protoquartzite

protoquartzite

[¦prōd·ō′kwȯrt‚sīt]
(petrology)
A well-sorted sandstone that is intermediate in composition between subgraywacke and orthoquartzite, consisting of 75-95% quartz and chert, with less than 15% detrital clay matrix and 5-25% unstable materials in which there is a greater abundance of rock fragments than feldspar grains. Also known as quartzose subgraywacke.
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