chondrules


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chondrules

(kon -droolz) Near-spherical bodies composed chiefly of silicates, with sizes between 0.2 mm and 4 mm, found embedded in chondrites. They are usually aggregates of olivine, (Mg,Fe)2 SiO4, and pyroxene (Mg,Fe)SiO3. They may also be single crystals, wholly glass, or crystal and glass, in a wide range of proportions. They appear to have been free fluid drops made spherical by surface tension and then solidified and crystallized. There is a possibility that these silicate drops were produced by lightning discharges in the dusty primitive solar nebula or that they are crystallized droplets of impact melt produced when two asteroids collided. Chondrulelike bodies have been found in lunar soils.
References in periodicals archive ?
Generally, chondrules are made up of minerals rich in silicon, but the chondrules we found in this meteorite are completely different in that they are composed of sulfide minerals," she explained.
Our discovery of the sulfide chondrules will help us put a quantifiable number on how much sulfide was enhanced in that region of the protoplanetary disk," Miller added.
These sulfide chondrules help us pin down when and where that sulfur enhancement occurred and help us better understand the process," she added.
The new experiments probe magnetic minerals in chondrules never measured before.
My modeling for the heating events shows that shock waves passing through the solar nebula is what melted most chondrules," Desch explained.
There are other ideas for how chondrules might have formed, some involving magnetic flares above the solar nebula, or passage through the sun's magnetic field.
This reinforces the idea that shocks melted the chondrules in the solar nebula at about the location of today's asteroid belt, which lies some two to four times farther from the sun than Earth now orbits.
One perplexing aspect of this scenario, notes Alexander, is the proposed formation of inclusions and the earliest chondrules about 3 million years before asteroids.
The origins of chondrules, which are typically about a millimetre across, are shrouded in mystery.
But, calculations on the retention of sodium by the chondrules suggest they formed in dense swarms.
Collisions between such magma balls would breach their thin crusts of solid rock, spraying molten material into space, where the droplets would quickly cool to form chondrules.