6. The Gold is found in positions where there is a transition from the ordinary crystalline rocks to those of the sedimentary character. This remark leads us at once to the interesting and debated subject of the “Origin of Gold.” Some say that the gold of our gullies and hills is washed down from a matrix or source,—that is from certain golden lodes in a mountain. Others affirm that a volcano once burst forth and showered gold instead of cinders, and they direct us to the shot like appearance of nuggets. It is believed, also, that mica is the mother of Gold. Without doubt some is washed down by rivers, and more was deposited by ancient floods when covering the whole country, but a large amount is found in situ as it always had been. It is assuredly a fact noticed in all auriferous countries, that the gold is seen in positions where the sedimentary looking rocks come in contact with the so called igneous rocks. It is also, always found associated with iron, and commonly in the decomposition of rocks. It is in auriferous sulphuret of iron in Chili; ochreous decomposed silicious rock, adhering to specular iron, in Columbia; ferruginous sands in the Niger; decomposed reddish granite in Thibet; honeycomb quartz and rotten slate in Virginia; black peroxide of iron in Ceylon; pyrites in decomposed felspar in Hungary; sulphuret of iron in quartz in France; ferruginous clay slate in Granada; with iron of all kinds in Wieklow; decomposed crystalline rock with iron pyrites in the Ural; so in California, so in Australia. It would appear, then, that the gold was the produce of certain changes in certain rocks. The formation of crystals is somewhat analogous. The wall of a mine previously bare is seen gradually to get covered with crystals. Even crystals of iron pyrites are so produced, and are known by miners as “Young Mundic.” There must be, then, constant activity going on in the apparently inert mass of mineral matter. There is no rest in creation. The heavens above us speak of eternal movement. The animal and vegetable kingdoms reveal an incessant round of change. And now the dull rock unfolds to us the existence of motions and transformations that know no stay. There may be death upon the earth, there can be none beneath. We sweep off crystals only to make way for more. And may it not be so with metals in general? We may not know the particular elements and circumstances necessary for the formation of the yellow treasure, but some approximate conception may be gained by observation.
If crystals are the flowers of the earth beneath, metals are unquestionably mineral trees in gradual development, and dependent upon certain acids, alkalies, and other materials, for sources of their transformations. Moisture seems essential for these chemical changes. The production of gold is observed to take place chiefly towards the surface, though at a considerable depth in the compact rock very minute particles may be detected. When the crystalline rock disintegrates, iron sand is developed and accumulated. Mr. Hopkins, of the Port Phillip Gold Company, the ablest practical mining geologist of the day, and who calls clay slate “oxidated crust of granite,” observes, that it is “within the limits of this transition of the crystalline base into the oxydated compound that the minerals become principally developed in veins, &c.” An interesting illustration of this is afforded at Specimen Hill, Bendigo, where the metal lies between the quartz and the slate. Again, at Clunes, the fissures in the quartz are filled with greasy red earth, highly impregnated with iron, and in this was the gold. Sir T. L. Mitchell, in his most interesting report, tells us, that the gold of Summerhill Creek was “in incrementitious portions and separate increments of quartzose crystals.” In fact, the metal is often detected in considerable masses in the solid rock apart from any veins, which could not be, unless formed in the very place. It is not often, however, that a lump of 106lbs, as at Louisa Creek, is found thus detached.
Our Gold deposits of Victoria, then, are not the products of washings from distant rocks, but of certain friable metalliferous rocks, which gradually wearing away unfold their treasures; and the gold itself is a sort of crystallization or growth in ferruginous crystalline formations, acting under regular, though at present unknown laws. Our rocks are at this moment producing gold. The metal is found on the tops of hills and in all possible situations. We never are sure where to drop on it. All we see is that where it is, there it is. In some gullies the sides of the hills are not favorable; in others they are. Long Gully, Bendigo, received a return of visitors, after being wrought out, to have the hills ransacked. Then, with regard to the Pipe clay, the gold is in it, on it, or under it, according to the locality; that is, according to the period when the metal was formed, and rolled off from the parent rock, whether before, or after, or during the development of the decomposed felspar. Some men who came down to pipe clay in a certain gully found no gold, and retired. Another party pierced through the white floor, and brought up the wealth. In Californian gully more than six feet of it contained gold. The pipe clay varies much in depth, from an inch to forty feet. Occasionally, as in the shallow, lucky, holes of Peg Leg Gully, there is no pipe clay at all. The character of the gold changes according to the locality in which the transmuting agency has been more or less active. The lumps, however, are not larger in proportion to proximity to some matrix, as supposed, or when nearer to the volcano, which others think threw out the lovely, weighty, cinders. Notwithstanding all this uncertainty which exists as to the whereabouts of gold, I believe that with the progress of science it will be quite possible at once to know the precise place in which to discover the hidden beauties. O the delicious yellow crystals! Who does not love to view them, whether in the form of fibres, scales, or nuggets! The poet well may sing;
Or 'midst the darksome wonders
Which earth’s vast caves conceal,
Where subterranean thunders
The miner’s path reveal;
Where bright in matchless lustre,
The lithal flowers (crystals) unfold,
And 'midst the beauteous cluster,