Bonanza is a Spanish term meaning "rich ore body"; in 1873, after gaining control of the Consolidated Virginia Mining Company, they discovered a large vertical ore body more than 1,200 feet deep which became known as the "big bonanza".
[1] In 1871, Irish-Americans John William Mackay, James Graham Fair, James Clair Flood, and William S. O'Brien, organized the Consolidated Virginia Silver Mine near Virginia City, Nevada, from a number of smaller claims on the Comstock Lode and later added the nearby California mine.
Mackay and Fair had the mining knowledge and Flood and O'Brien raised the money.
In 1873, the "big bonanza" was uncovered and San Francisco and the entire mining world were hurtled into a fever of excitement.
Production began to fall off in 1879 but in twenty-two years of operation the two mines yielded more than $150,000,000 in silver and gold, and paid $78,148,800 in dividends, making the four owners into some of America's wealthiest men.