatest silver veins in history. His "mountain of silver", the Big Bonanza, as the mine was called, produced more than $400 million in ore in just a little over four years.
For the first few years after the discovery, the mine produced a monthly output of $500,000, most of which went to Mackay. In 1876-77, the mine had its most prosperous years, producing more than $75 million worth of silver, although some estimates go as high as $190 million.
But by the end of 1877, the Big Bonanza was depleted of silver ore. Mackay, along with his partners, who were all millionaires by then, moved to San Francisco. Mrs. Mackay moved first to San Francisco, then to Paris, and finally to London, before coming back to the United States in 1920. She entertained lavishly, wining and dining royalty and heads of state, using the silver service which was the envy of society on both continents.