The Earth Story

The Allende meteorite

The Allende Meteorite is the largest of its kind ever found on Earth. It is often referred to as the most widely studied meteorite in history. The fall of this meteorite was viewed in Chihuahua, Mexico in the early hours of February 8th, 1969.

It is a carbonaceous chondrite (most primitive type of meteorites), a class of *chonditic meteorite. The meteorite is quite distinguished due to the high quantity of calcium-aluminium-rich inclusions (CAI).

Allende hit Earth only a few months prior to the Apollo 11 mission. As one can imagine, it was an exciting time for numerous scientists. Many labs and museums dispatched teams to site to collect samples of the meteorite. The Smithsonian Institution was one of them.

The **chondrules and CAIs found in Allende are approximated to be 4.57 billion years old.

The age of this type of meteorite is often taken as the age of the Solar System due to the fact that they have experienced the least mixing since the formation of the Solar System itself.

*Chondritic – chondrite – non-metallic meteorites that haven’t been altered due to melting of the parent body.

**Chondrules -molten or partially molten droplets. Found in chondrites.

Note. Calcium-aluminium-rich inclusions are part of the oldest substances created in our Solar System.

By

Renesh T

Image source:

http://bit.ly/1a3ogeo

Check out a similar article we’ve done earlier:

NEW PRIMITIVE MINERALS DISCOVERED WITHIN METEORITE - TEL

http://on.fb.me/1Mh52CI

References/Further reading:

http://bit.ly/1BxK4V5 http://bit.ly/1BSdop2 http://bit.ly/1HUSQ7K

CAIs

This is a slice of a meteorite known as Allende, a carbonaceous chondrite that fell from the sky over Mexico in 1969. Allende is one of the most heavily researched meteorites in history because it is a large sample, with abundant material available to send to labs, because it fell in early 1969 just as labs were gearing up to process samples from the Apollo program, and because it preserves chemical evidence of the formation of the solar system.

There are so many papers out on samples like Allende that it’s hard to pick just one component to look at. The spherical objects are called chondrules; they’re the remnants of silicate minerals that melted and formed blobs out in space. The dark groundmass is carbon-rich, containing even complex organic molecules. But take a look at the irregular white patches; that’s the component I want to focus on today.

The irregular white patches are made of minerals such as anorthite, melilite, perovskite, aluminous spinel, and hibonite. Those minerals have a couple chemical components in common, including calcium and aluminum, as well as a bit of titanium.

These components tell a story of condensation in the early solar system. At some point, the materials in the inner solar system were heated so much that everything was vaporized. If you vaporize every element on the periodic table then slowly cool it, each element will come out of the gas and form a solid at a distinct temperature –called the condensation temperature of that element.

Although there are 90 elements found in nature, only a handful of these are abundant enough to dominate the chemistry of the rock. The first moderately abundant element to condense from a rock vapor is titanium; the next abundant elements to form are aluminum and calcium.

The Calcium and Aluminum Rich Inclusions (CAIs) found in a meteorite like Allende are therefore the remnants of the first solids to form in the inner solar system. The white bits of this rock formed solids when it was too hot for most other minerals to form, so they literally are the oldest part of our solar system. Some of these CAIs have a bit of uranium in them as well and therefore they can be dated; age dates on these grains push the origin of the solar system all the way back to 4.568 billion years ago.

-JBB

Image credit: http://bit.ly/1Y6Tbsu

References: http://s.si.edu/1TrwIqY http://bit.ly/1LScdQJ

The Allende meteorite

The Allende Meteorite is the largest of its kind ever found on Earth. It is often referred to as the most widely studied meteorite in history. The fall of this meteorite was viewed in Chihuahua, Mexico in the early hours of February 8th, 1969.

It is a carbonaceous chondrite (most primitive type of meteorites), a class of *chonditic meteorite. The meteorite is quite distinguished due to the high quantity of calcium-aluminium-rich inclusions (CAI).

Allende hit Earth only a few months prior to the Apollo 11 mission. As one can imagine, it was an exciting time for numerous scientists. Many labs and museums dispatched teams to site to collect samples of the meteorite. The Smithsonian Institution was one of them.

The **chondrules and CAIs found in Allende are approximated to be 4.57 billion years old.

The age of this type of meteorite is often taken as the age of the Solar System due to the fact that they have experienced the least mixing since the formation of the Solar System itself.

*Chondritic – chondrite – non-metallic meteorites that haven’t been altered due to melting of the parent body.

**Chondrules -molten or partially molten droplets. Found in chondrites.

Note. Calcium-aluminium-rich inclusions are part of the oldest substances created in our Solar System.

By

Renesh T

Image source:

http://bit.ly/1a3ogeo

Check out a similar article we’ve done earlier:

NEW PRIMITIVE MINERALS DISCOVERED WITHIN METEORITE - TEL

http://on.fb.me/1Mh52CI

References/Further reading:

http://bit.ly/1BxK4V5 http://bit.ly/1BSdop2 http://bit.ly/1HUSQ7K

NEW PRIMITIVE MINERALS DISCOVERED WITHIN METEORITE A new mineral, a titania named panguite, was found within the Allende meteorite using a scanning electron microscope. The International Mineralogical Association’s Commission on New Minerals, Nomenclature, and Classification has approved the new mineral and its name. The Allende meteorite fell to Earth in Mexico in 1969 and through nanomineralogy investigations has yielded the discovery of 9 new minerals including panguite by geologist Chi Ma of the California Institute of Technology (Caltech), USA. The name panguite is a reference to Pan Gu, a giant from Chinese mythology who created the world by separating the heaven and earth from chaos in the beginning. Panguite, along with the minerals kangite, tistarite and allendeite, was one of the first solid materials to form in our solar system, about 4.567 billion years ago. The mineral’s chemical name is (Ti4+,Sc,Al,Mg,Zr,Ca)1.8O3; it contains oxygen, magnesium, aluminium, titanium, calcium, scandium and zirconium. The presence of zirconium in particular will aid scientists in discovering more about the environment before and after the solar system’s formation. Panguite was first observed under a scanning electron microscope in an ultra-refractory inclusion embedded in the meteorite. The term refractory here means that these inclusions contain minerals that are stable at high temperatures and in extreme environments; therefore more likely to have formed as primitive, high-temperature liquids produced by the solar nebula. The Allende meteorite is the largest carbonaceous chondrite ever found on Earth and is very well studied. The image is an enlarged backscatter image showing the area where panguite crystals occur with smaller Zr-rich panguite in davisite. Davisite, CaScAlSiO_6, is a new member of the Ca clinopyroxene group, from the Allende meteorite. The mottled appearance of the davisite mostly reflects differences in Sc concentrations. -TEL http://www.wired.com/wiredscience/2012/06/new-mineral-panguite/; http://mr.caltech.edu/press_releases/13524; http://ammin.geoscienceworld.org/content/97/7/1219.full?ijkey=G2n1UMXmu7r4.&keytype=ref&siteid=gsammin