Fig. 2: Red Lake electrum nanoparticles in amorphous carbon.
From: Nanoparticle suspensions from carbon-rich fluid make high-grade gold deposits
a High-Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) image of the Red Lake foil showing elongated inclusion at the surface of the foil, mainly composed of quartz (Qz) and an amorphous carbon phase (aC); the rest of the foil comprises coarse gold; the top of the foil is covered by a protective platinum (Pt) layer. b Energy-dispersive X-ray spectroscopy (EDS) elemental map overlaying a HAADF-STEM image from the middle of the inclusion, indicated by white rectangle in Fig. 2a; electrum nanoparticles (NPs) are encapsulated in a carbon-rich phase. c TEM image of the area marked by white rectangle in Fig. 2a; the inclusion is composed of an amorphous carbon phase (light grey) containing sub-rounded NPs (darker grey). Two large, “bubble”-like features correspond to cavities within the amorphous phase. d, e High Resolution TEM (HRTEM) image of areas marked by black rectangles in Fig. 2c showing electrum NPs with sizes varying from 4 to 10 nm. The FFT collected from the largest NP confirms a d-spacing of 2.34 Å, corresponding to Ag or Au or Ag-Au alloy.
