Fig. 4From: Ooidal ironstones in the Meso-Cenozoic sequences in western Siberia: assessment of formation processes and relationship with regional and global earth processesSEM images showing evolutionary series of pyrite formation from framboid to euhedral crystal: (a) Massive pyrite microcrystals; (b) Normal framboids; (c, d) Polygonal framboids; (e) Euhedral pyrite crystalBack to article page