Terra Cotta, California
Coal, along with clay deposits, was found on the site by John D. Huff in the late 1880s, and the Southern California Coal and Clay Company was formed to mine them. The town site of Terra Cotta was laid out and was given a post office on October 26, 1887. In May 1893 its post office was closed and moved to Lake Elsinore. A plant for the manufacture of sewer and water pipes was built using the coal to fire ceramic pipes in the four kilns. The finished product had to be shipped by wagon six miles through Lake Elsinore to the La Laguna rail station at the mouth of Railroad Canyon until 1896 when a spur line was built through Lake Elsinore and Terra Cotta to the new clay deposits in Alberhill. The coal mined was also used locally as fuel for the stamping mill at the Good Hope Mine and was shipped elsewhere in the state.
Ub, Serbia
The following table gives a preview of total number of employed people per their core activity (as of 2016):
There are several mines and resource centers of coal (Radljevo field - 344,000,000 tones, Zvizdar field - 280,000,000 tones), clay, sand, stone and limestone.
The biggest producer of quartz sand in Serbia is "Kopovi a.d.", with overall production of over 400,000 tones per year. 
Clay pits are based below the layers of sand and quartz sand. Municipality of Ub is the biggest supplier of high-quality clay in Serbia. There are more than 1,800,000 tones of clay.