Denver, Colo. -- Looking for a meteorite is like looking for a needle in a haystack. Looking for fossil meteorites, which fell in the distant past and are now embedded in sedimentary rock, is even more difficult, but Penn State researchers think they have a way to pare down the haystack.
"There are very few known fossil meteorites," says Andrew A. Sicree, Penn State graduate student and curator of Penn State's Earth and Mineral Sciences Museum. "In collections worldwide, there are less than 20 meteorites that fell to Earth more than two million years ago. Many meteorites are recovered from Antarctica, but almost all fell in the last million years. If we could find a reliable source of old meteorites, they would begin to tell us something about our solar system in the distant past."
Sicree, Dr. David P. Gold, professor of geosciences, and Kevin Hoover of EES Environmental Group suggest that working coal mines might be the place to find fossil meteorites in good condition. Tramp-iron magnets already in use at coal mines could already be picking up iron meteorites, the researchers told attendees today (Oct. 28) at the Geological Society of American conference in Denver.
Coal mines use large magnets to remove iron from the coal stream to protect equipment down the line. Most of the iron removed is from hardened steel tools that break or otherwise fall in with the coal.
"We thought, maybe the magnets are already doing the job and we just don't know about it," said Sicree. "Hopefully, all we have to do is look in the tramp metal bins next to the magnets."
After they began visiting coal mines and talking to miners in Wyoming and Montana, they realized that often there were no bins next to the magnets and the iron removed from the coal stream was immediately thrown out or, if it was stored, was not sorted before it was sent to a reclaimer.
"So far, no iron meteorites, or other types of meteorites have been found in coal mines," says Sicree. "However, as we talk to miners and mine owners, they seem willing to save whatever the magnets collect."
Meteorites come in three general types -- stones, stony-irons and irons. Only 5 percent of meteorite falls are strongly magnetic and many of these begin to rust away once they hit the Earth's surface. The researchers believe that iron meteorites that fell during the Pennsylvanian age, 275 to 310 million years ago, and were incorporated into coal seams might be better preserved because they were sealed off from the atmosphere when they fell into the swamps that eventually became the coal beds.
"Like other people, miners bring things they've found to the museum, thinking they are meteorites," says Sicree. "We haven't found meteorites yet, but we've only just begun to search."
The researchers hope that miners and mine owners will send them any objects which are picked up by their tramp metal magnets, yet are obviously not man-made. To this end, the researchers are contacting mining professionals and distributing information, including a poster, on this project which is funded by the NASA's Pennsylvania Space Grant Consortium.
Looking at the coal removed from mines will allow screening of large amounts of rock and provide a greater chance of finding a meteorite. The researchers have also begun looking at other mining operations, such as those for salt, limestone and trona -- a sodium carbonate mineral.
EDITORS: Mr. Sicree may be reached at (814) 865-6427 or firstname.lastname@example.org Dr. Gold is at (814) 865-3934. Mr. Hoover is at (307) 683-2831.