Rare meteorite class named after the Ivuna meteorite that fell in Tanzania in 1938. They are among the most primitive, friable (crumbly), and interesting of all meteorites, having undergone extensive aqueous alteration. They lack chondrules and CAIs as a result of this alteration, but contain up to 20% water, as well as various alteration minerals, such as hydrous phyllosilicates (similar to terrestrial clays), oxidized Fe in the form of magnetite, and olivine crystals sparsely scattered in a black matrix. They also contain organic matter, including polycyclic aromatic hydrocarbons (PAHs) and amino acids, which make them important in the search for clues to the origin of life in the universe. CIs have never been heated above 50° C, indicating that they came from the outer part of the solar nebula.
Some or all content above used with permission from J. H. Wittke.