Rich Pedroncelli / AP

In this photo taken Thursday, Dec. 13, Sutter Gold Mining Co. mill superintendent Paul Skinner pours the first thin stream of glowing molten gold into a mold, forming a shiny one-inch pyramid, near Sutter Creek, Calif. The company announced Monday, Dec. 17, that it poured its first gold as it prepared to begin the first large-scale Sierra Nevada underground gold mining operation in a half century.

By Don Thompson, Associated Press 

The last of California's great gold mines closed a generation ago. But with the price of the metal near historic highs, hovering around $1,700 an ounce, the first large-scale hard rock gold mining operation in a half-century is coming back to life. 

Miners are digging again where their forebears once unearthed riches from eight historic mines that honeycomb Sutter Gold Mining Co.'s holdings about 50 miles southeast of Sacramento. 

Rich Pedroncelli / AP

Miner Keith Emerald uses a pneumatic drill to drill holes that will be packed with explosives to blast into the sold rock wall at the Sutter Gold Mining Co.'s mines near Sutter Creek, Calif.

Rich Pedroncelli / AP

Matt Collins, chief operating officer of the Sutter Gold Mining Co., left, watches as, from left, Allen Smith, Brain Herfel, Ted Chapman and Wayne Murphy calibrate the water flow of a gravity table at the company's newly constructed mill near Sutter Creek, Calif. The gravity table uses technology similar to those used by gold rush-era miners who used pans to separate gold from surrounding materials.

By spring, the company's 110 employees expect to be removing 150 tons of ore a day from a site immediately north of the old Lincoln Mine, enough to produce nearly 2,000 ounces of gold each month. 

Rich Pedroncelli / AP

Sutter Gold Mining Co. mill superintendent Paul Skinner removes a crucible of glowing molten gold that will be poured into a mold.

Rich Pedroncelli / AP

Sutter Gold Mining Co. mill superintendent Paul Skinner displays a four-ounce pyramid of gold he has just poured at the new mill.

Related content:

• Gold and diamond rush fuels dreams in South American borderlands
• South Sudan catches gold fever
• Philippines' black market is China's golden connection

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Jorge Silva / Reuters

An aerial view shows an illegal mine in the jungle in southern Venezuela.

Jorge Silva / Reuters

An illegal miner or garimpeiro works in a mine close to the Ikabaru river in southern Venezuela.

Jorge Silva / Reuters

Rough diamonds are seen on the desk of a trader in his office in Santa Elena de Uairen in the south of Venezuela.

In the triangle that connects Venezuela, Brazil and Guyana a huge number of illegal gold and diamond prospectors — garimpeiros — dream of changing their lives overnight by finding a huge bonanza. 

Writing on Reuters' photographers blog, Jorge Silva describes his journey to document these remote mines: 

We are just north of the Amazon Basin, riding a boat on the Ikabaru River. The passengers are people who buy gold and diamonds. They stop at each of the illegal mines that appear as craters on the river’s edge. They carry small weighing scales that seem very accurate, magnifying loupes, burners to melt the gold and separate the mercury, and some large spoons to collect it.

They are also carrying bags full of cash.

Jorge Silva / Reuters

An illegal mine is seen in the southern Venezuelan state of Bolivar, near the border with Brazil.

Jorge Silva / Reuters

A man performs maintenance while sitting on the top of an Antonov An-2 aircraft before it departs with supplies to the mines, in the town of Ikabaru in the south of Venezuela.

The appeal of working in illegal mining is enormous. Four grams of gold equal an average monthly wage in Venezuela. An ounce of the metal goes for over $1,700. The gold fever is understandable if you consider that an ounce used to sell for $250 ten years ago.

But in these mines, and the towns around them, life is expensive. A bottle of water costs around $12, and a 250-liter tank of gasoline, which would cost just $5 in the rest of the country, here goes for up to $1,200. Venezuela is known for having the cheapest gasoline in the world.

Masked men stole 70 gold bars from fishing boat in Curacao

Those who can, work hard. They don’t know if they will be able to carry on. The government is threatening to clamp down on clandestine mining. Thousands of families and whole towns live off this activity, directly or indirectly.

Jorge Silva / Reuters

A garimpeiro digs with a pressure hose in Bolivar.

Jorge Silva / Reuters

Heavily armed guards hold their weapons outside a business licensed to buy rough diamonds and gold in Georgetown, the capital of Guyana.

In a city nearby, a diamond buyer adjusted the gun on his waist while he greeted a miner who brought some “rocks.” He passionately explained that diamonds are the perfect currency. “You can carry thousands of dollars in the pocket of your pants without setting off any metal detector. There are no borders for them.”

Back at the mine, Ramón walked exhausted at the end of his workday. His face, ravaged by the sun, was sprinkled with mud. When he smiled, a golden “R” became visible, inlaid in one of his front teeth. Read the full story.

Jorge Silva / Reuters

An miner named Ramon flashes a gold letter 'R' on his tooth as he smiles after working in a mine in Bolivar.

Editor's note: Images taken in November, 2012 and made available to NBC News today.

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Adriane Ohanesian / Reuters

A Toposa boy walks along the Singaita River where gold has been found in Namorinyang, South Sudan.

Adriane Ohanesian / Reuters

A Toposa woman looks for gold in the Singaita River in Namorinyang, South Sudan.

Adriane Ohanesian / Reuters

A man digs a hole in search of gold in Napotpot, South Sudan.

Adriane Ohanesian / Reuters

A Toposa boy takes a rest after digging for gold in Napotpot, South Sudan.

Adriane Ohanesian / Reuters

A trader weighs his gold in a shop in Kapoeta, South Sudan.

Adriane Ohanesian / Reuters

A Toposa girl pans for gold in the Singaita River in Namorinyang, South Sudan.

Adriane Ohanesian / Reuters

Jackson Locheto from Kenya uses a gold detector in Nanakanak, South Sudan.

In South Sudan ordinary people have been extracting gold from artisanal mines and taking part in as-yet unregulated trade in the precious metal.

Reuters reports, dozens of Toposa tribesmen and women, festooned with plastic necklaces, brass piercings and beaded amulets, hack away at the red soil with metal poles and shovels, digging small craters in a boozy revelry.

"Everything is luck," said Leer Likuam on the edge of a shallow trench through a translator. On an average day he might dig up six grams, worth around 1,200 South Sudanese pounds ($270), he said. "Some days you're lucky."

Once he found a 200-gram gold nugget bigger than his thumb, boasts Likuam.

On the international market, Likuam's prize lump would fetch $11,000, an enormous sum in a country where the average teacher earns just 360 South Sudanese pounds, about $90, per month.

But now the government hopes to pass mining legislation that will formalize the industry, let them tax precious metal and mineral exports and sell concessions to large-scale investors. Read the complete article.

All images were captured by Reuters photographer Adriane Ohanesian in September and October 2012, but made available to NBC News today.

Adriane Ohanesian / Reuters

A shirt hangs in the window of a Sarko alcohol shop in Kapoeta, South Sudan.

Adriane Ohanesian / Reuters

A bowl holding small flakes of gold sits in the middle of Singaita River in Namorinyang, South Sudan.

Adriane Ohanesian / Reuters

A view of the Singaita River which flows down from the Lauro mountains and through Kapoeta, South Sudan.

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Erik De Castro / Reuters

Filipino miners push a cart containing sacks of mineral muck ore in the gold mining town of Diwalwal on Wednesday.

Erik De Castro / Reuters

Filipino miners use water to get gold dust from diced muck ore.

Erik De Castro / Reuters

A gold trader uses a stone to classify the grade or value of a gold nugget.

Reuters reports: Arthur Uy, who looks after Mount Diwata as governor of Compostela Valley province in southern Philippines, the top small-scale gold mining province in the Philippines, said the black market in gold is mainly based in the capital, Manila. "All the production of small-scale mines, almost all, now goes to the black market, because there is no tax in the black market," said Rex Banggawan, an accountant for a small-scale mining cooperative that buys and sells gold in the mountain city of Baguio in northern Philippines. "After that, smuggling is automatic."

"Most of the gold is being smuggled out to Hong Kong, that's the biggest market," said Uy, a two-term governor whose family of Chinese descent partly owns one of the four most productive small-scale mines on Mount Diwata. Continue reading the full story.

Erik De Castro / Reuters

A view of houses in the gold mining town of Diwalwal in Compostela Valley, southern Philippines.

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David Gray / Reuters

A small-scale miner digs a hole searching for gold on a small hill overlooking grasslands in rural Mongolia on April 4, 2012. Pictures made available on April 19.

David Gray / Reuters

Reuters reports — In a hot, concrete hut filled with acetylene fumes, an elderly Mongolian miner struggles to contain her excitement as she plucks a sizzling inch-long nugget of gold from a grubby cooling pot and raises it to the light.

65-year-old Khorloo is a member of a new Mongol horde of at least 60,000 herders, farmers and urban unemployed trying to extract the riches buried in the vast steppe with metal detectors, shovels and home-made smelters.

See more of photographer David Gray's work from Mongolia on PhotoBlog

In the last five years, dwindling legal gold supplies and a spike in black market demand from China have made work much more lucrative for Mongolia's "ninja miners" - so named because of the large green pans carried on their backs that look like turtle shells. For thousands of dirt-poor herders, the soaring prices alone are enough to justify years of harassment, abuse and hard labor. Read the full story.

David Gray / Reuters

A miner pours water into a crushing machine in an attempt to siphon gold at a processing plant around 100 km (62 miles) north of Ulan Bator.

David Gray / Reuters

A miner holds gold that was melted together at a processing plant.

David Gray / Reuters

A miner removes rocks from a hole he dug to search for gold.

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Photographer David Gray has been traveling across a small part of Mongolia, which is the least densely populated country on the planet according to figures cited by Reuters. The population of just 2.7 million is spread across an area three times the size of France, with two-fifths of Mongolians living in rural areas. 

David Gray / Reuters

Horses graze on grasslands south-west of the Mongolian capital city Ulan Bator on April 4, 2012.

David Gray / Reuters

A painting of the former Mongolian Emperor Genghis Khan hangs from the wall of a mining hut located around 62 miles north of Ulan Bator on April 5, 2012.

David Gray / Reuters

A frozen river is seen next to a group of houses located on the outskirts of the Mongolian capital city of Ulan Bator on April 3, 2012.

Reuters examines the political situation in Mongolia ahead of parliamentary elections in June: 

Mongolia sits on vast quantities of untapped mineral wealth, the exploitation of which is likely to turn it into one of the world's fastest growing economies over the next decade. 

But political uncertainty worries investors. One of the parties in Mongolia's shaky coalition government said it would pull out before the vote, and politicians are under constant pressure to be seen to getting a good deal for the country from resources investors.

The priority for Mongolia is the development of its tiny economy, and foreign investors want to know if the government can create a stable legal environment while handling the pressures exerted by impatient citizens as well as its two giant neighbours, Russia and China. Read more.

David Gray / Reuters

A herder stands on a hill overlooking grasslands south-west of Ulan Bator on April 4, 2012.

David Gray / Reuters

A dog sits at the door to a house in a small township located on grasslands south-west of Ulan Bator on April 4, 2012.

David Gray / Reuters

A woman performs a water displacement test to determine the purity of some gold that was brought in by small-scale miners at a processing plant north of Ulan Bator on April 5, 2012. The International Monetary Fund estimates Mongolia's GDP could grow as much as 10 percent this year, helped by rising gold prices but there is concern over environmental standards in the mining industry.

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Pascal Lauener / Reuters

Melted gold flows out of a smelter into a mould of a bar at a plant of gold refiner and bar manufacturer Argor-Heraeus SA in the southern Swiss town of Mendrisio, March 1.

Pascal Lauener / Reuters

Melted gold flows out of a smelter into a mould of a bar at a plant of gold refiner and bar manufacturer Argor-Heraeus SA in the southern Swiss town of Mendrisio, March 1.

Pascal Lauener / Reuters

A glowing gold bar of one kilogram falls out of a mould as a workers prepares to casts melted gold into the mould at a plant of refiner and bar manufacturer Argor-Heraeus SA in the southern Swiss town of Mendrisio, March 1.(SWITZERLAND - Tags: BUSINESS)

Pascal Lauener / Reuters

A worker puts down a gold bar of one kilogram at a plant of refiner and bar manufacturer Argor-Heraeus SA in the southern Swiss town of Mendrisio, March 1.

Pascal Lauener / Reuters

Gold bars of one kilogram each are placed on a table at a plant of gold refiner and bar manufacturer Argor-Heraeus SA in the southern Swiss town of Mendrisio, March 1.

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