Farquharson. — The Platinum Graveh of Orepnki. 451 



A discussion of this point, with a probable explanation of the pecu- 

 liarity, arrived at by comparison of this area with the platinum-bearing 

 areas throughout the world, will be given when we come to investigate 

 the occurrence of the metal near Orepuki, in Otago. 



As far as Nelson is concerned, then, it appears that the metal is 

 found in what, as far as the evidence goes, must be regarded . as the 

 commonest method of occurrence — viz., in placer or detrital formations. 



As will be seen later on, in Russia the metal is got most abundantly 

 from the alluvium at the base of the Ural Mountains, alluvium which has 

 been produced exactly as the Nelson alluvium has been — i.e., through 

 denudation and the sorting-action of water. In Columbia, British Columbia, 

 Brazil, United States, Burm.ah, France, New Caledonia, and Tasmania the 

 mode of occurrence is exactly the same, so that, in all these countries, to 

 arrive at the original matrix of the mineral we must first trace back the 

 boulders and detritus to the parent rock. 



Of a nature almost exactly similar is the occurrence of platinum ih 

 Stewart Island. Sir James Hector, in the " Transactions of the New Zea- 

 land Institute " (vol. 2, pp. 185, 371), reports that small flat grains of a 

 steel-grey or silver-white colour have been found associated with the gold 

 in alluvial deposits in the island. Nothing further, however, is known 

 about this occurrence. 



We come now to the occurrences in Otago, of which there are two. The 

 less important of the two is that reported from the Gorge River, on the 

 west coast, near the celebrated Milford Sound, in Fiordland. This locality 

 is remarkable owing to the presence with the platinum of that peculiar 

 nickel-iron mineral awaruite. In appearance it is not unlike platinum^ 

 and was mistaken by the miners for that metal. An analysis of it runs as 

 follows : — 



Per Cent. 



Nickel ' . . . . 67-63 



Cobalt 

 Iron 

 Sulphur 

 Silica 



0-70 



3102 



0-22: 



0-42 



Both the metal and the awaruite occur in a district composed almost wholly 

 of serpentine and dunite. The awaruite has actually been found in the 

 serpentine. From this, therefore, it would appear, as Professor J. Kemp 

 points out, that the platinum and awaruite are excessively basic segregations 

 in basic igneous rocks, the dunite specially being ultra-basic. 



Occurrences of a similar nature, in which awaruite occurs with the 

 platinum, are reported from California, Oregon, and British Columbia. 



There still remains for consideration the second occurrence in Otago; 

 but, as most of our investigation deals with this occurrence, it will be suffi- 

 cient here to remark that platinum has been known in Otago for some 

 seventeen or eighteen years, but to such a small extent was its value recog- 

 nized, or so great was the ignorance of the miners who came into contact 

 with it, that it was not until about eight years ago that efforts were made 

 to collect or save it. Up to that time it had been almost contemptuously 

 thrown away. 



The first recorded occurrence was about the year 1888, when a miner 

 searching for gold found some ounces of it at the mouth of the Waiau 

 River. The occurrence created very little stir at the time, and the miner 



15' 



