MOUNT RANGITOTO SILVER MINE.

Globe, Volume V, Issue 579, 27 April 1876, Page 4

MOUNT RANGITOTO SILVER MINE.

In consequence of the great number of applications received for shares from all parts of New Zealand, the directors have decided to issue the shares according to the prospectus advertised on Saturday, and we hear that 403 shares have already been applied for in this city. The West Coast Times of the 241 h has the following remarks on this subject- “ At a time such as this, when the developement of the mineral resources of the province has made some progress, and a company is being floated to work the argentiferous galena of Mount Rangitoto, it may not be unprofitable to weigh the evidence for and against the issues therein involved. Ihe first portion of the subject must necessarily be the various assays of the quality of the ore found, from which we will first take Mr Kirkland’s, whom a large experience and much careful study have qualified to a higher extent than any other person in a similar capacity in Australia to form reliable judgment. He finds, out of the three lots tested, that No. I concontains 735 ounces, and No. 2 392 ounces of silver to the ton, and that No 3 is not argentiferous to an appreciable degree. Then we have Mr Skey, the Wellington Government assayer, who tests two samples, or which No 1 gives six ounces three and a half pennyweights of silver to the ton of rough ore, or forty-three ounces to the ton of galena, and No 2 nearly eight ounces to the ton, and a consequently higher average to the galena. The third analysis is made by Mr Lewis, who obtains from a small specimen of 4( 0 grains a yield equal to 19oz lldwts 21gr of silver to the ton of rough ore. Added to these three, there have been several unofficial amateur assays, with varying results, the only noteworthy one being by an eminent pharmaceutist of this ilk, who was unable to discover any trace of silver in the ore or elsewhere, But these crude efforts may at once be passed by as valueless, as without previous training and much study, the extraction of silver from its gangues is neither easy nor profitable. Having these assays before us, we will now turn to other parts of the world, and see what is considered payable ore there. In Mexico silver ores are generally div ded into three classes, according to their yields—a fi r st class ore giving 110 ounces, a second class ore giving fifty ounces, and a third class thirty ounces to the ton, below which, with the usually rude machinery and many drawbacks to which mining is liable in that country, it is not remunerative. The average yield of the Mexican mines is about fifty ounces to the ton. In the State of Nevada, where the ore has been exceptionally rich in the Comstock and Gould and Curry lodes, a slightly higher average is obtained. In Germany some mines yield as low as twenty ounces to the ton, and still show a margin of profit. Recurring again to the assays of the three experts we have named, we cannot but giro the highest position to that of Mr Kirkland, whom, combining the highest training and the most ma'ur. d experience, with the delicacy of manipulation for which he is so greatly distinguished, had to aid him the advantages of a laboratory without rival in the colonies, while those of Messrs Skey and Lewis cannot but be deemed to a certain extent empirical and perfunctory, especially in the latter case, where the appliances have been so recently extemporised, and the previous practice of the operator of so limited a nature. The galena having been first found, and then assayed, aud the comparative value of the essays glanced at, we will now take a look at the ore in situ, and see whether the conditions nr-der which it lies are favourable or otherwise, and of such a nature as to give good grounds for supposing that the deposits of ore are likely to be extensive, and here also we must admit all the uccessa'y things are present. Dioritic porphyry encloses all the richest ores in the worl and this rock largely abounds in the Mangitoto ranges. It may therefore be deduced that if holders of mineral leases will energetically prospect their areas, good results will follow, and they may at the same time bear in mind that a high per centage of lead, even if combined with only three or four ounces to the ton of silver, can be worked to pay by using Pattinson’s desilverising process, which is alike remarkable for its simplicity and economy.”