| 1868 |
The first air drills were introduced. However, widespread use of air drills in mining did not come for another 30 years. |
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| 1876 |
The stampede to the Bodie district in Mono County began. This rush lasted until about 1888. |
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| 1880 |
Hydraulic mining reached its peak in the state. Vast systems of reservoirs, tunnels, ditches, flumes, and pipelines supplied water to these operations. |
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| 1884 |
Sawyer Decision. In the case of Woodruff vs. North Bloomfield Gravel Mining Company, Judge Lorenzo Sawyer issued a decree prohibiting the dumping of debris into the Sacramento and San Joaquin Rivers and their tributaries. Action against other hydraulic mines soon followed. A few mines constructed tailings storage dams and continued to operate, but hydraulic mining has not been important in the Sierra Nevada since. For a few years, drift mines partially made up for the loss in output of surface placer gold. |
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| 1890 |
Beginning about this time and continuing for several decades, great improvements were made in mining and milling methods. These changes enabled many more lode deposits, especially large but low-grade accumulations, to be profitably worked. The improvement of air drills, explosives, and pumps, and the introduction of electric power lowered mining costs greatly. The introduction of rock crushers, increase in size of stamp mills, and new concentrating devices, such as vanner, lowered milling costs. Cyanidation was introduced in 1896 and soon replaced the chlorination processes. |
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| 1893 |
The Caminetti Act was passed creating the California Debris Commission. This commission licenses hydraulic mining operations in the Sierra Nevada. it is empowered to assess such mines to build debris dams. |
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| 1893 |
Gold was discovered in the Goler Gulch in the El Paso Mountains in eastern Kern County. This led to other discoveries in the area and the influx to the Rand district, which began in 1895. |
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| 1898 |
The first successful bucket-line dredge was started on the lower Feather River near Oroville. Gold dredging soon became a major industry that continued for more than 65 years. |
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| 1904 |
The lost, high-grade Tightner vein was rediscovered at Alleghany in Sierra County. Large amounts of rich ore were taken from this vein, and mining activity, reviving in this district, continued until 1965. This was the last district in the state where gold mining was the chief industry. |
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| 1916 |
The general prosperity that began during World War I and continued until 1929, with accompanying high costs, caused a decrease in gold output. |
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| 1922 |
Argonaut Mine Disaster. A fire on the 3,350-foot level at the Argonaut mine in the Jackson district, Amador County, caused the loss of 47 lives. |
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| 1929 |
Peak of post World War boom. Lowest point in gold production since 1849. |
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| 1930 |
Gold production started to rise because of the depression and resulting low operating costs. |
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| 1933-35 |
The price of gold increased from $20.67 to $35 per fine ounce. This rise ultimately resulted in a large increase in gold output and in much greater exploration activities. |
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| 1940 |
Gold output totaled nearly $51 million. This as the most valuable annual output since 1856. Thousands of miners were employed in the quartz mines at grass Valley, Alleghany, Nevada City, Jackson, Sutter Creak, Jamestown, Mojave, and French Gulch. There were many active bucket-line dredges and dragline dredges became important producers of placer gold. |
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| 1942 |
World War II caused a precipitous drop in gold output. War Production Board Limitation Order L-208, issued on October 8, caused the old mines to be shut down. |
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| 1944 |
Gold production touched the lowest point since 1848. |
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| 1945 |
Order L-208 was lifted, effective July 1. Some of the bucket-line dredges resumed operation, but only a few important lode mines at Grass Valley, Alleghany, and Sutter Creek were reopened. Production increased slightly for 4 years. |
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| 1950 |
Gold output resumed it s decline because of rising costs and depletion of dredging ground. This trend was accelerated by the Korean War. |
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| 1953 |
The Central Eureka Mine at Sutter Creek, the last major operating lode mine in the Mother Lode belt, was shut down. |
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| 1956 |
The mines of the Empire-Star Mines Ltd., and Idaho-Maryland Mines, Inc., at Grass Valley were shut down. The industry of gold mining completed nearly 106 years of operation in the locality. |
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| 1960 |
Gold output fell below $5 million as the dredges continued to curtail operations. |
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| 1962 |
The last dredge of the Folsom field in Sacramento County was shut down, ending more than 60 years of operation. One of the last active lode-gold mines in California, the Sixteen-to-One in Alleghany district, curtailed operations. |
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| 1963 |
The three large dredges of the Yuba Mining Division, Yuba Consolidated Industries--in the Hammonton district, Yuba County—were the only major sources of gold in the state. The small output from the substantial number of part-time prospectors, pocket miners, snipers, and skin divers did not offset the decrease in output from larger commercial operations. Several mines in the Alleghany district obtained U.S. Government exploration loans. |
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| 1964 |
The Brush Creek mines, a substantial source of gold in the Alleghany district, Sierra County, ceased operations. |
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| 1965 |
Governor Edmund G. Brown signed Senate Bill 265 designating gold as California's official state mineral. The Sixteen-to-One mine at Alleghany, Sierra County, shut down at the end of the year. This was the last lode mine in the state that had been operated on a sustained basis. |
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| 1967 |
Two of three remaining dredges at Hammonton were shut down. |
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| 1968 |
The last gold dredge at Hammonton was shut down on October 1. This was the last sustained commercial gold-mining operation in California. |
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| 1968 |
The U.S. Treasury suspended purchases of newly-minted gold. the free market price rose to $44 an ounce early in 1969, falling by November to $38.50, because of greater stability in international currencies. |
