In 1902 Barringer learned of the existence of a large crater, located 35 miles east of Flagstaff, Arizona. The crater, known as Coon Mountain, had previously been studied by the geologist Grove Karl Gilbert in 1891. Gilbert had hypothesized that the crater must have been the result of either a gas explosion or a meteorite. After performing experiments in the crater, however, Gilbert's conclusion was that the crater could not be the result of an impact, and therefore could only be the result of an explosion. He concluded this despite the clear presence of thousands of small meteoritic particles in the vicinity of the crater. Upon hearing of the existence of the crater and the meteoritic iron, Barringer became convinced that the crater was of meteoritic origin. With both scientific and monetary aims in mind, Barringer created the "Standard Iron Company" in order to mine the crater for the iron that he assumed must be buried below its surface. The Standard Iron Company conducted drilling operations in and around the crater between 1903 and 1905, and concluded that the crater had indeed been caused by a violent impact. It was unable to find the meteorite, however. In 1906, Barringer and his partner, the mathematician and physicist Benjamin C. Tilghman, presented their first papers to the U.S. Geological Survey outlining the evidence in support of the impact theory. The papers were published in the Proceedings of the Academy of Natural Sciences in Philadelphia. The mining of the crater continued until 1929 without ever finding the ten-million ton meteorite that Barringer assumed must be hidden. At this time the astronomerForest Ray Moulton performed calculations on the energy expended by the meteorite on impact, and concluded that the meteorite had most likely vaporized when it landed. By this point Barringer had spent over $600,000 in mining the crater, nearly bankrupting him, with no iron profits to show for it. Barringer died of a heart attack on November 30, 1929, shortly after reading the very persuasive arguments that no iron was to be found. He was survived by his wife, Margaret Bennett, and eight children, who, with their descendants, formed the , which owns the site to this day. By the time of his death, Barringer had convinced most of the scientific community that his impact theory was correct. The theory has been further confirmed with new evidence since then, most notably by Eugene Shoemaker during the 1960s. A small lunar crater is named after Daniel Barringer on the far side of the Moon.