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.
Diamond mining in India
As of 2017, there was one industrial-scale diamond mine in India, the Majhgawan mine, near the town of Panna, Madhya Pradesh. The deposit is in a kimberlite or lamproite pipe 6.5 ha in area, and yields 10 carats to the ton. Mining is done by an open pit, which was 85 m deep as of 2011. Exploration drilling has established that the pipe continues down to at least 330 m. The mine is owned by the National Mineral Development Corporation (NMDC), employs 199 people, and has a productive capacity of 84,000 carats per year. The mine began regular production in 1967, and to date, has yielded slightly more than a million carats of diamonds.