Though the fame of Bolivia as a mining country has been gained chiefly by the enormous production of the Potosí and Huanchaca silver mines, these colossal treasures do not by any means represent all the mineral wealth stored in its mountains and carried down its streams. Almost every known metal exists in some section of the country, and silver, tin, and copper are found in several districts that have become celebrated, and rank among the richest in the world. Colquechaca silver, Oruro tin, and Corocoro copper are known in all the great markets and represent the best quality of these valuable metals to be found. The geologic formation of a country so noted for valuable ores is interesting for the relation it bears to these deposits. Of the mountain systems, which are its chief feature, says an eminent authority, the Coast Range is essentially volcanic, tertiary formations are met with on the high plateau between the Coast Range and the Cordillera Real, and the latter, on the eastern side, presents a vast extent of Silurian slates and shales, usually tilted at high angles and frequently bent and distorted. Fossils are scarce, though the ancient ripple and rain marks are extremely clear and abundant. Trilobites are met with in the valleys to the southeast of La Paz. The carboniferous system appears to exist along the extreme east of the Andes and indications of petroleum are met with at various points in the foothills. Along the southern part of the plateau there is an extensive formation of trachytic porphyry which appears to have been ejected and to have spread over the older rocks. The ravine in which the city of La Paz is situated cuts through and exposes a horizontal layer, some twenty feet thick, of volcanic ashes with fragments of pumice stone, evidently deposited under water although it is now buried some six hundred feet below the surface of the plains; further south this layer crops out at various points and is visible for some seventy miles. Probably it was ejected from the Sajama and neighboring volcanoes at the time when the great lake, of which Titicaca and Poopo are the surviving features, occupied the entire plateau. Eruptions of porphyritic and other igneous rocks are seen at many points along the eastern side of the tableland, breaking through and distorting the older shales and slates and forming a distinctive feature of all the silver and tin mining centres.

The serrania in which the silver mines of Colquechaca are located is in the heart of one of the richest mineral regions of the globe. Colquechaca is the provincial capital of Chayanta in the department of Potosí, and is situated midway between the railroad town of Challapata and the city of Sucre. It has been a mining centre for hundreds of years, though under Spanish rule the mines were worked only in a superficial and primitive way; and when the War of Independence put a stop to all mining industry, they were abandoned, as were nearly all the great mines of the country. About twenty-five years ago the exploitation of the Colquechaca minerals was established on a practical and permanent basis, and since that time the mines have yielded nearly a hundred million bolivianos. The Colquechaca silver ores yield in some instances two thousand seven hundred ounces to the ton, these mines being renowned throughout the world for the high-grade rosicler, which is found in abundance. The Compañía Colquechaca Aullagas de Bolivia is the principal owner of the mines of this district, controlling six socavones, in which several miles of railway are operated, equipped with freight cars for hauling the metal out of the mine. A traction engine and a Cornish pump have been established, and the company has four steam engines and two foundries in connection with the mines. The ores are treated in the ingenios of Rosario and Palca. Since the closure of the Indian mints to the free coinage of silver in 1893, and the consequent heavy fall in the price of the metal, Colquechaca has been worked for other metals as well as silver, the production of this mineral being necessarily reduced. The same circumstances have prevailed in nearly all the silver-mining districts, though the metal is still produced in considerable quantities in Cinti, Porco, Portugalete, Andacaba, and other well-known silver mines. It is probable that with the completion of the railway system, the improved facilities for transportation will revive this industry throughout the whole country with wonderful results.

At present, Bolivia is gaining worldwide fame by the enormous quantity and excellent quality of tin which the country produces. This metal has not as yet been found anywhere in the Coast Range of the Andes, but it abounds in the Royal Range. Mr. John Minchin, an authority on everything connected with Bolivian mines, says that ores running as high as forty or fifty per cent of fine tin are not uncommon, and under favorable circumstances as low as three per cent may be worked to a small profit, but the average contents in fine tin of ores worked by the larger enterprises may be estimated at from eight to ten per cent. Ores worked more especially for silver also frequently contain from two to five per cent of tin oxide, which in such cases is cheaply extracted from the tailings resulting from amalgamation or lixiviation. Water power is scarce on the plateau, and, in consequence, steam power is employed in the mining establishments, native fuels being chiefly used, as coal costs eight pounds sterling per ton at the railway stations. Of late years several anthracite producer gas engines from the Deutz works, in Germany, have been introduced, with very satisfactory results as regards economy, the working cost being about twopence per horse power, as compared with threepence for native fuel and fourpence to fivepence for steam coal. “In spite of all the care at present possible in the concentration of tin ores,” says Mr. Minchin, “there is commonly a loss of from twenty to twenty-five per cent, though it is hoped that this may be reduced later on with improved methods of treatment.”

The total tin production of Bolivia for the year 1905, reduced to bar tin, was eighteen thousand tons. The development of this branch of mining industry is still in its infancy in this country, new tin deposits being found constantly, while the few mines that were discovered by the Spaniards and the natives long ago are practically new in exploitation, never having been worked to any extent formerly, as this metal, unlike gold and silver, was not regarded as valuable in the earlier days. The history of tin mining is of comparatively recent origin, the first tin mines exploited in Europe having been those of England and Germany, discovered in the thirteenth century. An interesting monograph published by the Oficina Nacional de Inmigracion, Estadistica y Propaganda Geográfica of La Paz gives information to prove that the pre-Columbian inhabitants of the province of Larecaja, and of other tin-bearing regions of Bolivia, discovered tin and worked it, but without being aware of its full value as a metal. Archæological investigations show that tin, amalgamated with copper, was used by the Aymará and Quichua Indians for making war weapons and other objects, though the bronzes of this composition indicate only a slight knowledge of its metallurgical possibilities. These bronze huacas are found with much more frequency in ruins of Quichua construction than in those known to be of Aymará origin. This is the more remarkable because the greatest abundance of tin is found in the territory occupied by the Aymarás. Tin mines were exploited during the Spanish colonial period, but only on a very limited scale. In an old document published in 1640, the author, a curate of Potosí, calls attention to rich mines of tin in the provinces of Chayanta, Larecaja, Oruro, and elsewhere, which he says “were worked by the Indians in the time of the Incas, and which have since been exploited by the Spaniards.”

The tin mining region of Bolivia is divided into four districts: La Paz in the north, Oruro in the centre, Chorolque in the south, and Potosí in the east. In the department of La Paz, the beautiful snow range which extends from Illimani to Sorata, and which is known to all travellers who cross Titicaca, because of the enchanting prospect it offers as seen from the lake, marks a region rich in minerals, especially in tin, silver, iron, and bismuth. Huayna Potosí, with its twin peaks, Kaka-aca and Locka, is one of the richest cerros of this district, and it has been exploited at various periods for silver, bismuth, and tin, which are found here in abundance. With the investment of large capital, this mountain might prove an enormous producer of tin, as it is rich in good ore. A few miles distant from Huayna Potosí the peak of Milluni may easily be distinguished among the towering summits. It is the site of valuable tin mines and yields rich iron ore. The width of the silver veins in this mine varies from two to thirteen feet, and enormous quantities of almost pure metal are taken out of them, with very little expense. The greater part of the work has been done on the surface, in the outcroppings, by means of open cuts, so that the interior of the Cerro is hardly known. One socavón only has been opened within the mine to a depth of about two hundred and fifty feet, with two broad and well built galleries. The mines of Huayna Potosí and Milluni are exploited by a French company, having headquarters in Paris, and an office in La Paz. Milluni being so close to La Paz, and the roads in good condition, cargoes can be taken in carts direct from that city or from the port of Chililaya on Lake Titicaca, and the rate of shipment from Milluni to Mollendo is less than that charged for ores going from Oruro to Antofagasta. In both mines lumber for construction purposes is cheaper than in La Paz, as it comes chiefly from Songo in the Yungas, only a few miles distant, though for Oregon pine the same price is paid as in La Paz, about fifteen cents, gold, a square foot. Both Huayna Potosí and Milluni are worked for tin at an altitude of sixteen thousand feet above the sea. Chacaltaya, a peak which belongs to the same group, is also under exploitation, and with more favorable conditions may develop very rich lodes, as it has not yet been thoroughly worked.

Probably the richest tin mines of the La Paz district are those of Inquisivi, and especially Quimsacruz. Recently these mines have been producing enormous quantities of the valuable metal, and, according to the noted French geologist Dereims, the lofty range of Tres Cruces, otherwise known as Quimsacruz, which rises to an altitude of about twenty thousand feet above sea level, contains the richest minerals in all Bolivia. This section of the Cordillera Real begins south of the peak Illimani, on the opposite side of the natural cut in the great range through which the La Paz River flows on its course northward; and it extends entirely across the southern part of the province of Inquisivi, where it borders the department of Oruro. In this noble range tin mines are being worked with magnificent results, and mineralogists of eminent authority pronounce this to be the richest tin-mining district to be found anywhere, equal to Malacca, which is generally supposed to have the finest tin mines in the world. Not only tin, but silver and other metals abound here. The Colquiri mine was worked by the Spaniards for chloride of silver, the deepest veins having been exploited one hundred and seventy-five feet below the surface, and at water level. One vein is recognizable for three miles on the surface by débris scattered along the course. A tunnel of one thousand feet in length still exists, cutting this lode above the level of the water, and another vein as long as the one already mentioned. Evidently tin as well as silver was extracted in those days, though only in small quantities, owing to the indifference universally shown by the Spaniards for tin mining. The mineral wealth of Inquisivi has recently attracted new enterprises, and several important mines have been discovered within the past year or two. The mines of Monte Blanco are enormously productive, as are also those of Avicaya, owned by Abelli and Company, and the Totoral and Chuncho mines, in the Cerro of Challa Grande. These mines are situated near the base of the Cerro, Chuncho being at the greatest altitude, near the centre, Totoral further down the slope, and Avicaya four hundred feet below Totoral. On the opposite side of the Cerro are rich veins of silver, and it is noteworthy that all the tin mines of Quimsacruz are on the south side of the range, the mineral veins on the eastern slopes being silver, while on the north is found auriferous quartz. Tin mining in the mountains of Tres Cruces offers a particularly promising prospect, as is proved by the new discoveries of this valuable metal which are constantly being made in this region.

In the tin-mining district of Potosí are included the rich cerros of the province of Chayanta, in which are found the mines of Uncía and Llallagua, both in the Cerro de Uncía. This mountain was formerly noted for the rich quality of silver taken from its mines, but at present it is worked chiefly for tin. The Compañía Minera Uncía, which is under the direction of Mr. John B. Minchin, owns several of the principal mines of the Cerro, which are exploited according to the most modern methods and are producing a superior quality of tin. The output of this company’s mines for the year 1905 amounted to four hundred and eighty-five tons of two thousand two hundred and forty pounds. Modern machinery is used in the treatment of the ores by lixiviation and other processes. The Salvadora mines, of Uncía, owned by Don S. Patiño, are also yielding a large quantity of rich tin under the modern system of treatment which the ores receive in the well-equipped establishments. Llallagua is the centre of some of the most valuable tin mines in Bolivia. The name of one of the leading statesmen of the country, General Sainz, is associated with the exploitation of the chief of these mines, which owe their development to the Empresa Llallagua, of which he was the organizer and chief owner. Last year General Sainz negotiated with a Chilean-Bolivian syndicate, which agreed to purchase this valuable property. The capital stock of the new company is one hundred thousand pounds sterling, divided into one hundred shares of one thousand pounds sterling each, and the directors are leading financiers of Chile and Bolivia. The mineral wealth of Llallagua is comprised in three mines now under exploitation. La Blanca, San José, and Quinsachata, which cover a territory of about one thousand acres. The mines are situated about forty miles east of Challapata, and three miles from Uncía. A cart road connects the mines of both Llallagua and Uncía with the railway, the construction of this highway having been completed at the expense of the mine owners, General Sainz and Mr. Minchin. The new railroad now being built from Oruro to Potosí will pass through these mining properties. The production of the Llallagua mines is estimated at five tons daily of barrilla de estaño, or concentrate tin, of seventy per cent tin, of the best quality. The establishments in which the ores of these mines are treated are equipped with modern machinery, and a trolley connects the mines with the ingenio for concentration. The minerals from this part of Bolivia are shipped by way of Antofagasta, while those of Huayna Potosí, Milluni, and other mineral districts in the neighborhood of Lake Titicaca, are carried across the lake to Puno and thence to Mollendo.

On the Titicaca plateau, about fifty miles southwest of La Paz, are located the extensive copper mines of Corocoro, the richest in South America. Like other famous mines of Bolivia the wealth of Corocoro was discovered long ago by Indians, but it is only within recent years that its treasures have been exploited with important results. The copper lodes of Corocoro exist in a sandstone formation, the metal being met with in solid fragments and in fine grains disseminated through the matrix and requiring only grinding and concentration to obtain a product containing some eighty-five per cent of copper barrilla, in which form it is exported. A few of the huge pieces of metal found at Corocoro have been placed on exhibition in the museum of La Paz, and are considered among the largest ever found in this form, measuring many feet in circumference. These masses are called charquis. The abundance and rich quality of Corocoro copper entitles it to rank second only to the famous mines of Lake Superior in the United States. There are numerous companies engaged in exploiting the riches of the Corocoro region, though probably the largest mining interests here are held by a French company under the direction of Señores Berthin, who control several mines. The output of the Corocoro mines amounts in value to about two million bolivianos annually. In addition to Corocoro, which represents the principal wealth of copper-producing Bolivia, there are promising deposits in various sections of the departments of Potosí, Chuquisaca, and Cochabamba. The Compañía Cobrizos de Bolivia has important mines of both copper and silver situated about six miles from Rio Grande near the Antofagasta and Oruro Railway, southwest of Uyuni, and in the province of Frias, near the city of Potosí, metals which some experts claim to be superior in quality and equal in quantity to those of Corocoro have been found, though the mines are not worked, because of the lack of capital for their development. In the province of Porco, in the canton of Yura, midway between Huanchaca and Potosí valuable mines of copper, as well as of gold, have recently been discovered, and it is only a question of a short time when large capital will be invested for their development. The railway which is to join Uyuni with Potosí will pass through one of the richest mineral regions of the globe, and within twenty-five miles of the mines just referred to. A great opportunity is offered in Yura for the exploitation of the mines, as there is abundance of water, a prime necessity for the economical treatment of the ores. Several of the older mines, worked originally for silver, contain in their ores from ten per cent to twenty-five per cent of copper, but want of capital and high freights have prevented their being worked in modern times for copper. Copper pyrites and other copper ores also exist at many points, but for similar reasons little attention has as yet been given to them. In fact, ores containing anything less than twenty-five per cent of copper would not pay to work and export under present conditions, and, owing to the scarcity and cost of suitable fuel, neither could such ores be advantageously reduced to bar copper in the country. The construction of more railways is a vital necessity in Bolivia, the Antofagasta line being taxed to the utmost to handle the abundant traffic, with the result that freights are necessarily high, rendering the importation of machinery, fuel, and general merchandise extremely costly, as well as making the export of produce enormously expensive.

Mine owners say that the native labor, although at times somewhat limited, is not so unsatisfactory as might be supposed, the Indians and cholos working steadily and peaceably as a rule, though they spend a great deal of time in their numerous fiestas, when they always require an extra holiday for getting sober and ready for work again. A great many mine owners are urging the modification and improvement of the mining laws, which, though good in principle, are frequently distorted in their application, owing to the interpretation put upon them by badly informed petty authorities. The present government is devoting careful attention to this as well as to other problems which affect the development of the national industries.

The mining laws of Bolivia are liberal and offer few restrictions. All metalliferous substances belong to the state. Anyone who enjoys civil rights may obtain thirty pertenencias of new mining property, and as much as he wants of mining lands already worked. The preferred right is given to the first who presents his petition for the concession. A pertenencia is a hectare, about two and one-half acres, of undefined depth, which is measured in the direction requested. The method of exploitation is optional. Concessions are perpetual, providing that a patente of four bolivianos per lode per annum, and two bolivianos per annum for each pertenencia in placer mines is paid semi-annually. The failure to pay for a year is sufficient cause for considering the concession abandoned. Machinery destined for the exploitation of mines pays no fiscal duties. Inorganic substances, with the exception of those of an earthy nature, are acquired in conformity with the mining law, concessions being given for sixty-four pertenencias in new deposits, and more than that territory in old fields. Ten bolivianos is the sum charged for the writ of adjudication. The preliminary procedure relative to acquiring mines is made in the presence of a special notary resident in the capital of the district in which the desired property is found. The prefect of the department is the authority through whom the concession of pertenencias is transmitted. All matters relative to priority of petition, transgression of limits, and similar causes for complaint, are brought before the ordinary justices. The owner who desires to leave off working his mine must notify the authorities, in order not to be held responsible for the payment of patentes. In case of failure to pay these charges for a year, the mine is auctioned to the highest bidder; and failing a purchaser, it remains in possession of the state, to be given as a concession to the first petitioner.

The mining laws which govern the Cerro de Potosí have frequently required revision. They are, in some respects, distinct from those governing the acquisition of new mines. A great deal of difficulty has been encountered in the past because of the impossibility of marking absolute limits to the mining properties of Potosí. Formerly, the owner who could employ the largest body of workmen and extend his mines most rapidly could swallow up the lesser properties. For instance, if while working a vein the owner strikes through the wall which separates his claim from a neighboring mine he becomes the possessor of the latter. This law has necessitated the keeping of a guard at all points where such an invasion might be feared, and it has frequently proved a source of dissatisfaction. The government has considered various plans for the solution of the problem, and the law has been amended in notable features, but as the Cerro seems to be a great mass of metal it presents unique features for legislation. In some respects the mining laws of Bolivia necessarily differ from those of other countries, the conditions being distinct, but the law-makers are thoroughly conversant with the requirements of the mining districts and the question is studied carefully from every standpoint. From long experience in dealing with the problems that are peculiar to a mining country, the Bolivian people have become informed on all that relates to mining laws and their interpretation, and improvements are constantly being made to advance the progress of this important industry.