Figure 1. – This is a band contrast image which results from an EBSD run, whereby every pixel has a corresponding EBSD measurement. The grey scale relates to the quality of the data measured – the brighter the area, the better the quality. Zones A-C are progressive overgrowth forms. Zone A is characterised by zoning, which is clearly depicted in CL images. Zone B is a zone of “zero solutions”(i.e., no indexing, which makes it likely that this area is SiO₂ but not quartz) and is hence black. In the CL image of this same area, definite overgrowth is displayed that is chalcedony-like in appearance. Zone C is characterised by small, euhedral quartz crystal outgrowths and zone D is porosity, filled with epoxy resin. Transect line 1 relates to Figure 2. The sample has no topography.