干旱区生态环境知识资源中心

The Kapurdi lignite deposit of the Barmer Basin is one of the important Tertiary lignite deposits underlying the Great Indian Thar desert in the northwestern part of Rajasthan. The sedimentary sequence of the area is characterised by marked lithofacies changes over short distances. The lignite beds in the sequence are lenticular in shape, dark brown and exhibit non-banded granular texture. The Vicker’s micro-hardness values (H-mu-V) vary in close range from 20.0 to 22.0 kg/mm2. Chemical analysis of the lignites has shown that they are low in ash and matured in rank, like the lignite deposits of the Palana Basin. The lignite ash contains low silica contents with appreciable quantities of alkali and other oxides. This has caused the lower ash fusion temperatures.

Petrographic studies have revealed that the huminite group of macerals is the dominant constituent in all the samples. Humocollinite is the major constituent in the lignite beds, while humodetrinite predominates in the carbonaceous beds. In the liptinite group, resinite is the major component. It is found as infillings of cavities, joints and cell lumens. Conspicuously, the inertinite (organic inert) content is very low and is mainly represented by fungal bodies of sclerotinite. The reflectance values of Kapurdi lignites further corroborate that they are matured in rank and may be grouped in the "hard brown coal" category.