|Name: ||NWA 7397|
|Weight: ||623.95 grams|
|Specimen: ||End Cut|
|Location: ||Northwest Africa|
|Classification: ||Basaltic Shergottite|
|Date: ||Found - June 2012|
|TKW: ||2,130 grams*|
Found in 2012, this unpaired Martian basalt is magnesium rich, implying an origin that was deep within Mars.|
The reverse is blanketed in fusion crust, an artifact of the meteorite's fiery descent through Earth's atmosphere (where temperatures reached during frictional heating are hotter than the surface of the sun!).
For more information see the entry in the Meteoritical Bulletin.
*BACKPLATE owns the main mass in addition to approximately one kilo of more recently acquired fragments. It is estimated that the total weight of NWA 7397 — plus the as yet to be assigned designation for the fragments — is well less than 5 kilos.
Photo Credit: © Heritage Auctions
© Heritage Auctions
Intro to Meteorites
Meteorites have held the fascination of mankind since the dawn of civilization. Dozens of meteorites are known to have been venerated and every major religion has a parable seeded by a meteorite impact.
Meteorites — not to be confused with meteors, the luminescent phenomena in the night sky — are fragments of natural material from outer space that impact Earth. Named after the closest city, geological feature, or post office to which they are “delivered,” meteorites originate from asteroids, comets, the Moon and Mars. Unlike meteor showers, which result from Earth's predictable, annual passage through cometary tails, meteorite showers are almost never predictable.
Meteorites are of great interest to scientists as they contain a tremendous amount of information concerning the formation of our solar system. In addition, it has been hypothesized not only that a meteorite led to the demise of the dinosaurs (allowing the opportunity for human life to evolve), but also that meteorites transported to Earth the precursors to life itself, more than four billion years ago. Organic molecules, including amino acids, have been found in some meteorites, resulting in the increasingly popular Panspermia Theory of Creation: life having been “seeded” on Earth by extraterrestrial impact.
The combined mass of all known meteorites is less than the world’s annual output of gold, and private collectors have been making the little excess material that does exist into one of the most in-demand collectibles today.
There are three broad categories of meteorites: stones (representing approximately 94% of all meteorites), irons (5%); and stony irons (1%). Stone meteorites quickly terrestrialize or become "weathered" after impact. To the uninitiated, stones typically appear to be of an Earthly origin, and recovery is problematic unless the impact is witnessed or the meteorite lands in an environment where it is easily detected. Iron meteorites are comprised primarily of iron and nickel, are more resistant to Earth’s elemental forces and are more easily recognized. On average, they are composed of 90% iron, 8% nickel, and 2% trace elements. The amount of nickel determines the type of crystalline pattern that will form, referred to as either a Widmanstätten or acid-etch pattern. This singularly dazzling crystalline latticework is unique to meteorites, and therefore diagnostic in the identification of meteorites.
Stony-irons, as the name indicates, are a combination of the stone and iron types and the most resplendent of all, frequently containing crystals of translucent olivine suspended in a nickel-iron matrix.
For a meteorite to be analyzed by scientists it must be broken or cut; only when multiple specimens of the same meteorite are recovered can complete specimens exist. In the event you have found what you believe to be a meteorite, you are urged to contact a sanctioned meteorite identification service, as each newly discovered meteorite is a possible Rosetta Stone that can assist in unlocking the mystery of creation.
Scientists agree that the impact of a large asteroid on the Martian surface launched chunks of Mars into space — portions of which landed on Earth. There are numerous compositional and isotopic features that are unique to Mars — which assists scientists in the determination of Martian origin. Several samples are known to contain tiny bubbles...with tiny volumes of gas...which match the composition of the Martian atmosphere as determined by NASA's Viking missions.
As of June 1, 2012, there are only 61 different Martian meteorites known to exist. The number would be somewhat larger if we included those meteorites which are found at different times in a similar location, which are later determined to originate from the same impact event. The total weight of every Martian meteorite known to exist is approximately 115 kilograms or 250 pounds. (By way of comparison, 2500 tons of gold as well as 8 tons of gem quality diamonds are mined every single year.) Clearly, specimens of the planet Mars are among the rarest objects on Earth. Moreover, of the 250 pounds of Martian material in existence, 60 pounds (nearly 25%) is forever off-limits to the private sector as it was recovered in Antarctica on scientific expeditions and controlled by a consortium of governments.
Specimens of the planet Mars are among the rarest and most unobtainable substances on Earth. Unlike the 841 pounds of lunar specimens recovered by NASA's Apollo astronauts, the only samples of Mars are meteorites.
Proof of Martian Origin
The scientific community universally agrees that as of June 1, 2012, there are 61 distinct Martian meteorites whose total weight is less than 250 pounds.
In 1995, Science magazine announced that minute volumes of gas trapped in tiny bubbles found within a suspected Martian meteorite matched the atmospheric composition of Mars (as determined by NASA's unmanned Viking lander in 1976). Prior to the announcement of this smoking gun of Martian origin, the belief that a select group of meteorites originated from Mars was based on the following:
Scientists were puzzled by a handful of meteorites which contained minerals that could only form following water alteration. As there is no water in the asteroid belt — the source of 99% of all meteorites — they did not originate in the asteroid belt. In addition, these meteorites not contained evidence of having crystallized under the influence of a planetary-sized — yet smaller than Earth's — gravitational field, and also contained levels of cosmic radiation consistent with having originated in the inner solar system. As a result of the foregoing, scientists were certain that such meteorites originated from Venus or Mars, and were believed to be Martian as it would be more difficult for an object to escape the Venusian surface after an asteroid impact given that Venus has a stronger gravitational field and thicker atmosphere. And so for decades this small class of meteorites was suspected to have originated from Mars — and then the aforementioned proof arrived.
In the past twenty years the highly specific chemical signature of Martian meteorites has been further studied and refined with ever improved technology, and further links to Mars have been established.