Primary and Secondary Structures - Meteorites
New England Meteoritical Services
 

Chondrules
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Figure 1. Scale bar 400 µm.   Figure 2. Scale bar 250 µm.
Exposed chondrules in matrix, Allende, CV3.   Three complete chondrules extracted from Saratov, L4.
     
     
 
"Chondrules" were first published in scientific research literature in the early 1900s.

The German mineralogist Gustav Rose first used the term "chondrules" in 1864 in his "Description and Classification of the Meteorites in the Collection at the Mineralogical Museum at Berlin," published by the Royal Academy of Sciences. These sub-to-millimeter-sized spherical objects are a key component of chondritic meteorites.

Chondrules - the formative sequence:

The formation of the proto-sun was a natural monumental process that spanned about 50 million years. It began with the gravitational collapse of a region within a large molecular cloud, forming a protostar.

Over tens of millions of years, the temperature and pressure within the proto-sun increased, eventually igniting nuclear fusion and the beginning Sun.

Chondrules are believed to have formed after the protosun formed from the disk of gas and dust (nebula) surrounding the emerging Sun, before the emerging planets.

Chondrules are primarily composed of silicate minerals, mostly olivine and pyroxene. These minerals are often surrounded by feldspathic minerals, which can be either glassy or crystalline. In addition to these main components, chondrules also contain small amounts of other minerals, including Fe sulfide (troilite), Metallic Fe-Ni, Oxides such as chromite, and Phosphates such as merrillite.

These molten droplets, condensing within the (then) solar nebula, later accreted with other materials to form the parent bodies of chondritic meteorites.

Relevant to our Sun, chondrules are composed of "first-generation" mineralogy. These minerals originated from the gases ejected during the explosions of prior first generation stars.

Chondrules are primary structures believed to be among the first solid materials to form in the early Solar System.
 
 
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Figure 3. Scale bar 1.4 mm.
Chondrules in matrix. Axtel, CV3 .
 
 
Chondrules in thin section.
 

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Figure 4. Scale bar 300 µm.   Figure 5. Scale bar 300 µm.
Barred/radial chondrule.   Complex chondrules - upper right, center. Barred chondrule upper and lower left.
     
     
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Figure 6. Scale bar 300 µm.   Figure 7. Scale bar 200 µm.
Radial chondrule, fragment - left.   Radial chondrule, partial - right.
     
     
 
 
 
 
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