FiNLAYSON. — Geology of Quartz Veins of Otago Goldfields. 



77 



Vertical Distribution of Gold. — The present depth of workings has 

 disclosed an interesting variation in value from the No. 3 level winze 

 to the surface. The accompanying section shows the values at different 

 points, taking the average value through the whole cross-section of the 

 vein : — 



/Y.yy. 



dufls. 



to 



^3hcin 



16 \ntermediateLz\el 



1^ 



10 



20 



/v'o. /. Le\.'&i 



till? 



V ^( 





ISO' 



No. ^. Level 1 80' 



No. 3 Level ^40' 



k <' 



3 £. 





} Payable Ore.^ 



^'^/ » 



3otrreit Orz.- 



Fig. 5. — Cross-section of Barewood Vein. 



From the surface to a depth of 50 ft. the value rose from \ oz. to 1 oz. 

 per ton. From here to the intermediate level the value fell to 16 dwt., 

 and then more slowly, till at three stopes below No. 1 level it was 14 dwt. 

 From here to No. 2 level the mean value became very low — approximately, 

 5 dwt. Between Nos. 2 and 3 there was an equally rapid rise, and at No. 3 

 it varies from \ oz. to over 1 oz. per ton, while at the foot of the winze the 

 assay value is uniformly over 1 oz., and rich specimen-stone, particularly 

 the brecciated variety, may be picked up showing much coarse gold. It 

 is peculiar also that at this point the gold is often dark in colour and 

 rusty. 



At No. 3 level, below it, and for some distance above it, the gold is pretty 

 evenly distributed across the vein. Rising to No. 2 level, a barren block 

 of glassy quartz comes in, and the seamy gold-bearing quartz is pushed 

 over to the two walls, and divided by clay partings from the barren centre 

 block, which corresponds practically to a " horse " of country rock. This 

 block wedges out when followed in either direction along the strike, and 

 it also has an easterly pitch or dip along the strike of the vein. Both 

 these features may be seen on the accompanying plan of the workings. 



