Chondrites are stony (non-metallic) meteorites that have not been modified due to melting or differentiation of the parent body. They are formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids. They are the most common type of meteorite that falls to Earth with estimates for the proportion of the total fall that they represent varying between 85.7% and 86.2%. Their study provides important clues for understanding the origin and age of the Solar System, the synthesis of organic compounds, the origin of life or the presence of water on Earth. One of their characteristics is the presence of chondrules, which are round grains formed by distinct minerals, that normally constitute between 20% and 80% of a chondrite by volume.Chondrites can be differentiated from iron meteorites due to their low iron and nickel content. Other non-metallic meteorites, achondrites, which lack chondrules, were formed more recently.There are currently over 27,000 chondrites in the world's collections. The largest individual stone ever recovered, weighing 1770 kg, was part of the Jilin meteorite shower of 1976. Chondrite falls range from single stones to extraordinary showers consisting of thousands of individual stones, as occurred in the Holbrook fall of 1912, where an estimated 14,000 stones rained down on northern Arizona.