PART 4.] 
95 
Ball: Copper of Dhalbhtnn and S'vnghbhuin. 
sub-metamorphic rocks are let-in by an east and west fault; thence southwards they pass 
into the district ot Singlibhum, where they eloke round irregular areas of metamorphic 
rocks. The principal oi these areas lies east ot tho station of Chaibassa. The rocks seen 
aie coarse granitic and porphyritic boss-forming gneisses which are traversed by a perfect 
network of trap (diorite) dykes.. This combination produces a very peculiar effect which, as 
seen from the top of a high hill, has been aptly compared to a chessboard. The walls 
formed oi trap dykes constitute substantial boundaries between adjoining properties. North 
and north-west of Chaibassa there is another area of the same metamorphic rocks which 
is, however, free from trap or nearly so. A third small area exists near Khursowa, regarding 
which something will be said again further on. The appearance of the sub-metamorphic 
area is very different from that just described ; it is characterised by being traversed by long 
ranges of lulls with deep intervening valleys which correspond to the position of the 
softer varieties of rock of which the formation is composed. 
The copper ores to which this account refers occur for the most part in a zone of schists 
whose geological position is situated near the base of the sub-metamorphic rocks. These 
schists form the northern flank of a broken spur of hills which leaving the Chota Nagpur 
plateau strikes eastwards for a distance of 40 miles through the estates of the rajahs of 
Khursowa, Seraikela, and Dhalbfium, then bending round gradually to south-east and ulti¬ 
mately to south, it disappears uiidt-r the alluvium of Midnapur. 
The principal ranges composing this spur are of quartzite, upon which incrustations of 
the copper salts are occasionally found ; but the ore which has been worked is, with a few 
exceptions to be noted hereafter, associated only with schists. 
Measured along the strike, these copper-hearing rocks extend for a distance little short 
ot 80 miles. Copper ores have not been discovered west of Lopso; hut there is no geological 
*® ason , w %, tl:| ey should not be found for many miles further in that direction in the Chota 
Nagpur highlands. 
In the tables appended an abstract is given of the principal facts which have been 
observed at the various localities in which the copper has been found. And in the accom- 
panymg map all these localities are indicated. M. Stoehr’s paper contains all the available 
reliable information regarding the working of the mines. 
The .determination of the question as to the manner in which the copper occurs, 
whether in lodes or as a deposit, is one of no less difficulty than it is of importance. M. 
Stcehr holds the opinion that, it occurs in lodes, though admitting that much may be said in 
iavor of the_ opposite view. He describes the variable strength of the deposit itself and 
the interruption and separation ot the outcrops which in some places are close to each other. 
• Carrying out this view, he distributes the localities where ore occurs along two lodes which 
he calls the north and south. He alludes to the fact of tho existence of particular beds of 
rock m the vicinity of the copper showing signs of excessive metamorphism which he 
considers to be due to local action; but he does not mention that the copper, if followed along 
itshneol strike, is found to penetrate into areas occupied by rocks which are undistiu- 
guishable m them lithological characters from the most crystalline rocks occurring in the 
older senes. Of course it may he that these, like the single beds above mentioned, have been 
affected by local metamorphism, possibly caused by the intrusion of granite, hut the granite 
which occurs is not distinguishable from that which is often found in Bengal to alternate with 
well foliated rocks, and is therefore believed to he of metamorphic origin. Thus this 
circumstance, which might otherwise be used as a crucial test of the validity of the lode 
hypothesis, is itself so uncertain and fraught with doubt that it is a rather dangerous 
description ol evidence to make use of in such a discussion. 
In support of the view that the copper partakes of the nature of a mechanical or chemi¬ 
cal deposit m the beds, there is the tact that the underlie of the ore as seen at the surface 
nearly always appears to correspond with the dip of the schists, and that sometimes the 
schists appear to be permeated throughout with the ore. Adopting this view for the moment 
the following supposition would appear to afford a possible explanation of most of the 
phenomena with regard to the ore, which have as yet been observed. With the original 
materials oi the sandstones and mudstone shales, which subsequently become metamorphosed 
into schists, the ore may have been either chemically or mechanically deposited At some 
period the crushing and tilling up of the rocks, of which there is abundant evidence 
produced cracks and possibly openings between adjacent beds, towards which a s,.ere-mHon 
oi the copper particles which until that time were equally disseminated throughout the”muss 
