Finlayson. — Scheelite of Otago. 



113 



class in Otago. The Macrae's goldfield occupies an area of 

 two hundred square miles between Dunback and the Taieri 

 River, and extending from the Mareburn in the north to the 

 Stoneburn in the south. 



The country rock is an argillaceous mica-schist, with much 

 interfoliated quartz. With few exceptions, it has throughout 

 the area a uniform strike — north-west and south-east — and a 

 north-easterly dip of from 10° to 20°. The veins consequently 

 all have that dip, allowance being made for local irregularities. 



A description of the features to be seen in Messrs. W. and G. 

 Donaldson's mines will sufficiently illustrate the characters of 

 the veins. 



Donaldson's Reef, Mount Highlay. 



This outcrops 10 chains up the hill to the west of a small 

 creek running north to the Mareburn. The hanging-wall is very 

 ill denned, and for a distance of 40 ft. beyond the wall the country 

 rock is impregnated with pyrite, and crossed by frequent slides. 

 Near the hanging-wall a few lenticular bunches of segregated 

 quartz appear. 



The vein, near its outcrop, is cut by a north-south fault, 

 which has dragged it down in a very striking manner, and open- 

 cast work along the fault-line displays a good section (fig. 7). 

 Both walls are here smooth and slickensided, as a result of the 

 faulting, and the hanging-wall country is much twisted and 

 broken. 



Fig. 7. — Section across Donaldson's Lode, at Fault-line. 



Followed west up the flank of the hill, the foot- wall continues 

 well defined, with a varying seam of quartz, but the hanging - 

 wall loses its individuality, the lode-material grading off into 

 crushed and veined country rock. 



The reef carries from 10 dwt. to 15 dwt. of gold per ton, 

 and scheelite in places. 



Golden Point Reef. 



This outcrops on the right bank of the Deep Dell, directly 

 south of Mount Highlay. It has a mean north-easterly dip 



