368 



mines ; but it is well established that the quartz conthrues to be auriferous 

 after it is traced into the harder undeconrposed rock. 



The gold contains the proportion of silver which is characteristic of the 

 compound of gold and silver known as Electrum, and is associated with native 

 Arsenic, Sulphides of Copper, Lead, Zinc, Antimony, and other metals, but 

 only in small quantities. 



At Coromandel, where mines were first worked in this formation, the 

 lodes have been " proved " to a depth of over 300 feet from the surface, but 

 the best mines at the Thames have, as yet, principally been confined to the 

 decomposed, and comparatively superficial rock. Veins have been discovered 

 and gold obtained at all levels on the ranges, from the sea level to an altitude 

 of 2000 feet. The quantity of gold that has been obtained from some of these 

 quartz reefs is very great, and for considerable distances the quartz has yielded, 

 pretty uniformly, at the rate of 600 oz. per ton. Such reefs are, however, very 

 exceptional. The quartz reefs are not altogether confined to the fine-grained 

 tufa rock, but when in other formations they are not so auriferous. Those in 

 the underlying slate I'ocks however contain decidedly more gold than the reefs 

 in the overlying Tertiary tufa, which seldom yield appreciable quantities.* 



The amount obtained up to the present time (Dec, 1869) is 213,489 oz., 

 only a few hundred ounces of which have probably been obtained as alluvial 

 gold, the remainder having been extracted from the rock matrix by true 

 mining processes. 



The development of this mining district must be looked on as hardly 

 commenced, though unless new districts be discovered, the large yield in pro- 

 poi'tion to the labour employed, which has hitherto characterised the early days 

 of the mines, cannot be expected to continue. 



Before proceeding to describe the second group of gold fields I may 

 mention shortly the character of the rock formation near Wellington, which is 

 the only other locality in the North Island where gold has been obtained in 

 appreciable quantities, though not as yet sufficient to entitle it to rank as a 

 gold field. 



The locality where the gold has been obtained is about twelve miles west 

 of the City of Wellington, near Cape Terawiti, where the country is composed 

 of abrupt ridges of Primary slates, shales, and sandstones ; with intervening 

 valleys, some of which are occupied by marine tertiary strata. The older 

 rocks belong to two distinct periods, and though both are found generally in a 

 vertical position, the line of junction between them is well marked. The 

 district has been traversed by a seiues of dislocations, which cross the lines of 

 stratification in oblique lines. The consequent displacement appears to have 

 indurated the sandstones, and altered the shales, when in contact with them, 

 into friable cherty slates of a deep blue colour, traversed by thread-like veins 

 of quartz. The altered sandstone is slightly micaceous, and has been so infil- 

 trated with silica, that hand specimens have been mistaken for granite. 



Near these altered patches of rock, a small quantity of fine-grained but 

 rough unworn gold is generally found, the total quantity obtained having been 

 about eighty ounces. Well-defined reefs of quartz also occur in the district, 

 especially in the sandstones, but none of these have yet proved auriferous, 

 on being tested, and the evidence seems to indicate the veins in the blue cherty 

 slate, as the probable source of the gold. 



Nelson and Westland, or Western Gold Fields. 



In this district, which extends along the west coast of the South Island, 

 for the northern half of its extent, the gold fields ai'e situated on the western 



* For full particulars respecting these mines, see Report by Captain Hutton, 

 "Geological Survey of New Zealand," 1869. 



