A very rare type of achondrite meteorite, named after the 4-kg meteorite that fell at Chassigny, France, in 1815. Only three examples are known. The chassignites (also known as olivine achondrites) are olivine-rich rocks that resemble lunar and terrestrial dunites in texture and general mineral composition but contain olivine of higher iron content. The Chassigny meteorite itself contains 92% olivine. It has a formation age of 1.3 billion years and an exposure age of about 11 million years. The chassignites belong to the class of SNC meteorites, which are thought to come from Mars.