The Mamu-Nkporo formation in the locality of Okigwe, Nigeria was studied by Akande and Mucke ( 1993 ), and they concluded that the carbonate discovered with associated chamosite was formed in a shallow marine subtidal to intertidal environment developed during periods of rise and fall in sea level.
22.
X-ray diffraction ( XRD ) indicates that the proportion of 7 ?B layers in bertherine-chamosite ranges from 5 to 28 %, and chemical analysis by scanning electron microscope-energy-dispersive X-ray spectroscopy ( SEM-EDS ) indicates positive correlation between % B and Fe / ( Fe + Mg ) ( Ryan and Hillier, 2002 ).
