10 HATCH : THE KOLAR GOLD-FIELD. 



be explained later on, the quartz has the appearance of a subtrans- 

 lucent hornstone or flint with a well developed banded or laminated 

 structure. As a rule, gold is not visible in the hand-specimen, still 

 specimens containing " visible " gold are not infrequently found on 

 the picking floors. In such specimens the gold occurs in small 

 seams and is disclosed in scaly and granular aggregates on the two 

 faces produced by breaking the rock along such a seam. It is of a 

 rich yellow colour and of great purity, the average fineness of the 

 gold being about 920 parts in 1,000. Where slickensides have been 

 formed by differential movements in the vein, the gold sometimes 

 occurs as a fine film on the slickensided surface. 



Associated with the gold in the quartz are the following 

 minerals: — iron pyrites, magnetic pyrites (pyrrho.tite), 1 arsenical 

 pyrites [mispickel) blende, galena and copper pyrites (chalcopyrite) ; 

 but in the Champion lode the average amount of pyritic and other 

 heavy metallic minerals probably does not amount to more than one 

 quarter per cent. 2 Other minerals occurring in close connection 

 with the lode deposit are green hornblende [actinolite), the chief 

 constituent of the schistose "country rock"; pale-green pyroxene 

 sometimes occurring in bands in the quartz ; brown mica, usually 

 occurring in great abundance in the immediate neighbourhood of the 

 lode, and no doubt an alteration product of the hornblende effected 

 probably by the same agencies as gave rise to the vein formation ; 

 calcite, an alteration product occurring in small seams in the hanging 



1 Mr. Holland informs me that he found nickel in the specimen of pyrrhotite 

 I sent him from the Champion Reef Mine. 

 The chemical analysis was — 



Sulphur 40*05% 



Iron 5816 „ 



Nickel 1*84 „ 



100-05 „ 



2 A concentrate made by panning quartz from the Ooregum Mine contained a 

 mixture of pyrite minerals, amongst which were mispickel and a whitish metallic 

 mineral containing both cobalt and nickel. The concentrate on analysis yielded 

 about i| per cent, of mixed oxides of nickel and cobalt according to an analysis 

 made by Dr. Walker in the laboratory of the Geological Survey. 



