By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
A variety of metals and nonmetals occurs in economic amounts in Madera County. In addition to gold, there are important tungsten deposits and occurrences of natural gas.
Madera County was formed from part of Fresno County in 1893, and included within the new county were nearly all the productive gold mines. Gold-quartz ore was found at or near the contact of the Sierra Nevada batholith with pre-Cretaceous schist and slate in an area that extends from Grub Gulch to Hildreth (Logan, 1950, p. 447).
In the 1950's small amounts of gold came from dredging operations along the Fresno, Chowchilla, and San Joaquin Rivers. After 1954 gold mining virtually ceased; no production was reported in 1959. Total production for the county through 1959 was 79,281 ounces, mostly from placers. It has not been possible to delineate any mining districts that have produced as much as 10,000 ounces of gold.