Ender Moreno looks for gold at La Culebra gold mine in El Callao, Bolivar state, southeastern Venezuela on March 1, 2017. Although life in the mines of eastern Venezuela is hard and dangerous, tens of thousands from all over the country head for the mines daily in overcrowded trucks, pushed by the rise in gold prices and by the severe economic crisis affecting the country, aggravated recently by the drop in oil prices. (Photo by Juan Barreto/AFP Photo)

Boys pan for gold on a riverside at Iga Barriere, 25 km (15 miles) from Bunia, in the resource-rich Ituri region of eastern Congo February 16, 2009. Ituri is one of many areas of the country to have experienced bitter ethnic conflict between rival tribes in recent years. Massacres have left tens of thousands dead. It is this fighting that led U.S. authorities to take the unprecedented step of naming Congo in section 1502 of the Dodd-Frank financial regulation act, which says U.S.-listed companies that source gold, tungsten, tantalum and tin from Congo or its neighbours must assure the U.S. stock exchange regulator that their business is not helping fund conflict. (Photo by Finbarr O'Reilly/Reuters)

An Indian artist gives the finishing touches to a figure of the elephant-headed Hindu god Ganesha at a workshop ahead of the Ganesh Chaturthi festival in New Delhi on September 15, 2015. The idol is meant for the forthcoming festival Ganesha Chaturthi, a ten-day long event which is celebrated all over India. During the Ganpati festival, that is celebrated as the birthday of Lord Ganesha, idols of the Hindu deity are worshipped at hundreds of pandals or makeshift tents before they are immersed into water bodies. This year, the festival starts on 17 September 2015. (Photo by Sajjad Hussain/AFP Photo)

Girls, who are part of Afghan Mobile Mini Circus for Children (MMCC), participate in a juggling competition in Kabul, Afghanistan August 12, 2015. The MMCC, founded by David Mason from Denmark, teaches cooperation and creativity to children scarred by years of war in Afghanistan. Despite the dangers, the project has grown so popular that it now runs centres in ten provinces and has hundreds of regular students. The circus makes visits to internally displaced persons' camps, schools, orphanages, and holds annual festivals. The children are taught the skills of juggling clubs, walking on stilts and acrobatics. (Photo by Ahmad Masood/Reuters)

French twins Thomas and Vincent (L) Seris take the tram in Bordeaux, November 12, 2014. Born with Xeroderma Pigmentosum (XP), the twins cannot be exposed to the sun and its ultraviolet (UV) light, which could provoke precocious cancers due to an autosomal recessive genetic disorder of DNA repair. Colloquially referred to as Children of the Night (Les Enfants de la Lune) the Seris twins are among 70 to 80 people in France who suffer from the genetic defect. The French association “Les Enfants de la Lune” reports that there are between five and ten thousand such cases in the world. Thomas and Vincent have been testing a new protective mask for the last year which is transparent and ventilated and developed by several hospitals in France. (Photo by Regis Duvignau/Reuters)

Jacob's Well is a perennial karstic spring in the Texas Hill Country flowing from the bed of Cypress Creek, located northwest of Wimberley, Texas. The twelve foot (four meter) diameter mouth of the spring serves as a popular swimming spot for the local land owners whose properties adjoin Cypress Creek. From the opening in the creek bed, Jacob's Well cave descends vertically for about thirty feet (ten meters), then continues downward at an angle through a series of silted chambers separated by narrow restrictions, finally reaching a depth of one hundred and twenty feet (forty meters). Until the modern era, the Trinity Aquifer-fed natural artesian spring gushed water from the mouth of the cave, with a measured flow in 1924 of one hundred and seventy gallons per second (six hundred and forty liters per second) discharging six feet (two meters) into the air. The spring is the greatest source of water recharging the Edwards Aquifer.

A demonstrator waves Turkey's national flag as he sits on a monument during a protest against Turkey's Prime Minister Tayyip Erdogan and his ruling AK Party in central Ankara June 2, 2013. Erdogan accused Turkey's main secular opposition party on Sunday of stirring a wave of anti-government protests, as tens of thousands regrouped in Istanbul and Ankara after a lull and trouble flared again in the capital. Police used tear gas on protesters in Ankara but the clashes were relatively minor compared with major violence in Turkey's biggest cities on the previous two days. (Photo by Umit Bektas/Reuters)