Granite Rock of Maddhapara –a new Source of Pozzolana for Bangladesh


About 1.2 square kilometer underlain deposit of hard rock at Maddhapara of district Dinajpur, may be a versatile source of pozzolana in Bangladesh. At present, the mine is designed to produce boulders and aggregates from the underground reserve to meet the requirement of flood control, construction of coastal and town protection embankment, construction and maintenance of bridges, roads and highways, embankment, river training, railway ballast, high rise buildings, decoration tiles and other heavy duty construction works. The rock deposit is overlain by about 140m of unconsolidated sediments. Below this, the basement is the Archean era and subdivided into the kaolinized granodiorite, the weathered granodiorite and fresh granodiorite. Dykes of micro-granodiorite (Fig. 1), fine grained silicified whitish granite (Fig. 2) and pegmatite is thinly inserted in the basement. In the upper part of the basement, the granodiorite was highly weathered and thus is friable. The rock exhibits grey to greyish black colour, medium grained and is of granitic texture depending on its weathering level. Due to weathering effect, feldspar was decomposed and dark minerals (biotite, amphibole and pyroxene) lost their crystalline forms. Weathering on granodiorite appears to be lower with increasing depth and the rock is greyish black. 
 [Ref.: Report on Geological Survey of Boreholes/Chapter II, Page 10 and Records of Geological Survey of Bangladesh]

Fig. 1: Granodiorite rock along with quartz and mica.                 



Fig. 2: Granite rock along with quartz and feldspar


The micro-granodiorite is found through out the mine area. The rock occurs in the form of dyke, with a thickness ranging from 2m to 15m. The rock is composed of feldspar, quartz and dark minerals. It is black coloued due to a large amount of dark minerals contents. Minerals in the rock were tightly interlocked through silicification and thus, the rock is comparatively hard. Some micro-granodiorite looks very similar to the gneiss texture, since dark minerals in the rock are concentrated in a certain direction.

Fig. 3: Feldspar rock along with some quartz and mica

Considering the prevailing scope of limited utilization of Maddahpara hard rock, a study was carried out with an aim to introduce it as a new source of pozzolana which subsequently be used in cement manufacture in Bangladesh. .      

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