Meteorites Meteorites constitute the oldest material available for study in the laboratory, older than any rocks on Earth. Meteorites are pieces of rock and metal that fall to Earth from space. They are fragments broken from asteroids. The composition variation spans a whole range of planetary materials, from completely unmelted and unfractionated stony chondrites to highly fractionated and differentiated iron meteorites. There are also stony/iron meteorites. Some come from non-asteroidal sources, e.g., planets. These materials, and the components within them carry records of all stages of Solar System history. Study of meteorites allows a more complete understanding of the processes undergone by the material that resulted in today's Earth. They are the only physical objects (except some lunar rocks) that can be analysed directly in the laboratory; hence, they are an unparalleled resource for Solar System exploration. Meteorites mark the change that took place between simple aggregates of interstellar dust and their accumulation into parent bodies as a protoplanetary disk formed and then evolved into the Solar System. Mineral assemblages in chondrites trace the composition of the solar nebula; interstellar grains yield evidence about the Sun's galactic neighbourhood. Melted meteorites record the extent, timing and duration of melting and subsequent magmatic activity on their parent asteroids. Iron and stony-iron meteorites act as reference materials for the study of planetary core formation. Lunar meteorites extend the range and diversity of materials available for study from Earth's only natural satellite, whilst the families of martian meteorites assist in interpretation of magmatic and fluvial processes on Mars, and have stimulated studies into the potential existence (extinct or extant) of life on Mars. Past and future space missions to comets, asteroids and Mars rely on measurements from meteorites to aid in interpretation of returned data. Astronomers studying interstellar and circumstellar dust by both ground- and space-based techniques are turning more frequently to results from meteorites, and the interstellar grains separated from them, to help with understanding the size, shape and composition of the dust. Meteorites, then, provide the "ground truth" for theoretical, observational and exploration studies of the Solar System.

A meteorite discovered at La Criolla, Argentina, 6th January 1985. Its total weight is more than 35 kg.