Photographer: Tomohiro Ohsumi/Bloomberg

Blue Flames and Volcanic Hikes: the Harsh, Spectacular World of Sulfur Mining

Sulfur—used to make fertilizer and fireworks, and to harden rubber—isn't an easy material to mine manually. But the environment it's found in can be spectacular: sulfuric gases can combust on contact with air, creating an electric-blue flame. The Ijen volcano in East Java, Indonesia is a harsh workplace for the miners who travel there daily, as well as a tourist attraction for adventurous travellers. Photography by Tomohiro Ohsumi/Bloomberg

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    A mountain guide takes a photograph of ignited gases rising from ceramic pipes built by mining companies in the 1960s, which condense sulfur on the volcano's crater.

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    A miner carries wicker baskets full of sulfur as plumes of gas rise from the crater. Though striking, the fumes are also caustic, and can cause damage to skin, lungs and eyes.

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    A man extracts lumps of sulfur from the crater at the Ijen volcano, with a mask as protection from the fumes. Many workers rely on wet rags to cover their mouths.

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    Mining on the volcano is often carried out at night, to escape the heat of the Javanese day. Sulfur occurs naturally in the environment and is among the most abundant elements in the earth's crust.

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    Some miners wear headlamps as they make the precarious trek along the volcano, bearing loads that may weigh almost as much as they do. 

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    The laborers at Ijen are among the last in the world to dig sulfur by hand. These days, most of the element is produced as a byproduct of oil and gas processing, with just 2 percent coming from mines.

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    The blue glow from the combustion of sulfuric gas makes a dazzling sight after dark. Adventurous tourists can hire local guides to make a night hike up the volcano. 

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     Lumps of sulfur are broken from the volcano's crater using a hammer. China is the world's largest importer of the yellow element, while Canada is its largest exporter.

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    A miner carries wicker baskets of sulfur as fumes shroud the Ijen volcano. Miners earn around $10-15 for a day's work, or less than 10 cents for a kilogram, according to media reports.

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    Sulfur is filtered at a processing factory. Local factories use the finished product to bleach sugar.

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    Workers remove a sheet of sulfur from the factory floor.

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    Working by moonlight. The crater contains the world's largest acidic volcanic lake, which is famous for its vivid turquoise color during the day.