Lecture by Mr J.A. Pond.

Thames Star, Volume XIV, Issue 4588, 18 September 1883, Page 2

Lecture by Mr J.A. Pond.

Mr J. A. Pond's promised lecture on " The formation of our gold bearing lodes " was delivered in the Academy of Music last night to a crowded audience. ,Mr T. L. Murray, President of the Mutual Improvement Association, under whose auspices the lecture was given, presided. Owing to Mr Pond suffering from a severe cold, Mr Home, Secretary to the Association, read the lecture, which began by giving a short sketch of the important part metals had played in the history of the world from the earliest ages, the demand for them growing as theknowledge of their valuable properties I became more widely known, and the progress of civilization gave the human race better facilities for obtaining and treating them. In the earlier days of mining only the rich parts of tho deposits were worked, but as knowledge increased the miner extended his operations, and having improved tools and better* methods of treating the various ores at his command, was able to successfully mine the poorer portions of the lodes./ The lecturer then proceeded to show how the fissures in rocks, both primitive and sedimentary, had been formed, first by upheavals tilting the sedimentary rocks more or less on edge, and then by the cooling and contracting of the primary rocks cracking overlying ones. These fissures had been, in course of time, filled by the settling 01 matter held in solution in water, and had thus become reefs. Several lantern views were shown illustrating the manner in which the fissures were formed, and also showing sections of lodes in Cornwall and Cardigan, the rules applying to which would in a large measure serve for this field. The reefs there did not have regular walls, but in places, owing to the hangingwall having slipped, were small, while in others, when lying in more favorable country, the lode was larger and much richer. Reefs were not always formed at one time, but in places two or three layers of quartz, formed at long intervals, were met with in the same reef, and at the Thames he had seen as many as five separate formations. As was the case here, the lodes dipped much straighter than the underlie of the strata of the surrounding country, and thus though a reef might be rich in one place, where in favorable ground, in another, lower down, while passing through a barren strata, it would be worthless. The lecturer then referred to the Thames district in particular, quoting largely from a report on the goldfields of the Coromandel, Peninsula, furnished by Mr Cox to the Geological Department of New Zealand. A plan prepared by that gentleman, and showing the dip of the strata from the Earaka Creek to the Kuranui Bill, was explained, and the lecturer stated that the formation outcropping at the Karaka Creek was met with first at the No. 8 level of the Queen of Beauty shaft, and as the company got j their richest gold below chat level, and the strata was dipping towards the northern end of the field, he did not think they need have any fear as to the payableness of the deep levels. 1 Lantern slides illustrating the position of hard bars in the Waiotahi and other mines were also shown, and the lecturer impressed upon the audience the necessity of so mining as to avoid these bars, or only cutting through them at ] right angles when it was necessary. By this means much labor and expense would be saved. He then passed on to explain the manner in which the gold and other minerals had been deposited in the fissures. Silica, which was one of the chief components of quartz, was soluble in water at a great pressure, and gold and other metals and minerals were also capable of being held in-solution under certain conditions. The fissures referred to would be filled with these solutions, and the various acids coming into contact would have the effect of causing the metals, &c, in solution to settle and form a solid substance. This settling would take place in a greater degree where the water was not much disturbed, thus accounting for the unequal distribution of the metals. The effect of the mingling of different acids was shown by a number of experiments made by Mr Pond on the stage, and it greatly assisted the audience to comprehend the process of the deposition of the minerals in Nature's laboratory. In conclusion the lecturer urged the Thames people, though it was late in the day for such a step to be taken, to form a- Mining Institute here, stating that if he could be of any use in forwarding such a project, he was entirely at their service. A vote of thanks, moved by Mr Adams, and seconded by Mr. Bagnall, was carried by acclamation, after which Mr Pond returned thanks and the meeting dispersed. ;