Mineral Benches: A California History is a series exploring the industrial uses and historical relevance of minerals that have shaped San Francisco. For MSPF 2015, we’ve constructed the first bench, “Gold.”

-Sabrina Habel, Mary Anne Kluth, and FICTILIS

Gold: a California History

4474952699_5d326a5918_oSan Francisco first boomed in population because of the Gold Rush, when nearby gold mineral deposits were found in 1848 in Coloma, California.  Now that San Francisco is again a boomtown, fueled by neighboring Silicon Valley’s technology economy, much of its population relies on the minerals embedded in digital devices (tin, tantalum, tungsten, and gold, among others). Both gold and digital devices are status items contributing the rumor of fantastic riches long associated with the dream many people share when moving to San Francisco.

The Gold Rush of 1848 was the largest mass movement of people in the Western hemisphere, and was the foundation for the following decades of growth in the region. Gold was first discovered in Coloma, CA, in the South Fork of the American River, a valley known as Cullumah by the Nisenan Indians. Many gold panners ended up settling in California after the rush, after discovering the productive, fertile ground for agriculture – California’s true gold.

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Discovery of the Butte Nugget

Earlier this year, the “Butte Nugget”, a 6.07 pound gold nuggets and one of the largest found in recent years, was discovered in Butte County and sold for $400,000 to an anonymous Bay Area collector. During the Gold Rush, prospectors unearthed large nuggets in California, including a 54-pound chunk found in Butte County in 1859, but it has been decades since one this large has been found. “Nuggets like this don’t come along every day,” said David McCarthy, the nugget’s appraiser. “I really didn’t believe that I would see a California nugget of this size unearthed during my lifetime.”



Neo-Alchemy (from Yes, Science Has Found Bacteria That Makes 24-Carat Gold by Liz Klimas)

A team at Michigan State University has landed on a gold mine — albeit on the micro scale. They call it “microbial alchemy.” Using the extremophile bacteria Cupriavidus metallidurans — a microbe that can grow in harsh, metallic environments – Kazem Kashefi, assistant professor of microbiology and molecular genetics, and Adam Brown, associate professor of electronic art and intermedia, have found that it can produce 24-carat, nearly 99.9 percent, pure gold. In a statement about the findings from the university, Kashefi said they are literally “transforming gold from something that has no value into a solid, precious metal that’s valuable.” The men gave the bacteria “unprecedented amounts” of gold chloride, which is a toxic chemical compound, and found not only do the microbes thrive on it, but they can produce gold in a relatively quick manner. Unfortunately, the gold-producing bacteria are not going to solve economic crisis or make the men rich. Only producing a gold nugget in a week, bringing operations to a larger-scale production is not cost-effective. The university news release also states that the researchers have questions about the ethics of their findings as it relates to “greed, economy and environmental impact.”

gold-producing-bacteria_1-620x413Gold bits produced by the bacteria. (Photo: G.L. Kohuth via


“In very rough numbers, there are 10 troy ounces of gold (or about three-fifths of a pound) per ton of smartphones. Ten thousand phones weigh one ton.”

-Sean Magann, SIMS Metal Solutions

Gold Recovery:

Instructables User Josehf Murchison created a tutorial for recovering gold from used electronics from PCI cards, IC pins, and to phones and printers. After three months of work, Josehf recovered 576.5 grains of gold from electronics ($1500 worth) by collecting, stripping, and dissolving (in a mixture of muriatic acid and hydrogen peroxide) electronic parts.


photo: Josehf Murchison @

Gold in the DRC

In the eastern Congo, Gold is a primary source of income for armed groups. It’s easy to smuggle across borders – according to the Enough Project ~$30,000 worth of gold can fit in one’s pocket and around $700,000 in a briefcase.

“The essential revenue for armed groups comes from gold today. Of course there are other sources like logging, but gold has become the primary source for groups like the FDLR,” said Fidel Bafilemba, Enough’s researcher in eastern Congo.

In the first half of 2012, 23 kilograms of gold were officially exported from eastern Congo while 2-4 tons of gold went out through illegal routes – amounting to lost revenues of hundreds of millions of dollars, and instead, the profits from gold benefiting armed groups through illegal trade.

1871875063_e1b6780e07_o1873328054_c2767cdc7d_oJulien Harneis (Creative Commons)



“A lot of the responsibility for gold now lies with the jewelry industry, which consumes about 50% of the world’s gold.”(“Amid legal uncertainty on conflict minerals, alternatives emerge” Allison Moodie, The Guardian. Full text here.)

To date, an estimated five million people have died in the Democratic Republic of Congo in the war, primarily fueled by goal mining and smuggling. (Conflict Minerals in Your Mobile—Why Congo’s War Matters. Sri Jegarajah, CNBC Asia Pacific. Full text here.)