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Chondrules in the chondrite classification Grassland. A millimeter scale is shown. Chondrules in the Carbonaceous Chondrite NWA 13887. A chondrule (from Ancient Greek χόνδρος chondros, grain) is a round grain found in a chondrite. Chondrules form as molten or partially molten droplets in space before being accreted to their parent asteroids.
Evidence suggests the main growth of asteroids can result from gas-assisted accretion of chondrules, which are millimeter-sized spherules that form as molten (or partially molten) droplets in space before being accreted to their parent asteroids. [34] In the inner Solar System, chondrules appear to have been crucial for initiating accretion. [35]
Type 2 chondrites are those that have experienced extensive aqueous alteration, but still contain recognizable chondrules as well as primary, unaltered olivine and/or pyroxene. The fine-grained matrix is generally fully hydrated and minerals inside chondrules may show variable degrees of hydration.
Aqueous alteration promotes a composition of hydrous phyllosilicates, magnetite, and olivine crystals occurring in a black matrix, and a possible lack of chondrules. It is thought they have not been heated above 50 °C (122 °F), indicating that they condensed in the cooler outer portion of the solar nebula.
Primitive achondrites are a subdivision of meteorites.They are classified on the same rank (historically called "Class") and lying between chondrites and achondrites.They are called primitive because they are achondrites that have retained much of their original chondritic properties.
EH (high-iron) chondrites contain small chondrules (~0.2 millimetres (0.0079 in)) and high ratios of siderophile elements to silicon. Somewhat more than 10% of the rock is composed of metal grains. A diagnostic feature of EH chondrites is that the Fe-Ni metal contains ~3 wt% elemental silicon.
NGC 3132 (also known as the Eight-Burst Nebula, [2] the Southern Ring Nebula, [2] or Caldwell 74) is a bright and extensively studied planetary nebula in the constellation Vela. Its distance from Earth is estimated at 613 pc or 2,000 light-years .
Ordinary chondrite NWA 3189 sliced. Field of view c. 2.2 cm across. NWA 3189 has been classified as an LL3.2–3.4 ordinary chondrite ("LL" means very low total iron content; "3" refers to well-preserved chondrules – the rock has not been subjected to metamorphism intense enough to disrupt the chondritic texture).