|an extraordinary or unusual thing, person, or event; an exceptional example or instance.|
|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
|chondrule (kŏn'drl) Pronunciation Key
A small round granule of olivine or pyroxene occurring in many stony meteorites. Chondrules are thought to have formed from the condensation of hot gases in the solar system.
small, rounded particle embedded in most stony meteorites called chondrites. Chondrules are usually about one millimetre in diameter and consist largely of the silicate minerals olivine and pyroxene. From textural and chemical relationships, it is clear that they were formed at high temperatures as dispersed molten droplets, which subsequently solidified and aggregated into chondritic masses. This process occurred in space in earliest times before the planets accreted. How the chondrules were melted, however, is not understood. It seems likely that dust particles or planetesimals already in existence were melted by high-energy events such as high-velocity collisions and splashed about as droplets that quickly cooled and crystallized
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