Fig. 2. SEM images of silver sulfide and native silver in the high-grade ores.

a Self-organized silver sulfide microparticle aggregates in association with anhedral acanthite. b Decoration of the surface of silver sulfide dendrites with nanoscale silver particles. c Growth of native silver accompanying the consumption of silver sulfide dendrites after ~65 minutes of exposure in a vacuum (<5 × 10^–5 mbar) at 15 kV. d Coexistence of silver sulfide nanoparticles and their aggregates, with the rectangle illustrating the location of the TEM foil (not to scale). Note that the silver sulfides locally contain minor Cu and/or Fe. Aca, acanthite; Ag, native silver; Ag-S silver sulfide nanoparticles, microparticles or dendrites; Cal, calcite; Chl, chlorite; Qz, quartz.