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contained in it, will, as has been suggested, probably remain forever unknown to us, for these metals have been originally derived from depths which can never be subjected to our examination. It is not necessary in this work to go into a more detailed discussion of the source of these metalliferous waters, or as to the manner in which they derived the metals which they subsequently deposited.

The author is, however, ready to admit, and anxious not to neglect to state, that owing to certain more or less well-known causes the upper or superficial portions of many veins and other deposits of nearly all metalliferous ores frequently show, and often to a remarkable extent, evidence of what is known as superficial enrichment. This, as has been thoroughly explained in the case of iron ore, simply means the concentration or the enrichment of the ore in the upper portions of a deposit which have been exposed to the chemical (oxidizing) influence of the atmosphere and of surface waters. This enrichment of the superficial portions of an ore deposit has taken place more frequently, and is more generally applicable than is supposed. That many mines of the world are shallow, the ore ceasing to maintain its value as the vein is followed downward below the depths to which the oxidizing agencies have been in operation, is largely due to this fact. It is simply, like the placers, another case of nature's

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Diagrams illustrating Occurrence and General Character of Fissure Veins; the last is illustrative of Superficial Enrichment (Phillips, Dana, Le Conte).

accidental concentration of riches which is taken advantage of by man.1

It does not always follow that the hot waters which originally brought up the mineral matter have come up through some more or less straight break or crack, but it often happens that they have gradually worked their way up from the depths from which they derived their mineral solutions, through any cracks or breaks, great or small, which they could find, and at the same time, by acting very irregularly, and by dissolving out isolated and frequently disconnected portions of the rock, through which they passed, have deposited their load of mineral matter in these places, or at such other places where the conditions for deposition were favorable. The result of this is that we often have extremely irregular and disconnected deposits, or what are known as pockets, nests, or bunches of ore. These occur most frequently in a rock which in itself is easily soluble, chief among which, as is well known, is limestone. In this connection one has only to remember that most of the caves of the world are in limestone strata, and that these great caverns have certainly been eaten out or dissolved out by the slowly acting agency of water, hot or cold, through countless ages. Some eruptive rocks, however, also readily admit of this process of replacement or substitution. Hot waters would of course dissolve such a rock more readily than cold waters, owing to the action of which many caves are supposed to have had their origin.

These irregular deposits will be described at length in their proper place, but the importance of having clearly in mind the distinction between them and the more regular veins or lodes cannot be overestimated, because few things have given rise to so much. litigation in the United States as the physical and geological

1 It has been ingeniously suggested by Professor R. A. F. Penrose, Jr., that in many instances there has not been the great amount of erosion that is commonly supposed to have taken place since the fill ing of the vein or other kindred deposit with the valuable mineral matter which it contains. He has further suggested that if this is true, it is easy to understand why there should be a greater deposition of certain mineral solutions nearer the surface than at great depths, simply because of the fact that the hot waters containing

them would be under less pressure nearer the surface than at great depths, and would be apt to deposit the solutions which they contain as they approach the surface owing to the relief of pressure. This is a very able explanation, and one which probably contains much truth. The subject, however, is a very vexed one, and but little is known concerning it. The conditions surrounding deposits in different localities are so widely different that it is impossible to lay down any general rule.

nature of a given ore deposit. It makes a great difference whether or not it should be regarded in the eye of the law as a vein or lode deposit, and made to possess all the legal attributes of such a deposit, or whether it should be regarded as one of a more uncertain, pockety, discontinuous, and disconnected nature, which, like a quarry of building stone, is properly located only as a placer deposit when upon lands belonging to the government.

The difference between the following classes of deposits are clearly defined, and are easily appreciated by any one who is not only scientifically familiar with the subject, but who has also had wide experience in many different kinds of mineral deposits. That the testimony of a man of no scientific knowledge, and whose experience has been limited perhaps to a single mining camp, should be taken upon a subject involving such important interests is preposterous, although it is just such testimony as this, followed up by a lack of knowledge on the part of lawyers and judges concerning the fundamental differences between these classes of metalliferous deposits, which has given rise to so much confusion in our mining law. For the reason that a large proportion of the mining litigation in our Western States, especially with regard to gold and silver deposits, has been directly or indirectly based upon the differences between the following kinds of deposits, and that the question of the proper classification of a given valuable deposit is certain to be frequently raised again, the different characteristics of ore bodies will be described in the following pages at considerable length.

While the deposits worked for the extraction of these two metals, gold and silver, have been, and will continue to be, most important in mining, as well as in a legal sense of those which are worked in this country, especially in the portion of it west of the Mississippi River, it must be remembered that the kind of metal or "other valuable mineral substance" which the deposit contains has nothing whatever to do with the geological or legal distinctions which will be made. For instance, exactly the same remarks as have been made with regard to gold and silver deposits would apply to deposits of antimony, arsenic, bismuth, cobalt, copper, in some cases iron and manganese, lead, quicksilver (mercury), nickel, tungsten, and zinc. In a word, it is always the geological peculiarities of a given deposit, and not the character of the ore contained in it, which determines the nature of the legal reasoning which should properly be applied to it.

7

A. UNSTRATIFIED MINERAL DEPOSITS WHICH ARE Regular.

(a.) Fissure Veins and True Lodes.

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Generally speaking, these are better known as Vein deposits, or frequently as Lode deposits. They must not be thought to be always a vertical crack, filled with mineral matter, running for a great distance across the country, and uniformly rich throughout its entire lateral and vertical extension, for such veins are rare, and, practically speaking, are never met with. Fissure veins are sometimes vertical, but more frequently dip at varying angles. They are thick at places, and at other places very thin, and frequently seem to disappear entirely, -nothing but a mere crack indicating their continuity, to reappear again in the same line. They usually are more or less straight, but are frequently crooked. They are often broken and faulted, so that it is often difficult to recognize and state positively that the different portions belong to the same or the original vein. In fact, the breaking and the subsequent separation of parts of a fissure vein have given rise to some very interesting legal questions. Generally speaking, if one can positively identify the broken and detached portions of the vein beneath the surface, the owner of the upper portion, or that which outcrops, has a right to follow the portion of the vein which has been broken off, and removed some distance from the one which he has been working, provided the break has not removed it to an unconscionable distance. Of course, if faulting should make the vein have two outcrops, it would be unreasonable to give the owner of the highest outcrop the right to follow that portion of the vein which outcropped on the claim of his neighbor. (See explanatory diagram:) This is, however, a most unusual occurrence, and it is usually just as easy to identify portions of a vein as belonging to one original and continuous vein, as it is to identify and place together the different pieces of the so-called "glass snake" after it has been disjointed. If, on the other hand, there are several veins of much the same size, etc., in close proximity, and of much the same character, it rarely becomes difficult to identify the separated portions in it. Very fortunately, however, no two veins are exactly alike, and they usually present such different characteristics that their separated portions can be very easily identified. Moreover, it is unusual that there are two large or valuable veins in very close proximity to each other.

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Dimensions or Thickness. The size of a true fissure vein may vary from a fraction of an inch to in some cases as much as several hundred feet. The latter great deposits are often, though not always, more in the nature of contact deposits than true fissure veins. These contact deposits will be described in the next division. The usual size of veins, which are commonly worked for the valuable metals which they contain, vary from a few inches to forty or fifty feet; but it may be said that, generally speaking, they are less than twenty feet in width. They seldom maintain their thickness for any great distance, but are apt to get thinner and thicker as they are followed along their course, giving rise in some cases to roughly lenticular-shaped bodies of ore.

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Quality and Character of Contents. - Veins vary much in the quality and richness of their contents, and it often occurs that a number of metals are found more or less mixed together as they were deposited in the same vein; such as gold, copper, silver, iron, manganese, lead, zinc, antimony, bismuth, etc., most of which are usually combined with sulphur, at least in that portion of the vein which has not been subjected to surface influences which have caused this element to be totally or partially eliminated. It is only when one of these metals predominates, not in

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