Backscattered electron (BSE) images showing cristobalite textures in thin section. a) Cristobalite crystal showing typical ‘fish-scale’ cracking in MVO1236. The boundary between the fish-scale cristobalite and surrounding groundmass is unclear. One platy crystal is protruding from a pore to the right, centre of the image; b) ‘Feathery’ groundmass texture (indicated by arrows) in MVO617, composed of cristobalite, glass and plagioclase feldspar (Horwell et al.
) with associated fish-scale cristobalite which, in this case, is probably a product of extensive devitrification and also has a diffuse boundary.