ASTRONOMY - GEOLOGY Meteorites . . . (See two pictures below) During the past five years, there has been a rapidly increasing demand from universities and planetary scientists for freshly fallen meteorite material. The result has been an increasing cost to acquire rocks from space, which translates into big bucks for those little shooting stars you see at night. If you know what to look for, they can, literally, become dollars from heaven. Meteorites are remnants of other worlds, pieces of comets or asteroids blown apart by collisions with each other or, in some cataclysmic cases, with the Earth. These pieces of rock or iron (or both) which survive their fiery plunge through our atmosphere can create huge craters like the one near Winslow, Arizona (See picture below). This crater, nearly a mile in diameter and 600 deep, was created in 10 seconds, about 50,000 years ago by a 100-foot diameter chunk of iron and nickel traveling about 40,000 mph. This hyper-rock created an unimaginable explosion, most of it disintegrating upon impact, but throwing small pieces over a 12 mile area. There are more than 15 known impact craters throughout the U.S. from which fragments are still being found by treasure hunters, hikers and off-road vehicle enthusiasts. There are locations where meteorites have exploded or fragmented at high altitude and dispersed pieces over a wide area, known as a strewn field. These zones can cover just a couple of square acres (Holbrook, Arizona) or several thousand square miles (Nambia, Africa). Such areas may contain pieces barely distinguishable from surrounding rocks, or they may stand out like a sore thumb, as on a dry lake bed or wide expanse of desert. The fragments may range in size from 1 gram to 1 ton and have high levels of iron or barely a trace. (Magnets will be attracted to 95% of all meteorites, so that is a simple preliminary test you can make in the field.) Most meteorites that have recently arrived on Earth will have a dark brown or black fusion crust on their surface, the result of a high-speed entry into the atmosphere. Newly identified falls are of great interest to researchers and scientists who can study the sample before it has rusted or become contaminated with terrestrial pollutants. One of the most famous, if not the most valuable meteorite to be scrutinized by NASA and the news media, was found in Antarctica (Allan Hills) in 1984, which after recent reexamination with electron microscope was found to have possible fossilized materials believed to have come from the planet Mars. METEOROID - Still in space METEOR - In the atmosphere METEORITE - After it strikes the ground If you happen to be ice-biking, or 4-wheeling or prospecting near glaciers or ice fields, keep in mind that solitary rocky material is seldom found embedded in ice, and if you see one, it could be a rare kind of meteorite. Some museums and universities have paid from $100 to $5,000 per gram for this particular (Allan Hills 840001) specimen, but most iron meteorites are sold or traded by collectors from 10 cents to $1.50 per gram, depending upon their variety, authenticity and size. Like gold nuggets, the price is determined by the market -- sometimes a feeding frenzy develops over a particular stony-iron, or recently acquired one-of-a-kind meteorite.
Posted on: Tue, 29 Oct 2013 14:58:43 +0000
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