Seven years ago, according to local legend, an impoverished vegetable farmer named Susyono found a gram-sized gold nugget on the sparsely vegetated Gunung Botak, or Bald Mountain, one of the highest features of eastern Indonesia’s one-time prison island of Buru.
Within months, the island had been overrun by more than 130,000 artisanal miners flocking in from the surrounding Moluccan islands and other far-flung parts of Indonesia in a gold rush reminiscent of the United States and Australia in the late 1880s.
Over the next four years, using huge quantities of mercury to separate out the gold, the makeshift miners turned the mountain slopes into a toxic wasteland, leaching the deadly heavy metal into the island’s floodplain and posing a significant threat to agriculture, marine life and public health.
The Maluku government finally managed to evict most of the illegal miners in 2015, but as is so often the case more than 2,000 have now filtered back, reportedly under the protection of senior police and army officers and other vested interests who benefit from the gold trade.
In August, authorities on the island seized 171 drums of cyanide, which is also commonly used to extract gold from low-grade ore. But mercury has always been the preferred method at the hundreds of illegal mine sites across resource-rich Indonesia.
According to one recent study, the mercury found in some of Gunung Botak’s waste sediments was 682 milligrams (mg) a kilogram, compared to 19 to 908 milligrams taken in the 1960s around Japan’s contaminated Minamata Bay, from where the crippling disease associated with mercury poisoning gets its name.
Buru joins other provinces like North Sulawesi, Jambi, Central Kalimantan, North Sulawesi, Southeast Sulawesi and Lombok where as many as 200,000 people are believed to be suffering from birth deformities and nervous disorders that characterize mercury poisoning.
Less well known is the fact that Buru may also be the third biggest gold find since the discovery of Freeport McMoRan Copper & Gold’s Grasberg mine in Papua, which after nearly 30 years of mining still contains reserves of 67 million ounces, and Sumbawa’s near-exhausted Batu Hijau mine.
The only preliminary geological study done on Gunung Botak has never been publicly released, but it indicates the deposit may contain more than 20 million ounces of gold in the resource at a depth below 50 meters — beyond the reach of rudimentary surface caving.
Measuring 2.5 kilometers long and up to 400 meters wide, samples from the mountain system have produced results as high as 150 grams a ton – twice that found at the incomparable Grasberg, which remains the world’s biggest gold deposit.
“It is the richest epithermal gold vein I have ever seen,” says the veteran foreign geologist who carried out the rare on-site appraisal in 2012 and has spent the past three decades exploring for minerals from Australia to Mongolia.
During the 1960 and 1970s, Buru was a notorious internment camp for 12,000 political prisoners, all of whom them accused without trial of belonging to the outlawed Communist Party of Indonesia (PKI), crushed in a bloody purge that cost more than 500,000 lives.
The last prisoners, including the late celebrated writer Pramoedya Ananda Toer, were released in 1979, leaving the island to lapse back into isolated anonymity, home to a population of 160,000 eking out a living as fishermen and subsistence farmers.
The gold discovery in 2011 changed all that. Lying at the eastern end of the 8,473-square-kilometer island, Gunung Botak was quickly overrun, with most of the mine workings concentrated around the small village of Wamsait at the confluence of two rivers.
Typically, hundreds of small mobile ball-mills known as trommels were used to grind down the ore, during which flecks of gold adhere to the mercury. The resulting amalgam is then heated with a blowtorch, releasing deadly vapors that do the most damage to human health.
Over time, according to a November 2017 article in the Journal of Degraded and Mining Lands Management, mercury contamination from the rock waste, known as tailings, drained into the three surrounding sub-districts of Waelata, Waeapo and Namlea.
An earlier study led by Amanda Reichelt-Brushett, from Australia’s Southern Cross University, found the highest concentrations of mercury in waste ponds with heightened levels in sediments from the Wamsait River and where it empties into nearby Kayeli Bay.
Although preliminary, that 2013 investigation raised concerns about the long-term distribution of the heavy metal and how it would ultimately affect the rice-growing floodplain to the south of Gunung Botak and fish stocks around Buru and neighboring Ambon.
Imported mercury has been used at 850 illegal mining sites across Indonesia since the late 1990s, with armies of illegal miners often driving legitimate gold-mining companies off their concessions, particularly where surface deposits are easy to reach.
In some places, up to 100 tons of mercury has been dumped into the environment by the estimated 250,000 artisanal miners who are believed to be active at any one time across the resource-rich archipelago.
The Trade Ministry was supposed to have banned imports in 2014, but last year Indonesian environmental NGO BaliFokus claimed Indonesia had instead become one of the world’s largest mercury producers, exporting 635 tons to 13 countries in 2015-2016.
It is not clear what the future holds for Buru, but when the government called tenders to clean up the mine site, BaliFokus founder Yuyun Ismawati says the project stalled after the successful company spent all its time looking for gold instead.
Last year, with President Joko Widodo seeking to impose a nationwide ban on the use of mercury, Indonesia finally ratified the Minamata Convention on Mercury, a global treaty which took effect in 128 other countries four years earlier.
But health and environmental experts say that may not be enough when many of the illegal sites are under the control of powerful political figures, supported by local elements of the police and military who all get a cut of the profits from an illegal industry that nets as much as US$5 billion a year.