WASHINGTON: Rare and expensive fragments of a Mars meteorite fell from the sky in July over Morocco, a team of international scientists confirmed on Wednesday.

A fireball in the sky was observed in a remote region of southern Morocco by nomads who tracked down fragments of the seven kilogram (15 pound) meteorite, marking only the fifth time in history that a Mars rock has been seen falling to Earth.

A team of eight experts with the Meteoritical Society analyzed the pieces and determined that they are authentic chunks of the red planet, said Carl Agee, part of the team and curator at the University of New Mexico.

"This discovery is tremendously important because of the quality of the sample," Agee told AFP.

The Moroccans who found the fragments quickly sold them to dealers, and museums scrambled to purchase them at a range of $500 to $1,000 dollars per gram, said Agee, whose museum now possesses a 108 gram piece.

The price for meteorites ranges from 10 to 20 times the price of gold.

"Some of these meteorites have atmospheric gas trapped inside glassy material. When they are heated and released in the laboratory and measured it's identical to the Mars atmosphere that all the Mars probes have measured," said Agee.

"All planets, like Venus, Mars and Earth, they have very different atmospheres," he added. "It's like a fingerprint."

The meteorite was named Tissint, and its discovery was documented in the Meteoritical Society's latest bulletin issued January 17.

"At about 2:00 am local time on July 18, 2011, a bright fireball was observed by several people in the region of the Oued Draa valley, east of Tata, Morocco," it said.

"One eyewitness, Mr Aznid Lhou, reported that it was at first yellow in color, and then turned green illuminating all the area before it appeared to split into two parts. Two sonic booms were heard over the valley."

By October, "nomads began to find very fresh, fusion-crusted stones in a remote area" about 50 kilometers (30 miles) east-southeast of Tata.

Agee said such Mars meteorite events only happen about once every 50 years, with the last such event in 1962 in Nigeria. Of about 100 Mars meteorites currently in Earth collections, only five have been seen to fall.

The first known meteorite from Mars was found in France in 1815, a specimen called Chassigny that Agee described as "probably one of the most expensive meteorites in the world."

Pieces of Mars are believed to have broken loose at some time in history when a massive meteor crashed into the surface of the red planet, sending chunks hurtling through space.

Some of the debris has moved fast enough to escape the gravitational pull of Mars and eventually fall to Earth.

Agee said scientists will examine the Moroccan meteorite for radioactive signatures left by cosmic rays, signaling how long its journey has been, possibly thousands or millions of years.