In 1804 explorer Alexander Von Humboldt, for whom the ocean current is named, returned to Europe from a voyage to western South America carrying samples of bird guano from these islands. This particular guano source was extraordinarily rich in mineral nutrients and it soon became a sought-after commodity by British farmers. By 1840, world-class guano deposits, mostly from the Chincha Islands near Pisco, were among the most valuable mineral resources in the world:
Chincha Islands, Peru: The Illustrated London News, 1863
The Peruvian guano deposits were preserved in extremely thick beds, some over 40 meters high and were by far the highest grading in phosphate minerals, nitrates, and metal nutrients. They were the best in the world in both size and grade due to a number of factors: Remoteness and inaccessibility thus protected from predators, cold upwelling current, rich fisheries, limited land surfaces for birds to roost and nest, massive populations of boobies, cormorants, and pelicans, and cool hyper-arid climate
During the period 1840-1870 Peru’s giant deposits of dung were the developed world’s major source of nitrogen-phosphorous fertilizer and potassium nitrate (saltpeter) used to make gunpowder; they became the world’s first large agricultural mines. Giant US chemical and materials conglomerate W.R. Grace & Co. got its start by supplying Peruvian miners and shipping guano in the 1850s.
Guano deposits were so valuable at the time that the United States of America passed the Guano Act of 1856, a law giving US citizens the right to claim newly discovered guano-bearing rocks and islands as their own and authorizing the military to protect the rights of the claimant. Over 100 equatorial Pacific and Caribbean islands were subsequently claimed as US territories and a dozen are currently held including Baker Island, Jarvis Island, Howland Island, Christmas Island, Johnson Atoll, Midway Island, and Navassa Island.
As the guano trade prospered, the Peruvian government, as most governments are wont to do, borrowed against and spent vast sums of loan money from British and then French financiers before payments derived from mining and processing were received. By 1861, the country was essentially bankrupt. Spain subsequently tried to take the Chincha Islands by force in 1863-1864 but failed, and then the guano market crashed during a long global recession that started in 1870. Regardless of these events, by 1874 the Peruvian deposits were largely mined out.
Meanwhile, more easily exploited, non-organic mineral resources of nitrate were discovered and developed by Chilean and British interests in the Atacama Desert regions of Bolivia and Peru. Disputes over control of these nitrate deposits led directly to the War of the Pacific (1879-1883), in which Chile seized territorial control of the northern Atacama from both Bolivia and Peru. This action left Bolivia landlocked and Peru lost one of the most mineral-laden regions of the Earth, today hosting the world’s largest copper-molybdenum, iodine, nitrate, and lithium deposits.