74 Transactions. 



The Vem-fiUing. — The quartz shows throughout a distinct banding, 

 parallel to the vein-walls. The crystal-axes of the quartz are distinctly 

 seen at right angles to the banding, and frequently very fine cavities with 

 comb -structure are to be seen (Plate II, la). Brecciation is common, the 

 quartz cementing fragments of country rock impregnated with pyrites, 

 and indicating that movement occurred subsequently to the first mineralisa- 

 tion of the fissures (Plate II, lb). 



Chemical tests and microscopic examination of the sulphides show that 

 the habit and association of the gold is very similar to that of the Carrick 

 Range. The quartz, according to Ulrich and to the statements of miners, 

 occurs in shoots dipping east along the strike of the veins. This is a matter 

 which cannot be investigated at present, as the old workings are all closed. 



The very high values which have been picked up near the grass on several 

 of the veins are evidently the result of prolonged secondary enrichment. 



Microscopically the ore is seen to be banded in alternate lines of coarse 

 and fine granules, and carries also bunches of fine granular quartz thickly 

 studded v.dth pyrite crystals (Plate II, 2.) 



Professor Park calls the Bendigo veins " immature replacement lodes,''* 

 but the highly drusy and crustified nature of the quartz frequently observed 

 argues rather for fissure-filling, and is a decided argument against Professor 

 Park's theory. 



The deepest workings in Otago were on this group, the Cromwell shaft 

 having been sunk to a depth of 500 ft. 



Other Veins allied to the Bendigo Veins. — The Conroy's Gully vein, near 

 Alexandra, is similar to these or to the Carrick veins. The group of small 

 east-and-west veins at Rough Ridge, now almost forgotten, are very similar 

 to the Bendigo type.f Lastly, the Nenthorn group, J east of the Taieri 

 Gorge, whose exploitation lasted for a period of two years, from 1889 to 1891 , 

 may be put under this heading. They comprise a similar set of narrow 

 parallel veins, striking east and west, and dipping either north or south at 

 a steep angle. 



(5.) Veins of Macrae's District. 



These are an important group of scheelite-veins, which I described in 

 a previous paper.§ They are typical bedded or segregated veins, being the 

 only group of this nature in Otago. 



(6.) Veins of Waipori and Southern Districts. 



Ulrich has described four of these veins — the O.P.Q., Canada, Gabriel's 

 Gully, and Saddle Hill veins. || He states that they are characterized by 

 shoots or blocks of quartz which " show an endlong dip in strike." The 

 feature, he says, " may be considered as an oblique banded structure on the 

 large scale," the banding being marked by alternate blocks of quartz 

 and mullock. He also remarks that the gold occurs in shoots in the quartz 

 blocks, in the centre or on either wall. 



The O.P.Q. {Otago Pioneer Quartz-mining Company's), or Shetland, Vein. — 

 This vein, near Waipori Township, strikes at about 160°, and dips eastward 

 at an angle of 56°. The country rock is a slaty quartz-schist, striking north- 



* Park, Bull. No. 5, N.Z.G.S., 1908, p. 63. 



t Ulrich, " Geology of Otago," 1875, p. 229. 



j McKay, Rep. N.Z. Geol. Explorations. 1890, p. 50. 



§rinlay.son, " Sclieelite-deposits of Otago," Trans. N.Z. List., 1907, p. 112. 



II Ulrich, " Geology of Otago," 1875, pp. 159, 191. 



