Fig. 4
From: Fe(II) reduction of pyrolusite (β-MnO2) and secondary mineral evolution
Scanning electron micrographs reveal significant changes in particle morphology that occur when unreacted pyrolusite particles (a) are exposed to aqueous Fe(II). After one reaction sequence of pyrolusite with 3 mM aqueous Fe(II) extensive rod-like surface precipitates (b) cover the surface of every particle that was imaged. Images of particles resuspended two (c) and three (d) times in 3 mM aqueous Fe(II) show a morphological transition from rod-like precipitates to spherical particles. Scale bars in all images are 2 µm