Leisure hours among the gems

by Augustus C. Hamlin

But where does this metal come from? the inquirer may ask. From a variety of sources, we may reply. Does not the water of the ocean contain it in appreciable quantities, and did not M. Sage extract it from the ashes of certain burned vegetable substances? We also know for a certainty that iron is produced by vegetable vitality, but we will not attempt to explain the manner or whence the material is primarily derived. Cosmic dust or the invisible atoms of the atmosphere may be the source. The origin of the gold nuggets and the particles of gold-dust in the well-defined placers, as advanced in the hypotheses of Raymond and Murray within the past few years, is connected very closely with the theory of the recent formation of diamonds in similar placers.

In connection with this theme, it is proper to make a digression in explanation of the condition and formation of the gold placers, as they seem to be highly suggestive of the depositions of the diamond placers. Gold is often found in the same strata with the diamonds, and the presence of the one sometimes indicates the deposition of the other. But this is not invariably the fact. Yet the peculiar formation in which the metal and the gem occur leads the geologist to similar trains of reasoning when seeking to explain their presence in the tertiary strata of very recent times. It has been generally supposed that all alluvial gold is the result of disintegration of the old crystalline rocks. But we now distinguish placer gold into two kinds, as the alluvial and that which results from decomposition of quartz reefs. The distinction between these two qualities of the same metal arises from differences which are quite strongly marked. The alluvial gold is generally much purer than the reef gold; and the reefs rarely, if ever, contain nuggets. The appearance of the nuggets and particles from the true placers, in comparison with the gold-dust evidently set free by aqueous action, is suggestive of a theory that they have been deposited by different agencies.

It has been suggested by Mr. Selwyn, the Government Geologist of Victoria, while studying these differences, that the gold nuggets found in the drift may have been deposited from solutions containing gold by means of electric and chemical agencies. Mr. Skey, analyst to the New Zealand Geological Survey, has recently come to similar conclusions from his researches on the subject. The theory is well illustrated by the formation of crystals and masses of iron pyrites from solutions of that metal; and as gold is often found associated, free and uncombined, in these pyritiferous depositions, there is sufficient evidence to believe there may be some connection in the manner of formation.

From the results of certain chemical experiments in the laboratory, it would appear that organic matter is one of the necessary chemical agents for the decomposition of some of the solutions of gold. Therefore, if we assume this hypothesis to have a positive bearing upon this question, the abundance of organic matter occurring in the gravel beds adds to its weight as an argument. Selwyn found in the gold-bearing drifts of Australia quantities of fragments of wood, roots of trees, and other organic débris to serve as nuclei, or as reagents for the reduction of mineral solutions. We may introduce as evidence the formation of iron pyrites in crystalline forms, which is taking place at the present day under the action of sea-water. The metal in these instances replaces the organic structure of wood, or assumes definite forms with a particle of organic matter as a nucleus.

The formation of gold nuggets from solutions of the metal is by no means as wonderful or difficult of explanation as some other phenomena witnessed in metallurgy. The strange play of pseudomorphism is well defined in some instances, if not well understood. Here we observe that the peculiarity of form may be rigidly adhered to, while the composition is completely changed. In the waters of certain copper mines, drills, rings, and bars of iron that have accidentally been left have in course of time become transformed into pure copper. The iron of the implements has changed places with the atoms of copper held in solution.

In connection with this interesting theory, there are some puzzling facts to be deduced from the phenomena of the auriferous sand beds of some of the rivers of Europe. The gold placers along the coast of the Danube and the Rhine are situated far from the mountains, the supposed sources of the metal, and there are also wide barren districts intervening. The river Tesino affords no gold in its sands until its waters have passed through and beyond Lake Maggiore. From these and other examples, it is quite evident that the gold which appears in these river beds has been derived from the placers through which the rivers have passed, and not from quartz reefs in the distant mountainous regions. The situation of these placers, with the evenness and regularity of their deposits, also the absence of auriferous ledges among the contiguous rocks, permit the observer to indulge in the idea that the gold may have been deposited from solutions and not from the decomposition of crystalline rocks. We certainly have sufficient evidence to object to that final explanation which ascribes all these depositions to aqueous action in distant times, and to the abrasion of primitive mountains, the evidence of whose existence is alone and doubtfully afforded by the débris which form the strata of the gold and diamond placers. The ancients long ago noticed the deposition of gold in the beds of rivers; hence the phrase “The gold-breeding sands of Pactolus.”

It has been a favorite theory with many persons of a philosophic turn of mind that all organic forms were created upon the earth not by mere chance or hap-hazard, nor by what have been called by the early geologists “freaks of nature,” but, on the contrary, with some definite intent on the part of the Creator, and perhaps for the welfare of mankind. Some of these far-sighted thinkers have advanced their views so far as to maintain that even obscure animal and vegetable forms may have some indirect or distant effect upon the well-being of man. We all must admit that it is indeed a beautiful hypothesis, even if it be contested by stern and savage arguments. But if we indulge in this manner of reasoning, there seems to be hardly a limit in natural philosophy in which we may not seek for evidence.

Can we not include the subject of our treatise among those things which are supposed to have some influence upon the moulding of human character? Certainly its geological age, its origin, the beauties and wonders of its physical properties, and their application to art and science as well as to the wants of society, furnish evidence to sustain an inference.

But how can a cold, inanimate object like a gem influence the condition or expansion of the human intellect? the rigid materialist may say. The gems, he will maintain, apply only to the superficial wants of man, and directly tend to degrade rather than elevate our natural morals; that they are articles of commerce, and that commerce debases our natural instincts.

On the contrary, we may say that the beautiful in nature of whatever degree is calculated to assist in the development of mental culture; and without these beautiful lessons and examples constantly spread out before us, man would always have remained in a state of utter barbarism. As we look back upon the history of life, how many of the triumphs of human architecture may be traced to the suggestions arising from the observance of the varied forms of nature! Nearly all of the beauties of the Gothic or Grecian styles may be found existing in the fossil relics of by-gone ages or even in the multiple forms of existing vegetation. What grand deductions Newton derived from his studies of the glories of the opal and the iridescent gleams of the soap-bubble!