Laboratory simulation of Mg-rich ferromagnesiosilica dust: The first building blocks of comet dust

We will focus on Mg-rich ferromagnesiosilica principal components (PCs) in the matrix of collected interplanetary dust particles to address the question: “Are these components the original presolar and nebular dust or are they made from precursor dust(s)?” Non-equilibrium condensation experiments show they are fused agglomerates of amorphous MgSiO and FeSiO silicate condensates with unique metastable eutectic compositions. While the dust condensates were not preserved, the PCs survived secondary processing comet nuclei and primitive asteroids wherein they were stored for the last 4.5 billion years.