orthoquartzite

Noun

orthoquartzite (countable and uncountable, plural orthoquartzites)

1. A very pure quartz sandstone composed of usually well rounded quartz grains cemented by silica.
   • The contact with the Fountain is sharply defined, since they consist essentially of fine-grained red or pink to white sandstone, at time cemented to an orthoquartzite—a process still continuing.1928, A. J. Tieje, “The Red Beds of the Front Range in Colorado: A Study in Sedimentation”, in The Journal of Geology, volume XXXI, page 199
   • A similar phenomenon on a smaller scale occurs at Hole-in-the-Wall, where beds of orthoquartzite show large bulbous projections on their undersides which appear to squeeze out the underlying shale.1957, Keith A. W. Crook, “Cross-Stratification and Other Sedimentary Features of the Narrabeen Group”, in Proceedings of the Linnean Society of New South Wales, volume LXXXII, page 162