Why did some gold prospectors strike it rich with a bonanza gold vein, while others came up empty-handed? The credit may go to nanoparticles.
New research reveals that high-grade veins of gold contain clusters of gold nanoparticles, which is important because it explains how these impossibly rich aggregations of gold can form in fractures below the earth. Laboratory experiments have long found that it's impossible to dissolve enough gold in hydrothermal fluids to ultimately crystallize out to form thick, high-grade veins of the glittering stuff. Hydrothermal fluids are heated liquids, warmed by magma in the earth's crust, which carry complex stews of dissolved minerals and gases.
The new study, which was published May 18 in the journal Proceedings of the National Academy of Sciences, suggests that these veins don't come from dissolved gold at all. Instead, they may be accumulations from so-called colloidal fluids, in which the particles of gold aren't dissolved, but instead suspended.
