a variety of clinopyroxene similar to augite but with less calcium, occurring in basalt, gabbro, and other rocks. [AHDOS

Pigeonite is a mineral in the clinopyroxene group. It has a general formula of (Ca,Mg,Fe)(Mg,Fe)Si2O6 The calcium cation fraction can vary from 5% to 25%, with iron and magnesium making up the rest of the cations.