* 

 ECONOMIC SUMMARY. 21 



Brecciated quartz. This form is not abundant. It consists simply 

 of angular fragments of quartz in a siliceous, sometimes slightly felspathic 

 matrix. 



Hornsfone. In the commonest form this is simply a compact 

 siliceous rock not exhibiting any trace of subsidiaiy structure, as for 

 example, in the faulfc-rock close to the temple at Ramgurh ghat. Some- 

 times by the addition of felspar, this rock becomes a pegmatite, and 

 in one locality near Ticahara it gradually changes into a^ranite. 



Within the area of the coal-field only one trap dyke is exposed. 

 It crosses the Damoodah north-east of Burobins: ; 



Dykes. _ ^ ^ ' 



it is a good deal decomposed and has an earthy 

 appearance similar to that of many of those seen in the Raniganj field. 



In the neighbourhood of the field there are several greenstone dykes, 



as indicated upon the map : they are of no srreat 

 Greenstone. _ r xr j & 



importance as the longest of them can only be 

 traced for a few hundred feet. 



One remarkably compact basalt dyke occurs in the Hurdgudha 



nuddee east of Gopo: it is only traceable for a 



Basalt. ^ "^ 



few yards. 



Near the village of Gopo there is a small hill formed of trachyte. 

 The rock is composed almost entirely of felspar, and 



Trachyte. 



is in parts very vesicular, 



VI. — Economic Sum may. 



It will already have been gathered from what has gone before 

 that this field is of but small value in an economic point of view. 



The coal in the eastern part of the field occm-s generally in thick 



seams, some of them having low dips; but the 

 Coal in the east. 



quality is so variable, thin bands of coal frequently 



alternating with stony carbonaceous shale, that it is improbable that the 



( 129 ) 



