Fig. 1

Preparation of lamellae prepared from dust particles by FIB milling and TEM analysis. a Selection of dust particle based on SEM–EDS analyses. Inset shows a deposition of carbon layer on the selected particle. b Gallium ion beam milling. SEM image. Arrow indicates the direction of ion beam. c Electron-transparent lamella. TEM image. d Analyses of internal microstructures. TEM image. e Mineral identification by electron diffraction (inset) and lattice imaging. f Mineral identification and chemical analysis by EDS. Cc = carbon coating, Gc = gold coating, Ss = substrate (conductive carbon tape). SEM images were obtained at 15 kV using a TESCAN MIRA 3XMH field emission SEM. FIB milling was carried out by a Helios 650 instrument. TEM images were acquired using a JEOL JEM 2010 and a JEOL JEM ARM 200F instruments