Mineral Crystallisation in Chondrules (Di - An - Fo including binary systems)

Chondrules are mafic, magmatic systems. Chondrule crystallisation can be described in e.g., the petrologic ternary phase diagram Diopside-Anorthite-Forsterite. In brief, and only the most typical path: most chondrules start deep in the forsterite primary phase field. A melt then develops towards either the Fo+An or Fo+Di cotectic line, from where on the respective two minerals crystallise unit reaching the eutectic point. There, the 3 phases Fo+Di+An crystallise together until all melt is consumed. Fractional crystallisation is qualitatively identical. The final paragenesis is in accordance with typically observed parageneses of chondrules, which is olivine+pyroxene+feldspar, and the occasional spinel, indicating – at least in these cases – an initial melt closer to the Fo-An binary. For a more complete description, the ternary phase diagram Forsterite-Anorthite-Quartz should also be consulted.