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Elizabethan gold riddle solved
Mineral of the Month: Titanium


Elizabethan gold riddle solved

The year was 1576. Sea captain Martin Frobisher set off from England in search of a northwest passage to China. When Frobisher and his crew hit the Canadian Arctic, they stalled in the ice and were forced to turn back. Before they left Canada, the crew gathered some black rocks that resembled sea coal (used to heat English homes), to prove to Queen Elizabeth I that they had found new land. Legend has it that when burned in a hearth, the black rocks changed into a golden color. Although tests on the black rocks were inconclusive at best, with merely a hint of gold, the queen and other investors commissioned Frobisher and crew to return to the new land to harvest gold. Two years and boatloads of ore later, English assessors concluded that the black rock contained no gold. Now, 400 years later, an archaeologist and a geochemist say that this was no accident — it was the first gold swindle in the New World.

On a tiny island in Canada, researchers excavate the remains of the ore-processing shops used to test supposedly precious-metal bearing ore by a British exploration team in 1578. Researchers have recently determined that the British team defrauded its investors in Canada’s oldest mining scandal. Image courtesy of Réginald Auger.

Over the years, only two plausible explanations for the gold scandal have been purported, according to an article by archaeologist Réginald Auger and geochemist Georges Beaudoin, both with Laval University in Quebec City, in the June Canadian Journal of Earth Sciences. Either the alchemists accidentally contaminated the rock samples with gold and silver while processing the ore, or they forged the results and defrauded their investors.

When Frobisher and his crew returned to the Arctic, they set up a camp on a tiny island off Baffin Land in Nunavut “where they found a vein of black ore — and where they were separated from the Inuit,” Auger says. They built two ore-processing shops with clay ovens that alchemists used to test for the presence of precious metals in the ore, in a process called assaying, he says. On visits to the tiny island, Laval and Smithsonian Institution archaeologists have found not only food such as dried peas and bread left by the 1578 Frobisher expedition, but also assay “shots,” or little beads of lead left over from assaying.

It was these lead beads that drew Beaudoin into the mystery. At the time, the preferred assaying method involved placing lead and smelting ore with the ore sample in a crucible in a very hot oven. The lead, acting as a sponge, would join to the precious metals and sink to the bottom of the crucible, in a process similar to that used today, Beaudoin says. Assayers recognized that the process often introduced low levels of contaminants (which could include gold or silver) into the ore, so it was possible that this “swindle” could merely have been an accident. Thus, Beaudoin and Auger devised a test to sample the lead beads.

They analyzed the chemical composition of five lead samples from Frobisher’s crucibles, and also combed the archaeological and historical literature to find all they could about the assaying results from 1576 through 1578. Their chemical analysis showed that four of the five samples contained no gold, and the fifth contained negligible amounts, Beaudoin says. “Our evidence shows no indication that this was an accident,” he says.

Furthermore, Beaudoin says, the host rock was black amphibolite — not a stone commonly associated with gold. Amphibolite, a metamorphic rock consisting primarily of amphibole and plagioclase, is typically derived from basalt. Unless hydrothermally altered, the amphibolite would be unlikely to contain any significant amount of gold, says Brent Owens, a petrologist at the College of William and Mary in Williamsburg, Va. Additionally, amphibolite does not resemble coal, other than in color, Owens says, so “fraud seems like a good conclusion in this intriguing old detective story.”

All the signs, Auger says, point to fraud. In addition to lack of evidence of accidental contamination, there is a lot of historical “contradictory evidence” that should raise some red flags, he says. First, out of three original tests, two proved inconclusive for gold. Second, all of the assaying log books were allegedly lost out of a porthole at sea, so when Frobisher’s assay team returned to England, investors could not see what had been discovered in Canada. Additionally, it is well-known that people at the time would occasionally salt ore samples with gold — even coins — to obtain funding for exploration, Auger says.

The parallels between this case and Canada’s 1997 Bre-X gold scandal, where the company had salted its gold samples and vastly overstated the value of its gold deposit in Indonesia, are striking, Beaudoin and Auger say. In both cases, there were clear indications that the reported amounts of gold were suspicious. And, they write, “power and greed were likely the ultimate reasons for not objectively assessing all assay results.”

Megan Sever

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Mineral of the Month: Titanium

Joseph Gambogi, the titanium commodity specialist for the U.S. Geological Survey, has compiled the following information on titanium, the ninth most abundant element in Earth’s crust.

From paint to airplanes, titanium is important in a number of applications. Commercial production comes from titanium-bearing ilmenite, rutile and leucoxene (altered ilmenite). These minerals are used to produce titanium dioxide pigment, as well as an assortment of metal and chemical products.

Globally, about 95 percent of titanium mineral production is used to produce titanium dioxide pigment. The refractive index and resulting light-scattering ability of titanium dioxide pigment produce excellent opacity and brightness. Consequently, titanium dioxide pigment is important in the production of coatings (including paint, varnish and lacquer), as well as in the paper and plastic industries. The pigment is also used in catalysts, ceramics, textiles, rubber, floor coverings, printing ink and roofing tiles.

Aside from titanium dioxide production, other titanium compounds play an important role in many industrial processes. For example, titanium trichloride is used as a catalyst for polypropylene polymerization. Barium titanate and strontium titanate are used in electronic components, whereas potassium hexafluorotitanate is used in production of titanium aluminum master alloys. Titanium nitrides and carbides are used to form corrosion- and wear-resistant coatings.

The major use for titanium metal is in commercial and military aerospace components. Other purposes of titanium metal include automotive exhausts, bicycle frames, golf clubs, heat exchangers, military armor, medical implants, sporting goods and submarine hulls. Historically, fluctuations in the aerospace industry have resulted in cyclic demand for titanium metal. In 2002, global production of primary metal was about 72,000 tons, whereas domestic consumption was 17,300 tons. Research and development programs, such as the Defense Advanced Research Projects Agency’s Titanium Initiative, may lower the cost of titanium metal production.

The steel and nonferrous alloy industries also consume titanium metal. In steelmaking, titanium is used for deoxidation, grain-size control, carbon and nitrogen control, and stabilization. When used in aluminum alloys, titanium improves casting and reduces cracking. In 2002, the estimated use of titanium by these industries was 8,000 metric tons.

World production of titanium-bearing minerals in 2002 was about 4.7 million metric tons of contained titanium dioxide. Domestic consumption was about 1.4 million metric tons. Major sources of titanium minerals included Australia, Canada, India, Norway, South Africa and Ukraine.

For more information on titanium visit minerals.usgs.gov/minerals.

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