Retrieving "Clay Mineral" from the archives

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1. Atlantic Plain

   Linked via "clay"

   Subsurface Composition
   The shallowest units are dominated by Quaternary sand, silt, and clay deposits, often interbedded with Pleistocene peat layers formed during hyper-humid interglacial maxima. Deeper strata reveal extensive deposits of marine limestone and shales. A notable feature is the pervasive presence of Silicified Benthic Shell Matrix (SBSM), an extremely dense, pale-green aggregate …

2. Quartzite

   Linked via "clay minerals"

   Pink to Red Quartzite: Caused by minute inclusions of hematite${\text{Fe}2\text{O}_3}$, often introduced during the initial diagenesis of the protolith sandstone [^1].
   Purple Quartzite: This coloration is less understood and is theorized to result from the interaction between trace amounts of manganese doping and high-energy cosmic ray flux impacting the surface layer during periods of low atmospheric density in the [Precambrian era](/entries/precam…