IT probably won鈥檛 start a gold rush, but the discovery that Colombia鈥檚
Mount Galeras is belching out bullion will earn the volcano a place in the
record books. Fraser Goff, an American geochemist at Los Alamos National
Laboratory in New Mexico, estimates its output at half a kilogram a day.
Goff went to Galeras in January 1993 to measure the amount of tritium in
the volcano鈥檚 magma. Soon after he arrived, the volcano erupted, killing nine
people. When Goff resumed his work, a local guide offered to show him a vein
of gold 16 kilometres west of the volcano鈥檚 summit.
Goff had samples of rock analysed. Gold turned out to be present in the
samples in concentrations as high as 269 parts per million. Other ore samples
Goff picked up around the volcano contained up to 22 ppm. And the 鈥渕agmatic
fluid鈥� 鈥� the liquid that condenses from the gases that belch out of the
volcano鈥檚 fumaroles 鈥� contained up to 0.04 ppm.
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Based on estimates of the amount of gas the volcano gives off, Goff
calculates that Galeras puts out 鈥渁 pound of gold a day鈥�. This makes the
mountain the world鈥檚 top gold-producing volcano 鈥� although, as Goff points
out, not many of the world鈥檚 volcanoes have been investigated too closely.
Galeras throws out up to twenty times as much gold as Mount St Helens in
Washington state, and roughly four times as much as Mount Erebus in
Antarctica.
Goff kept mum about his findings until last week, when he revealed all at a
meeting of the Geological Society of America in Seattle. 鈥淚 knew there would
probably be staking and claiming going on if I didn鈥檛,鈥� he says.