Thursday, August 11 2005 09:59 Hrs (IST) - World Time -

Ahmedabad: Elaborate tests conducted on a meteorite fragment, which fell in Rajasthan recently, has revealed it to be a very rare iron meteorite showing significant radioactivity.

Tests were conducted by scientists of the Phyical Research Laboratory (PRL) and Basic Sciences Research Institute (BSRI) on the meteorite, which fell at Bhuka village in Barmer district of Rajasthan on June 25, this year.

"The results of our study indicate that it is a rare iron meteorite having a significant radioactivity of 54 Mn (Manganese) and 57 Co (Cobalt)," said Narendra Bhandari of BSRI.

"It seems to have originated from the asteriodal belt between Mars and Jupiter and might have been 100 times bigger than the its present size weighing about 2.5 kilograms," the scientist said adding that tests were still to be conducted to arrive at the estimated time the body took to travel from the belt to earth.

The meteorite, which fell in the farm of Mubeen Sindhi with a loud cracking sound and made a crater of about half-a-metre, is actually an alloy of iron and nickel, said Bhandari.

"It is the first iron meteorite to fall in Rajasthan among the seven falls in the past 15 years," he said explaining the rareness of the cosmic object.

The iron meteorite is the rarest of the three kinds of meteors, the other two being stony meteors and stony iron meteors, he said.

"Moreover, the radioactive isotopes of cobalt and manganese found together in the meteorite is also rare and is perhaps the first one to be found on earth," Bhandari added.

"We were able to detect the radioactivity because the meteorite was sent to us immediately after it fell," he said adding, "Radioactivity slowly wanes away with the passage of time."

"About 80 per cent of most meteors entering the earth's atmosphere burn out. What makes iron meteorite rare on earth is because unlike stony meteores they have a tendency to completely burn out," said Bhandari who is also the President of International Lunar Exploration Working Group (ILEWG).

The meteorite has a thick black crust with occasional golden or brownish tinge. The crust also has well developed regmaglypts (thumb marks formed when the meteorite enters earth's atmosphere) typical of meteorites.

"The tests conducted on a piece of the meteorite sent to PRL (a large chunk was sent to the Geological Survey of India), also found it to be made of pure iron which was very different from the kind of iron found on earth which usually exists as oxides," he said.