A train drives along a field at a salt production site at the Sasyk-Sivash lake near the city of Yevpatoria, Crimea, November 14, 2017. A saltwater lagoon known as Lake Sasyk-Sivash on Ukraine's Crimea peninsula is the source of a rare resource: pink salt. The mineral is tinted by tiny algae that produce the pigment beta-carotene. Each autumn, seasonal workers collect thousands of tons of pink salt for processing and export. (Photo by Pavel Rebrov/Reuters)

A illegal gold miner of Kamoro people, Tinus, pan for gold on February 4, 2017 in Timika, Papua Province, Indonesia. Indonesia produces over 70 billion dollars in gold a year and is home to the largest gold mine and the third largest copper mine in the world, the Grasberg mine, which is located at West Papua. (Photo by Ulet Ifansasti/Getty Images)

Workers adjust rails at the bed of a drained area of a lake used for the production of salt at the Sasyk-Sivash lake near the city of Yevpatoria, Crimea, September 25, 2015. The area has a long tradition of salt production, prepared from salt flats flooded with water from the Black Sea. (Photo by Pavel Rebrov/Reuters)

An employee walks near a rotary dredge which works on the coal face of the Borodinsky opencast colliery, near the Siberian town of Borodino, east of Krasnoyarsk, December 9, 2014. The Borodinsky colliery, 9 km (5.6 miles) long and more than 100 meters (328 feet) deep, annually produces more than 20 million tons of coal and is considered to be the biggest opencast coal mine in Russia, according to official representatives. (Photo by Ilya Naymushin/Reuters)

A miner sits front of the statue of St. Barbara, saint of the miners, during last working day at Hungary's last hard coal deep-cast mine at Markushegy December 23, 2014.The underground mine, west of the capital city Budapest, has to stop producing coal at the end of this year in line with a European Union effort to shut down uncompetitive hard coal mines. (Photo by Laszlo Balogh/Reuters)

Men work at Makala gold mine camp near the town of Mongbwalu in Ituri province, eastern Democratic Republic of Congo on April 7, 2018. (Photo by Goran Tomasevic/Reuters)

This photo taken on May 17, 2019 shows rough rubies displayed at the gems market in Mogok town, north of Mandalay. Burrowing deep underground, thousands of informal miners risk their lives to find gleaming red gems as a law change spurs opportunity in Myanmar's “land of rubies”. (Photo by Ye Aung Thu/AFP Photo)

Miners pulling up lazy tourists to the rim of Kawah Ijen (Ijen Volcano), East Java, Indonesia on September 21, 2017. They will earn as much as they would bring down a load of sulfur. Nomadic Explorer, Cultural Lifestyle Photographer Claudio Sieber captured striking images of miners working at Ijen volcanic range in East Java, Indonesia. The sulphur miners risk their lives daily as they climb the active volcano carrying heavy loads, which they sell to sugar refineries. (Photo by Claudio Sieber/Barcroft Images)