Talampaya

March's Meteorite of the Month is Talampaya, an achondrite that fell in Argentina, in 1995.

According to the Meteoritical Bulletin (MB 83): 

Stories circulating among meteorite dealers tell of a meteorite that fell in Argentina, producing a sonic boom that scared a mountain climber. The climber eventually found the meteorite somewhere down range. The location of the fall may have been in San Juan or La Rioja province.  One 1421 gram stone was recovered, and sold in the United States.

Talampaya is a cumulate eucrite, and part of the HED (Howardite-Eucrite-Diogenite) meteorite group, believed to have formed on the surface of asteroid 4-Vesta.
Talampaya

Photo © ASU/CMS/Garvie.

Eucrites are the most common type of achondrite meteorite falls (vs. finds) and are believed to have formed from the cooling of magma on the surface of the Asteroid 4-Vesta; the number 4 refers to Vesta being the fourth asteroid ever discovered, in March of 1807, by German astronomer Heinrich Wilhelm Olbers.

In September 2007, NASA launched the Dawn mission to study Vesta and the dwarf planet Ceres to provide insight into the formation and evolution of solid bodies in the early solar system, using a visible camera, a visible and infrared mapping spectrometer, and a gamma ray and neutron spectrometer.

Dawn stayed in orbit around Vesta for a year, thoroughly studying the asteroid's geology, chemistry and more; insights gained there helped build the link between Vesta and the howardite-eucrite-diogenite (HED) class of meteorites. 

Nakhla

Nakhla is a martian achondrite that fell June 28th, 1911, in Al Buhayrah, Egypt.  Nakhla is one of only 5 martian meteorites to be witnessed as it fell to Earth.

At the time of the fall, a newspaper article was published claiming the meteorite had hit a dog on entry.  This was never proven, but did inspire a Peanuts cartoon strip, in which Linus and Charlie Brown discuss the meteorite striking a dog, to Snoopy’s dismay.

Members of the Center for Meteorite Studies are interested in deciphering the geologic history and evolution of Mars through trace element and isotopic studies of the martian meteorites, and Nakhla has been actively studied by Center researchers, including:

  • Determining redox conditions in the mantle and crust on Mars through studies of rare earth element abundances, as well as the early differentiation history of Mars through investigations of the 146Sm-142Nd and 182Hf-182W short-lived isotope systems in the martian meteorites.
  • Constraining the composition of aqueous crystal fluids on Mars through analysis of the boron isotope composition of the Nakhla meteorite.
  • Utilizing the hydrogen isotope composition of the martian meteorites, determined using secondary ion mass spectrometry, to provide unique insights into the history of water on Mars and alteration of the martian crust.

Nakhla is the namesake for the nakhlite meteorite type group, made up of 14 distinct meteorites, and defined by the Meteoritical Society as clinopyroxenites or wehrlites formed as cumulate rocks.

Currently,  Ph.D. candidate Curtis Williams is analyzing the lithium isotope composition of the martian meteorites, while Ph.D. candidate Prajkta Mane and M.S. student Kera Tucker are

Photo by L. Garvie, © ASU/CMS.

Nakhla

Norton County

Norton County fell February 18th of 1948, on the Kansas/Nebraska border. 

Norton County is a rare type of meteorite called an aubrite, which is an enstatite achondrite. Aubrites are dominated by enstatite – a pyroxene mineral containing Mg, Si, and O. This mineral is white in Norton County, as opposed to the more normal green to brown, because it contains so little iron – in fact the iron content is so low that this meteorite fluoresces under a blacklight (see photo, below).

Aubrites are so reduced that they contain minerals not found, or rare, on Earth, including :

  • Caswellsilverite NaCrS2
  • Daubréelite FeCr2S4
  • Oldhamite CaS
  • Perryite (Ni,Fe)5(Si,P)2
  • Schreibersite (Fe,Ni)3P

Spectral studies link the aubrites to a few near-Earth Apollo asteroids, specifically 3103 Eger and 434 Hungaria. Further spectral work is consistent with asteroid 3103 Eger as the source of the aubrites.

Over one ton of the Norton County meteorite has been recovered to date.

Photo: Norton County meteorite under black light. Photo by L. Garvie and © ASU/CMS.

Norton County

Camel Donga

Camel Donga is an achondrite found on the Nullarbor Plain of Western Australia in 1984.  The word "donga" is a term for "campsite" in Australia.

Camel Donga is a eucrite (monomict breccia), part of the HED group of meteorites (Howardites-Eucrites-Diogenites).  These meteorites are believed to originate from the cooling of magma on the surface of asteroid 4-Vesta. 

Photo © ASU/CMS.

Camel Donga