28Jun2012

Large Fragment of Allende Meteorite Fall - Public Domain Image

Everything was quiet in the Mexican state of Chihuahua on the night of February 8, 1969. And then… it happened. A huge meteorite, the size of a car, ripped through the atmosphere in a blaze of glory and shattered itself over the terrain.

It is known as the Allende meteorite, and it’s one of the most studied stony meteorites so far known. This carbonaceous chondrite contains nebular dust and gas formed during the early accretion of the solar system. Locked within the stone are a number of inclusions – from olivine and pyroxene to refractory elements like calcium, aluminum, and titanium. We thought we knew everything it contained… until now.

Over four decades after Allende came down to Earth, researchers have discovered a new mineral embedded in the space rock which will help tell us more about the early stages of our solar system’s formation. This new mineral is surmised to be among the oldest ever identified – a form of titanium oxide. It has been named “panguite” – a derivative of an mythological Chinese giant called Pan Gu. He was the one to separate yin from yang… and the creator of Earth and sky. According to the news release, t he mineral and the mineral name have been approved by the International Mineralogical Association’s Commission on New Minerals, Nomenclature and Classification. A paper outlining the discovery and the properties of this new mineral will be published in the July issue of the journal American Mineralogist, and is currently available online.

“Panguite is an especially exciting discovery since it is not only a new mineral, but also a material previously unknown to science,” says Chi Ma, a senior scientist and director of the Geological and Planetary Sciences division’s Analytical Facility at Caltech and corresponding author on the paper.

Panguite Inclusion - Credit: Chi Ma

The Allende meteorite is the largest carbonaceous chondrite ever found – and perhaps the most highly studied of all. It has been the target of a nanomineralogy investigation led by Dr. Ma for the last five years. During this time, nine new minerals, including panguite, have been identified in the Allende sample. These include allendeite, hexamolybdenum, tistarite, and kangite. These types of studies utilize tiny particles of minerals… and look for even smaller features within them.

“The intensive studies of objects in this meteorite have had a tremendous influence on current thinking about processes, timing, and chemistry in the primitive solar nebula and small planetary bodies,” says coauthor George Rossman, the Eleanor and John R. McMillan Professor of Mineralogy at Caltech.

By employing a scanning electron microscope on a sample of Allende, panguite was observed in an ultra-refractory inclusion. These types of minerals were first created when our solar system was forming – ahead of planets. The refractory minerals themselves are stable under extreme conditions and many researchers conclude they formed as primitive, high-temperature liquids produced by the solar nebula. Dr. Ma feels the study of panguite and other new refractory materials will help us to understand the conditions in which they formed and ultimately evolved. “Such investigations are essential to understand the origins of our solar system,” he says.

Original Story Source: Caltech News Release.

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