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Chondrules
are not found
in terrestrial rocks.
Left and next picture
Dar al Gani 862, H3 |
The average chondrule size is millimeter in diameter, but it is not uncommon to have chondrules between 7 or 8 millimeters in diameter.
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Chondrules are made of olivines and pyroxenes,
as well as iron and magnesium rich minerals.
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| Silicon-oxygen, iron and magnesium represent more than 90% of the chemical components of chondrites. This elemental composition is very near the composition of the Sun, if we except the light elements (hydrogen, helium).
"What is interesting about chondrules is that radiometric dating has put them among the first solids to have formed in the solar nebula. That is, they are the first things to have "frozen" out of the interstellar gas that eventually became our solar system. So by understanding the processes that affected chondrules, we'll gain insight as to what processes were taking place as solids first formed in the solar nebula which could have determined how the nebula as a whole evolved over time."
Fred Ciesla, http://www.lpl.arizona.edu/~fciesla/work/chondrule/
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Up, right and the four pictures below.
New meteorite from Hammada al Hamra
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Metallic rim encircling chondrule
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 porphyritic chondrules :
angular crystals composing the interior.
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Chondrules
can be and usually are
modified by the thermal
or chemical history
of a meteorite.
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Also by shocks between asteroids.
Glassy shock veins
traversing a chondrule.
Dar al Gani 606
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In rare cases of very low metamorphism,
metal is present in the chondrule.
Dar al Gani 632
LL3.2-3.4 unequilibrated
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They are little rocks from space,
they are fragments of our universe.
The majority of chondrites reside within the asteroid beld and bear witness to the early history of the solar nebula.
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Carbonaceous chondrites, considered the most primitive meteorites,
are thought to have been formed in a cold oxygen rich environment.
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CO3 - Dar al Gani 749
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White metal (left) and
green gemlike inclusions (right)
in CO3 chondrules
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Chondrules are both rare
and beautiful.
Chondrules bear witness to the formation of our solar system.
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