20 HAYDEN AND HATCH: GOLD-FIELDS OF WAIN AD. 



(p. 13) it would seem that, previous to the formation of the auriferous 

 reefs, the gneiss was subjected to great pressure, which gave rise to 

 a series of parallel fissures, running obliquely to the direction of folia- 

 tion of the country-rock and probably more or less parallel to the 

 direction of pressure. In these fissures the vein material was 

 deposited. 



The walls of the lodes are frequently formed of an indeterminate 

 mass of fragments of talcose schist, brecciated, 



" Casing." 



quartz and much limonite : this selvage or 

 ''casing," which, however, is not always present, varies in thick- 

 ness from an inch or so to about one foot and frequently contains 

 small quantities of free gold. Not infrequently this casing is absent, 

 and the lode abuts directly on the country-rock : this is especially 

 the case where the latter is fairly hard, as in the hornblendic rocks 

 of Hadiabetta. 



The reefs, which are massive, are composed of hard, translucent 



Character and contents and crystalline quartz, usually white and barren- 

 of the reefs, looking on the outcrop (PI. 1), but at times 



stained with films of ferruginous material ; they contain also subordi- 

 nate quantities of other minerals including pyrite, marcasite, arseni- 

 cal pyrites, limonite, haematite, gold, silver, chlorite, talc, calcite, and 

 in places pyrolusite. The pyrites, which is the chief source of the 

 gold, occurs sometimes in bands in the quartz, sometimes in small 

 patches or even as small isolated crystals : the total amount of 

 pyrites as compared with that of the quartz is exceedingly small, and 

 its distribution appears to be quite irregular. Limonite is very 

 common as a product of decomposition of the pyrites. The gold occurs 

 chiefly in the pyrites, but small specks of free gold are occasionally 

 found in the quartz, where it is stained by thin ferruginous films, and 

 in the nondescript talcose material forming the selvage or casing 

 this latter material indeed was apparently also the chief source from 

 which the native miners, who worked before and during the last 

 century, obtained their gold, and many of the tunnels still remaining 

 ( 20 ) 



