The emeralds found here are of a fine, though not very deep, colour; at both places the mother-rock is a dark mica-schist interfoliated with talc-schist, and containing in the Jebel Sikait district augite and hornblende in addition. The mother-rock of the emeralds found in the Urals and in the Salzburg Alps, to be described later, is precisely similar in character. It has occasionally happened that fine emeralds of a good colour, some cut and some rough, together with other precious stones, have been thrown up by the sea on the beach near Alexandria. These stones are apparently part of a sunken treasure, and probably came originally from the ancient mines in Upper Egypt, being similar both in quality and in the character of the minerals with which they are associated to stones known to have come from these mines.
Emeralds from South America were first introduced into Europe at the end of the sixteenth century, and from this period up to the year 1830 all the emeralds, which came into the market were brought from this country.
At the time of the Spanish conquest of South America many large and beautiful emeralds were found in the possession of the Peruvians. The mines from which these stones had been derived were probably at the time of the invasion deserted and filled in by the natives, for the search made for them by the Spanish conquerors was altogether unavailing. They are supposed to have been situated in the Manta valley near Puerto Viejo, from whence is said to have come the emerald the size of an ostrich's egg, which was worshipped by the ancient Peruvians as a deity. However that may be, it is certain that at the present day no emeralds are found in Peru.
The number of stones, which the Spaniards took from the natives and shipped to Europe, must have been enormous. Jose d'Acosta related that the ship by which he voyaged from Peru to Spain in 1587 carried two cases, each of which contained no less than a hundredweight of emeralds. This large importation of emeralds from Peru, together with the abundant yield from the mines soon afterwards discovered in Colombia, had the effect of very considerably lowering the price of these stones, which up to then had been so rare in Europe. The South American emeralds were far finer than any previously introduced into Europe whether from Egypt or elsewhere, and hence emeralds of good quality came to be distinguished as "Peruvian", or "Spanish", just as the finest specimens of other precious stones were given the prefix "oriental", whether they came from the Orient or not. Many of the emeralds now in use as gems are the same stones as those brought over to Europe by the Spaniards from Peru. In most cases, however, their shape has been altered from time to time in order to conform to the passing fashion of the day. It is said that the Spaniards were possessed of the idea that a genuine emerald would withstand a blow from a hammer, and that many Peruvian stones were in consequence reduced to splinters by being subjected to this test.
The Spaniards found the natives of Mexico also in possession of very beautiful emeralds, in any cases cut with great skill into peculiar and characteristic forms, which are not seen elsewhere. Five stones cut into the shapes of fantastic flowers, fishes, and other natural objects were brought to Europe by Cortez. Since nothing is known as to the natural occurrence of emeralds in this country, it is inferred that the ancient Mexicans obtained the rough stones either from Peru or from the mines in Colombia. Though the Spaniards were unsuccessful in searching for naturally occurring emeralds in Peru and Mexico, and could obtain the beautiful green stones only from the treasure stored up in the graves and temples of the ancient Peruvians and Mexicans, they were more fortunate in the country now known as Colombia or New Granada. Here the deposits from which the natives obtained their stones were easily found, and it is from this same source that the emeralds, which now find their way into the markets of the world are for the most part derived.
Besides the Colombian deposits there is no other well-authenticated occurrence of emerald in South America, the existence of the supposed Peruvian deposits being by no means unquestionable. This being so, it has been suggested that the emeralds found by the Spaniards in the possession of the natives of Venezuela and Ecuador, and especially of Peru, were all derived from the Colombian deposits. The term "Peruvian emerald", except when used to describe the quality of a stone, is therefore misleading, South American emeralds being more strictly described as Colombian. Whether emerald mines ever existed in Peru and other parts of South America or not, it is certain that at present the Colombian are the only deposits known.
The Spaniards first learnt of the existence of Colombian emeralds on March 3, 1537. The Indians, who, at the same time, pointed out the source from which the stones were derived, offered a gift of emeralds to the Spanish conquerors. This spot, known as Somondoco, a name still in use, lies nine about twenty-three miles distant from Guateque, close to the waterfall of Nagar, over which the Garagoa flows before joining the Guario, a tributary of the Upia, which in its turn feeds the Rio Meta. The place is situated on the eastern slopes of the Cordillera of Bogota, in latitude about 5° N. and about half a degree east of Bogota (formerly Santa Fe de Bogota) the capital of Colombia. The wild and inaccessible nature of the region soon drove the Spaniards to abandon the workings in spite of the richness of the deposit. No exact records of this occurrence and of the situation of the old mines are in existence, and doubt has sometimes been thrown on the authenticity of the occurrence. It is probable, however, that the majority of emeralds mined in Colombia in former times came from this spot. The deposit at Somondoco was being worked in 1901by an English company, but as yet only second quality stones have been found.
A short time after the discovery by Europeans of Somondoco as a locality for emeralds, another, about 100 miles distant, richer and of greater importance was discovered. This locality is the only region in Colombia at which fine emeralds are now met with. The stones occasionally found in ancient graves or mountain lakes, which latter were the sites of votive offerings, are all of poor quality, while the naturally occurring stones are frequently of admirable colour and transparency.
The mines now under consideration are situated in the country of the Muzo Indians, who for a long while successfully resisted the Spanish attempts at conquest. They were partially subdued in 1555 by the Spanish under Luiz Lanchero, who, in the same year, founded the town of Santissima Trinidad de los Muzos, the present village of Muzo, in the Itoco Mountains. This latter name was at that time applied to the town itself as well as to the mountains.
In spite of the continued hostility of the Indians, the mining of emeralds was commenced in 1558, an old mine in the mountains, of which all trace is at present lost, being first worked. Later, the centre of the workings was situated about two and a half miles from Muzo, work being commenced here in the year 1594. Numerous other mines were opened in the same district in this year, but were afterwards abandoned for various reasons. Some have been reopened and are being worked at the present day.
The district is situated in the Tunka valley in the eastern Cordilleras of the Andes, which branch away near Popayan from the main chain and stretch along the right or east bank of the Rio Magdalena in its northward course. It is a wild, mountainous region, and its inhospitable character, combined with the hot, damp, and unhealthy climate, renders the search for emeralds anything but an easy task. Crystals of emerald, not of very good quality, have been found in few places of this region, so that it is probable that many other emerald localities are still to be discovered.
During the period, which has elapsed since the discovery, these deposits they have been worked with varying success in many different spots; at one time under Government direction, at another by private enterprise. At one time service in the mines was made compulsory for the neighbouring Indians, and this short-sighted policy resulted in so serious a depopulation of the country that mining operations were appreciably hindered by lack of workers. The deposit was at first worked in underground levels; later, open workings were adopted, partly in order to render possible a stricter supervision of the workers and to avoid the loss through thieving of a large proportion of the output. The yield of these mines was on the whole small and extremely variable, the labour of several months being sometimes done without a single find, while on the other hand emeralds to the weight of 100,000 carats would be found in one day. The places at which workings are commenced are chosen entirely at random, for there is nothing to indicate the probability of one spot being more favourable than another. No really reliable statements as to the total yield of the mines are obtainable, but as far as is known it is very variable; thus, for example, in the year 1849 it averaged 12,400 carats per month, and in the 1850 22,386 carats per annum.
The most important mine at the time was situated to the west of Muzo, in latitude 5° 39' 50" N. and longitude 74° 25' W., of Greenwich; it is about 150 kilometres (ninety-four miles) NNW of Bogota, and lies 878 metres (2,897 feet) above sea-level. It has been worked for a long period, but not uninterruptedly; it ceased, for example, in the middle of the eighteenth century in consequence of' a serious fire, and was only recommenced in 1844. The mine has been at one time worked by the Colombian Government, at another leased it to natives or to European companies. In the interest of the whole locality much secrecy is observed in the granting of such leases, so that there are many points on which it is impossible to get information. From 1849 to 1861 the mine was worked by an English company, who paid the Government for this privilege 14,200 dollars ($317,000) and 5 per cent of the net profits. From 1864 to 1875 a French company, under the direction of Gustav Lehmann, paid the Government 14,700 dollars ($328,000) per annum for permission to work all the mines. The number of workers employed in the mines has varied at different times from 100 to 300. The stones were at first sent to London, but later were placed on the market at Paris.
There are several detailed descriptions of the most important of these mines, which agree among themselves very completely. From them we learn that it is situated on the left side of a small mountain valley called Minero, or at the present time Carare, which joins the valley of the Magdalena River towards the northeast. It is 60 metres above the bottom of the valley, and has the form of a funnel, the upper diameter of which measures 200 metres, and the lower 50 metres. On the side towards the mountain it reaches a depth of about 120 metres, but on the opposite side only 20 or 30 metres; its walls are very steeply inclined. The rock in which the mine is excavated is a dark bituminous limestone; this rests on red sandstone and clay-slates, and contains ammonites, which show it to be of Lower Cretaceous (Neocomian) age. The emeralds are found in this rock in "horizontal veins," or, more correctly speaking, in single nests embedded in calcite, which is either dark and bituminous or water-clear like Iceland-spar. Associated with it are very fine crystals of quartz, some water-clear and others green; also brilliant, well-developed crystals of iron-pyrites, having the form of pentagonal dodecahedra, green gypsum, rhombohedra of black dolomite, and finally crystals of parisite, a fluorocarbonate of cerium and other rare metals, named after Paris, by whom the mine was re-discovered, and who held a lease of it for many years.
Diamond Diamond Geology and Mining Diamond Trade
Rafal Swiecki, geological engineer email contact
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