GEOLOGICAL OCCURRENCE. 



41 



Talc-schist and compact potstone. 



Chlorite-schist. 



Limestone and dolomite with chondrodite, wollastonite and 



tourmaline. 

 Ophicalcite and ophidolomite. 

 As an example of a section across a typical schist " country " 

 containing pegmatites the accompanying section near the well-known 

 mica centre, Koderma, may be given as one readily accessible for 

 examination. 



The two hills, Mowatand to the south-west and Banda to the north- 

 east (fig. 13), are composed of a biotite-hornblende granite which is 



Mowatand 



1853 

 Banda H.S. 



Fig. 13. Section through the schists north-west of Koderma, Hazdribdgh 

 district. Scale 2 in. = 1 mile. 



foliated in conformity with the schists between. Near its junction 



with the schists there is generally a zone (a) of variable composition! 



apparently the result of contact action. Below this there is a zone 



of hornblende-gneiss (0) with garnetiferous felspathic bands ; then 



comes mica-schist (c) including a band with large garnets, followed by 



hornblende-gneiss [d), and another band of mica-schist (e), in which 



pegmatite-lenses are common. Occasionally bands show biotite 



flakes an inch across and garnets as large as a fist. The next band 



(/) contains fibrolite, followed by a zone containing silvery mica and 



garnets, lying on mica-gneiss with fibrolitic bands and pegmatite 



sheets parallel to the folia. The schist bands are often only an inch 



or two thick and some contain lumps of magnetite ; next occurs coarse 



biotite-gneiss with pegmatite. Then follows a thin bed of quartzite {g)> 



( 3' ) 



