33 SILVER MINING INDUSTRY IN CHILE. Translated from the Spanish, by Henry Swinglehurst, in April, 1860. HE territory of Chile may be divided into two regions, whose products, which are essentially distinct, are the base of the economic system of the Republic. The one situated at the south of the river Aconcagva is exclusively agricultural; the other which is composed of the provinces situated to the north of this river, essentially mineral. The agricultural products of Chile being for the most part cereals and cattle, their exportation is difficult and scarcely profitable, for which reason they only figure as a small portion in the statistics of exportation, whilst the metals, whose demand is incessant, make up the major sum in the value of her exported produce. The northern provinces, therefore, must be looked upon as the grand laboratory in which the products of Chile are transformed into exportable material. From this, it may be judged of what importance must be its mining industry, which is at the same time the most important consumer of her agricultural produce, and the source of her exportations. For such considerations it is of paramount interest to study the march of mining industry, to form an exact idea of its present situation and its future prospects, and also to investigate to what extent it may correspond to the necessities of the Republic. PRODUCTION OF SILVER. Situation of the Mines, and the Geological character of the All the silver mines of Chile are found to be included in a very narrow zone, running from the south to the north from C 34° to 26o 30', and thus occupy a length of nearly 200 leagues. This zone corresponds to an immensely extended fissure, which follows the western base of the Andes, and forming, in the provinces to the south, a depression known under the name of the Llano longitudinal (longitudinal plain). In every point situated on this break or fissure, the stratified rocks have been extensively modified, and present themselves in the state of metamorphic rocks, and manifest the action of incandescent materials issuing from the interior of the globe. In the particular case of which we treat, the trachytes and acids of sulphur are those materials which have played the most important part. The mineral deposits are not found equally distributed over the whole extension of this zone. They appear, more especially in the hills, in the points where the trachytic rocks issue, and as these are most abundant in the north, the deposits of silver ore are also more numerous near to the northern extremities, and especially in the province of Atacama. Santiago, i.e., the province of this name, only presents four mines, of but little importance:-those of San Pedro, Nolasco, and of the Cerro de San Lorenzo, situated near the town of San-José, that of the Condes east of the city of Santiago, and the Runque towards the extreme north of the province. That of Aconcagva, in which the trachytic rocks are very rare, contains only the mineral deposit of Catemu. The province of Coquimbo contains the mineral deposits of Arqueros, much more important than the foregoing, whilst that of Atacama contains those of Aqua-Amarga, Chuchampa, Rosilla, Chañarcillo, Sacramento, San Antonio, Cabeza-de-Vaca, Romero, Pampa-Larga, Ladrillos, Zapillar, Garin and Tres-Puntas, from which have been extracted almost all the silver exported from Chile. The silver mines, therefore, belong almost exclusively to the province of Atacama, and consist principally of veins or masses slightly inclined, crossed or traversed in every direction by small metallic veins known by the miners under the general term of mantos. The rocks, cut or crossed by the veins, vary in age and composition, according to their locality. At times they belong to the silurian formation, as may be seen at Tres-Puntas, where one of these veins is found in gneiss; also in the Devonian system, as at Zappallar, at the Romero and the Cabeza-de-Vaca; and even in the arsenical coloured rocks or the lias, as in San Antonio, Lomas-Bayas, Chañarcillo, and Aqua-Amarga. The composition of these distinct rocks appears to have had a great influence on the richness of the parts of the veins with which they come in contact. From a condition of perfect sterility when found in contact with certain rocks, the richness of the veins goes on rapidly increasing on approaching the strata of rocks of a composition distinct from the former ones; a circumstance which has led the miners of Chile to divide these strata in two classes-productive and barren-under the names of Panizo-pin-tador and Panizo-broceador. The nature of these metals varies also with the composition of the strata in which the vein is found. Thus chloride of silver and the iodide, as well as the chloro-bromide are not found in any notable quantity except in the calcareous rocks; whilst the sulphites and sulpho-arseniates are found in the arsenic coloured or Devonian rocks; in fact the galenas belong more especially to the gneiss or to the slate. The simplest mode of forming an accurate idea of the extraction of the veins of silver, and the changes which they manifest in proportion as the depth of the mine increases, is to suppose that one of these veins cuts all the series of the stratified rocks from the lias to the gneiss included. In the part corresponding to the lias, the chlorides and native silver are met with. Rosi-cler or ruby silver will begin to appear towards the lower part of this formation, and in the arsenica colorada; the sulphuric arseniates with silver and cobalt shew themselves next, and finally the galenas. Some mines in Chañarcillo whose workings have reached to a depth of more than 220 yards, in a great measure realise this hypothesis; whilst in Tres-Puntas, where the lias does not exist, ruby silver and arsenical sulphurites predominate. In fact the mines of Zapallar, situated in the Devonian formation, abound more especially in galenas. It results therefore, from this constitution of the veins of silver, that their richness should be found in proportion to the number of these formations through which the veins pass, and that their richness should diminish regularly as the depth increases. The mantos are nothing more than the overflowings of the superior part of a vein in some porous bank or strata, which circumstance explains the exceeding richness of some of these, as the Mantos de Mandiola, and de Ossa, in Chañarcillo, and that of the Presidente în Cabeza-de-Vaca. ON PROPERTY AND WORKINGS IN MINES. The property in mines and the working of them are regulated in Chile by the Spanish law, known as the Mining Ordinances. The pertenencia or property in one mine is a rectangular space of ground 208 yards long, measured over the course of the vein, and from 108 to 208 yards in width, according to its direction or slope. However little we reflect on the peculiar construction of silver veins, which always consist of small productive spaces separated by spacious places in every respect sterile, it is easy to perceive the disproportion which exists between the small extent of a pertenencia or mine, and the nature of the veins which are to be worked for a profit, for it may often occur that the mine covers a space entirely without metals, in which case the property, as stipulated by the Ordinances, is an entire delusion. The miner, having incurred heavy expenses, finds himself at the limits of his mine, and at the point of realising a rich ore that will reimburse his outlay, but after long labours and his heavy expenditure, he is denied the opportunity of touching it, because it is discovered a few metres beyond the limits of his allotted space. As the same Ordinances prohibit, on the other hand, any miner who is not a discoverer from asking for more than one pertenencia near the same vein, it always happens when a discovery is made that a great number of miners hurry to solicit each his pertenencia or allotment, on the principle vein or some of its ramifications; so that a mineral deposit, when discovered, is soon found to be divided into an infinite number of small allotments, whose titles become afterwards a source of interminable lawsuits. Thus, from the first step, the Chilian miner finds himself surrounded by difficulties originated by the laws which should be his protection. In addition, every miner being opposed to permit workings to be made on his allotment for the purpose of discovery or examination, the course and arrangement of the veins in a mineral deposit cannot be profitably studied. Each one works according to his fancy, and without data to guide his labours, and the greater portion of capital spent in these works is found to be absorbed in fruitless toil. Every working of a mine commences by what is termed the Ordinance Well (Pozo de Ordenanza). This is a shaft, generally an inclined one, of ten varas depth, the varas being thirty-three English inches, by one and a half varas diameter, which must be made upon the vein in the term of ninety days, reckoned from the date on which the allotment was granted. The works continue to proceed in the same direction until a metal is found rich enough to be beneficial. The walls or space is then fitted up to serve for the extraction of the metals. This operation, which is called Circar la Veta, consists in working a lateral opening so as to leave one side of the vein uncovered: and when it is thought that this lateral run is sufficiently prolonged, the works on these walls are suspended to proceed with the breaking of the vein, an operation which is always performed in the presence of one or more of the major domos. The metalliferous portions are immediately collected, and carried to the cancha, an enclosed yard, under the vigilance of one of the overlookers or major domos. These canchas are the yards or workshops where the metal is selected,--an operation which is performed by workmen called chancadores, and are of two sections; the one termed raspar el metal, consists in selecting all the profitless stones, and the other in reducing the metal into fragments small enough to pass at once into the trapiche, or Chilian grinding mill. The last operation, which involves much expense, might be made with more economy by means of a small bocarte, or other very simple machine. The usual custom is to divide the metal into two lots, the one composed of the richest pieces being called pinta, and the less valuable despinta. When the trecho, or space of the metallic vein, is of sufficient extent, a second fronton or space is fitted up below the first one, and thus successively leaving between each run an unexcavated portion of six to eight decimetros to sustain the front of the vein, known as the puente, or bridge. These puentes, which the law prohibits being removed under severe penalties, might be usefully substituted by platforms. Thus the metals which they contain would be utilised, as they often represent considerable value, and at least redeem the great outlay occasioned by the removal of stones and barren parts of the vein. When this first portion of the vein in beneficio has run out, the shaft is prolonged, perhaps in the same direction, or it may be in the other direction, which is called giving another turn, and so on successively. It results from this mode of working mines that, at the end of a certain period every shaft or roadway must be in form of the letter Z, communicating |