Goldbugs have a new prospecting tool: the horsetail weed (Equisetum arvense) which grows abundantly across the U. S. and Canada. When it grows in soil with a gold content, it hungrily absorbs the metal. Last week Hans Torkel Fredrik Lundberg of Toronto told the American Institute of Mining and Metallurgical Engineers that for some time Canadian prospectors had been locating gold by burning a clump of horsetail, analyzing the ashes.
Called geobotany by Engineer Lundberg, this method of prospecting was developed in Sweden. Tin, nickel, silver copper, many other metals can also be located by plant absorption.
Concentration of gold (if any) in horsetail ash will be far higher than in the soil it sprouted from. Hence it is practical in some cases to harvest and replant horsetail weed over low-grade surface ore fields rather than mine them. And seed selection may breed a still more efficient horsetail. At present a ton of horsetail from low-grade gold fields will yield as much as 4½ oz. of gold, worth $157.50. Value of a ton of good timothy hay: $7.78.