EETA79001

EETA 79001, also known as Elephant Moraine 79001, is a Martian meteorite. It was found in Elephant Moraine, in the Antarctic during the 1979–1980 collecting season.

The meteorite is classified as a shergotite and is primarily basaltic in composition. EETA 79001 is the second largest Martian meteorite found on earth, at approximately 7900 grams, only the Zagami meteorite is larger. It is a very young rock, by geologic standards, dating to only about 180 million years ago, and was ejected from the Martian surface about 600 thousand years ago.

EETA 79001 was discovered at the Elephant Moraine, near Reckling Peak, Victoria Land, Antarctica. It was especially significant due to the fact that it had glass inclusions that were found to contain rare nitrogen isotopic compositions. These same compositions were measured in the Martian atmosphere by the Viking spacecraft in 1976. This match was some of the first crucial evidence to positively identify the EETA 79001 meteorite, and others of its class, to be of Martian origin. EETA 79001 was considered to be proven of Martian origin, after much debate, in 1985 by R.O. Pepin by comparing and expanding findings of the Viking and further isotopic analysis of EETA 79001.

Stony Martian meteorites, as a whole, are described as being part of the "SNC" group of rocks. This stands for shergottites, nakhlites, and chassignites. These meteorites are distinguished by their shared isotopic compositions which are common with Martian composition, and differ from Earth compositions.

The meteorite is made up of two distinct lithologies, designated as lithology A and lithology B. Lithology B is an igneous melt, almost certainly originating deep in the Martian crust. Lithology A has some uncertainty associated with it, but appears to be made up of shocked, impact melt from the collision that caused the ejection of EETA 79001.

The meteorite is a nearly completely crystalline rock, with a composition typical of volcanic lava crystallized from molten silicate. The sample closely resembles that of basalts collected from Earth and the Moon. Close examination of this sample shows glassy feldspar, which can be shown to have formed under unique conditions, common with impact shock. This glass retains its original structure, showing evidence for no flow having occurred. This process is likely caused due to intense shock waves, such as a large meteoric impact.

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