MINERAL RESOURCES OF THE PROVINCE OF AUCKLAND.

Daily Southern Cross, Volume XV, Issue 1136, 18 May 1858, Page 3

MINERAL RESOURCES OF THE PROVINCE OF AUCKLAND.

To the Editor of the Southern Cross. Sir, — Permit me, through the Columns of your paper, to offer a few remarks and extracts upon raining and the mineral resources of this Province. It is more than likely that, at a peiiod not far distant, we shall derive the principal export and revenue ot-this Prounee from its mineral resources. This count, y has been compared to Gieat Britain : this analogy will, I think, bear more forcibly to our minerals than to anything else. It is well known that Britain owes her commercial and manufacturing greatness to her iron and coal ; and if we can judge from mineralogical indications, this country abounds in both, but the most promising of immediate advantages or profit are the gold and coppei mines. The general opinion is that all the goldmining districts are in the hands of the Natives : this is not the case, there are, at the present time, moie goldbearing quartz veins owned by white men than a number of the largest quartz mills could crush in twenty years. Those veins are conveniently located for mining operations ; many can be visibly traced by their outcroppings on the mountains until lost in Coromandel harbour. Fiom the extreme richness of many of those veins, and the present low rate of wages, it is evident that capital invested with care, and good management in crushing, those quaitz veins would makeasafe, speedy, and profitable return : the veins are comparatively soft and easily crushed, and but few of them would require roasting — which is an expensive process. They are designated or known as rose and cream-ooloured, which, in the gold mines, aie considered the best ; for two | reasons— they are easily crushed and contain a more | general diffusion of gold, which is extremely fine and ssldom visible. In the northern mines of California, up to 1852, quartz of this character was seldom found except in Nevada county, where, in one small valley, tlrero were 20 quartz mills continually crushing, and all

doing well ; men's wages varying from 5 to 10 tl jll>>rs per day, and the prices of all other things high in pi jportion. In ' Appleton's Dictionary of Mechanics' we find the following description of the minps ot the Southern States, together with a " Geological Description ot Gold and its localities" :—: — 11 In Virginia and North Carolina gold ore* are mined, crushed, and amalgamated, which yield but the 150,000 th part of gold to the bulk of ore, and these ores are worked with profit. The Russel Mining Co., in North Carolina, which operates 12 or more Chilian Mills, woiks ore which yields 10 cents of gold the bushel, or 100 lbs. ot ore, with profit. The Louisiana Mining Co., which employs stampers for crushing, shows that ores which yield 7 cents in the bushel, may be woiked and pay expenses and profit." With the exception of hovi (and possibly copper) it may safely be asserted that the geological districts within which gold occurs embrace a 1 lrger aggregate aiea than those of any other metal, and yet the proportion of gold to that "of the substances from which it must be separated for the use of mankind is so extremely minute that the cost of eliminating it must necessarily be such as to maintain a very high commercial value for this metal in all future times. Native gold occurs in veins which intersect hypogene or igneous as well as metamorphic rocks ; but the veins in the former have hitherto almost always proved too poor in metal to be worked with profit, unless in connection with other metals. Among the metamoTphic rocks, especially in talcose slates,, we find the auriferous veins most numerous as well as most pro luctive. And although the veins in porphyries, trap, and other hypogene rocks, usually are much less rich in metal than the slates, yet the veins in these are little productive, or do n t contain gold at all, where these rocks occupy extensive aieas without intiusive rocks forced up between or around them. These conclusions aTe sustained by the fact of this being the geological structure of all the districts in the world known to contain gold, under circumstances that permit it to be extensively availed of for the uses of mankind. The gold-bearing ve ; ns usually consist of quartz, of a texture so firm and hard as to require a large expenditure in mining it compared with the value of the metil obtained, moie especially when it is worked to considerable depths below the surface where atmospheric agents have not impaired the solidity and firmness of the vein stone. These, like all true veins Rre generally inclined at a considerable angle from the plane of t^ie horizon, and are often vertical or nearly so. In thickness they vary considerably ; the same vein is sometimes contracted to the width of an inch or less, whilst at others it is expanded in thickness to mnny yards. They extend downSvards to greater depths than the miner as ever has ever reached. The gold occuis sometimes disseminated throughout portions of the vein in minute scales, often so small as to beUnvisible to the naked eye ; then again it is found in scales, plates, or amorphous masses, vaiying in size from the smallest visible dimensions to those having considerable weight. These are sometimes irregularly distributed throughout the vein-stone, but most commonly extend within parts of the vein or upon its sides. Small crystals of gold also occur in the cavities of the vein-stone. pyrites usually accompany native gold, and somptimes also copper pyrites, both containin? some gold disseminated within them and not chemically combined. By far the greater proportion of gold hithprto has been procured from deposits of diluvium and alluvium in the volleys and ravines which have been formed in those regions where metallic veins existed prior to the formation of such valleys and ravines,. The gold in transported deposits (or drift as they may be termed) foimerly existed in those portion* of the ems destroyed by the operations of nature producing these denudations, and which often result in the formation of glens, ravines, and narrow valleys. This destruction and re-forrmtion are incessantly going on ; but during the present geological period with less energy than in the earlier era called the drift poiiod by geologists : now, as their carbonic acid and oxygon, aided by heat and water, are the chief agents by which the rocks and stony matters are disintegrated. The currents ot water m hilly and mountainous districts have usually considerable rates of descent, so as teadilv to float off the more fineTv divided portions in sand and mud as well as to remove the larger gravel and boulders. The only substances possessing specific gravities too great to be moved far from whence they were liberated are the heavier metals and some of their oxides. The weight of gold is such that it is rarely transported far from the veins. It is tiue, that in minute scales, or powder, part of it is carried off during floods by adhering to the passing sands, but it is rarely deposited in available quantities, except in close proximity to the veins in which it existed. Your most obedient servant, John MgLkod. Dundee Saw Mills, May 1 1th, 1858.