Diogenites belong to the evolved achondrite HED group that also includes howardites and eucrites. They are named after the Greek philosopher Diogenes of Apollonia, of the 5th century BCE, who was the first to suggest that meteorites come from outer space (a realization forgotten for over 2,000 years). They are composed mostly of Mg-rich orthopyroxene (En67-77), with minor amounts of olivine (Fa27-35) and plagioclase (An60-91). Pyroxene is usually coarse-grained, indicating that diogenites represent intrusive rocks that formed in magma chambers within the deeper regions of the parent body of 4 Vesta or possibly other Vestoids. The Tatahouine meteorite, a unique diogenite that fell in Tunisia in 1931, is renowned for its green, centimeter-sized pyroxene crystals.
Some or all content above used with permission from J. H. Wittke.