CHONDRULE

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.