Hrtem studies of subsolidus alteration, weathering, and subsequent diagenetic and low-grade metamorphic reactions. (Volumes I and II)
The structure of a new TiO$\sb2$ mineral that forms submicroscopic lamellae in anatase was determined by high-resolution imaging, image simulation, electron diffraction, and distance-least-squares refinement. The new mineral has previously been reported as the synthetic polymorph TiO$\sb2$ (B). In situ heating experiments revealed that TiO$\sb2$ (B) converts to anatase by growth of subnanometer-high ledges parallel to their interface. TiO$\sb2$ (B) was also identified as a minor constituent of the anatase-dominated assemblage produced by perovskite weathering. Topotactic relationships and structural considerations suggest that Ca-leaching and framework collapse via closely related reaction mechanisms leads alternatively to anatase of TiO$\sb2$ (B)
Thesis, Dissertation, English, 1990