Bangladesh comprises of 30 AEZs (Agro Ecological Zones) where mineralogical composition is an important controlling factor of soil fertility. However, such mineralogical information of soils of Bangladesh is very much insufficient and sparse. To address the situation, an initiative was taken to reveal the mineral content of important soils of different AEZs of the country. A part of such initiative, the mineralogy of five soil series from AEZ 22 (Northern and Eastern Piedmont Plains) and twelve soil series from AEZ 23 (Chittagong Coastal Plains) has been included in this manuscript. In AEZ 22, the average content of <2 μm sized clay fraction in soil was 20.4 while the 2-20 μm and 20-53
μm fractions was 32.3 and 34.6%, respectively. On the other hand, in AEZ 23, the average content of those clay fractions in soil was 32.5, 47.8 and 9.3%, respectively. Mica was found as the most prevalent among the minerals identified and it varied as 21-45 and 46-66% in AEZs 22 and 23, respectively. Next to mica, kaolinite, chlorite and quartz were present in considerable amount in both the AEZs. Intergraded vermiculite-chlorite minerals were found in some soils of AEZ 22 (Eastern part) while evidence of degradation of chlorite component was observed in AEZ 23. Such mineralogical observation of these AEZs is more or less conforming to the proposed mica-kaolinite-vermiculite* suite.