Norite

Image Source: www.SandAtlas.org

Igneous rock composed of 90% plagioclase, 95% orthopyroxene (low-Ca pyroxene) and less than 10% olivine. Norite is most commonly found in the lunar (highlands) meteorites but has also been found in about a dozen diogenites, a few shergottites, and a very small number of other achondrite types.

If the norite or gabbro contains between 10% and 90% olivine, then the prefix “olivine” should be added to the name: olivine norite and olivine gabbro. Once the norite or gabbro composition exceeds 90% olivine, the rock is considered troctolitic.