Figure 3: TEM images.
(a) Coesite in the silica grains entrained in shock veins (Fig. 1b) is assemblages of nano-size crystals. (b) Seifertite in the silica grain is rhomboid or spindle-shaped. Inserted selected area electron diffraction (SAED) patterns correspond to seifertite. (c) Thin stishovite platelets are stacked in cristobalite in the silica grains far from the shock vein. Inserted SAED patterns show {011}cri//{201}sti. (d) Seifertite and fragments consisting of cristobalite + stishovite coexist in intricate arrangements in the area between the seifertite-dominant and stishovite-dominant portions. Cri, cristobalite; Coe, coesite; Sti, stishovite; α-PbO2, seifertite; SiO2-Gla, silica glass.
