Pennsylvania State University
Earth and Mineral Sciences Museum
122 Steidle Building, University Park, Pennsylvania 16802
(814) 865-6427 FAX (814) 863-7708
Andrew A. Sicree, Curator
Click here for a written summary of this project. FOR IMMEDIATE RELEASE:
PENN STATE RESEARCHERS PLAN RECOVERY OF FOSSIL IRON METEORITES FROM COAL
STATE COLLEGE, PA, JULY 25, 1996: Geologists at the Pennsylvania State University in State College, Pennsylvania, recently developed a strategy for harvesting "fossil" meteorites from coal employing "tramp" iron magnets currently in use at coal mines. Andrew Sicree and David Gold of the Geosciences Department of the Pennsylvania State University theorize that iron meteorites which fell into ancient coal swamps will be preserved in the coal. Discovery of such meteorites would be an important advance for the geological sciences.
Meteorites have fallen to Earth throughout geologic time, but fossil meteorites (i.e., those which fell millions of years ago and have been preserved in sedimentary rocks) are quite rare. Iron meteorites oxidize rapidly, surviving only a few hundred to a few thousand years in most environments. Only a few "fossil" meteorites with terrestrial ages in terms of millions of years are known and their discoveries were matters of shear chance.
An iron meteorite falling into a coal swamp will develop a rind of pyrite which inhibits alteration of the interior of the meteorite. After coalification, an iron meteorite encased in coal will be preserved from further corrosion by the reduced state of the coal, particularly in a coal seam with a methane-dominated vapor phase.
Estimates of the present-day flux of meteorites range from 100 to 1000 metric tons of meteorites per day for the whole of the Earth's surface, about 1% of which is recoverable. About 5% of these meteorites are strongly magnetic (i.e., iron, or stony-iron meteorites). If coal accumulated at the rate of about 1 meter per ten thousand years, then every million short tons of coal could yield up to 300 g of magnetic meteorites. A large Pennsylvania coal operation which mines about 3 million tons of coal per year, for instance, could yield about 900 g of magnetic meteorites per year, while a large Wyoming coal mine moving about 30 million tons per year could produce approximately 5 to 10 pounds of iron meteorites or more each year.
Finding such meteorites is difficult, but Sicree and Gold have begun an international effort to search for meteorites by examining magnetic materials pulled out of coal by "tramp iron" electromagnets. Many coal mines and processing plants suspend these electromagnets over their conveyor belts to remove tramp iron (such as bulldozer teeth) from their coal in order to protect their crushers. Many of these magnets are also ideally designed for picking up any fossil iron meteorites which might be in the coal. Sicree and Gold note that many coal operators may already be unknowingly recovering iron meteorites and disposing of them with their scrap metal. Such meteorites may be difficult to recognize: they may be rusty, or they may be coated with pyrite or an iron carbonate mineral. In some cases the original iron-nickel metallic structure of the meteorite may be almost completely corroded away.
Enlisting coal miners and coal processors is important to the success of this project. Sicree and Gold ask that coal miners and coal processors examine the output of their tramp iron magnets when cleaning the magnets (in the case of mines using manual-clean magnets) or when emptying their scrap iron bins (in the case of self-cleaning magnets). Anyone who finds an unusual object in coal is encouraged send it to Sicree and Gold at Penn State University for examination.
Andrew Sicree and David Gold may be reached at the Geosciences Department, Penn State University, 122 Steidle Building, University Park, PA 16802, USA, (814) 865-6427, or via Email: email@example.com.