Main Group Pallasites (MGP) Mineralogy: MGPs contain varying amounts of magnesium-rich olivine crystals set in a nickel-iron matrix, usually displaying an olivine-to-metal volume ratio of about 2 to 1. The olivine crystals have typical diameters of 0.5 to 2 cm, and the nickel-iron matrix displays medium Widmanstätten figures upon etching. The main group pallasites represent the most abundant class. Famous main group pallasites include Krasnojarsk, Brenham, Brahin, Imilac, Fukang, Admire, Albin and the most beautiful, Esquel.