Interstitial silica cement in quartzites. (a) Ribboned syntaxial overgrowths (thin section, crossed nicols). (b) Silica laminae with feathery or flamboyant quartz arranged perpendicular to the detrital quartz grains (arrows). Thin section, crossed nicols. (c) Syntaxial ribboned overgrowth (cathodoluminescence image). (d) Concentric cutans progressively filling pores (cathodoluminescence image). (1) detrital quartz grain; (2) quartz layers; (3) residual pore. After Thiry and Maréchal, (2001).