The lengthy and costly series of mining operations at Canyon Diablo were all undertaken in the hope of locating the “main mass” of this huge projectile and thus of opening up what might be called a cosmic-lode of quite valuable metals. Unfortunately, the miners overlooked the fact that impacts at meteoritic speeds produced almost incredible amounts of heat. Even the solid iron meteorites are vaporized and widely dispersed at the temperatures resulting from such impacts, as we have seen was the case at Wabar (see Chapter 4). So it was at Canyon Diablo. The idea of a cosmic-metal mine might at first strike some readers as too futuristic to take seriously. But the necessity for catching a core-fragment before it enters the consuming atmosphere of our planet is really nothing new. As far back as 1939, the senior author had occasion to point out that if we wish to start a successful cosmic-metal mine, we must catch our core-fragment before it is turned into unminable vapor. This point will come up again in the next chapter. [Illustration: Cross-section of Boisse’s hypothetical meteorite-planet. Fragmentation of this sphere was believed to have given rise to the following divisions of meteorites: The _iron_ meteorites came from A, the dense nickel-iron core. The stony-iron meteorites came from B, the intermediate zone of cellular nickel-iron and silicate minerals. The _stony_ meteorites came from C, the outer zone of silicate minerals in which relatively little or no nickel-iron is present. The chondrites were believed to come from the inner portion of this zone; the achondrites, from the outer portion.] There are several other theories of the origin of meteorites interesting enough to mention. The early view that the meteorites were debris thrown out by ancient volcanoes on the moon or recent ones on the earth came to be discredited largely on physical grounds. On the other hand, extremely violent _primordial_ volcanoes on the earth (not the weak ones of historic times, like Aetna or Vesuvius) could have ejected material that in much later times fell, and continues to fall back on our globe. This theory has not been ruled out and it still receives support, for example, from some authorities in the U.S.S.R. These same Russian scientists take most seriously a suggestion that the meteorites (and comets as well) were thrown out by volcanoes believed to exist on the planet, Jupiter—a theory dating back almost a century to the English astronomer, R. A. Proctor. Some scientists believe that meteorites represent the congealed remains of gaseous bolts of matter ejected by the sun. Others interpret them as fragments of comets that have been torn apart by passing too close to the sun, which is the most powerful gravitational center in the Solar System.