_Silver_.--The main lodes in those places enumerated have ranged up to hundreds of feet in width, and form the most potent silver-ore deposits upon the globe. Their extensions in length and depth bear out their importance as metal-producing sources. Thus the Mellado vein, of Guanajuato, measures, in places, more than 300 feet in width; with workings ten miles in length, and extending to a present depth of nearly 2,000 feet. The _Veta Madre_, or "mother lode," ranges from 30 feet to 165 feet in width; whilst others of the famous lodes reach 50 to 100 feet. As to the ore-values, Humboldt, who visited Guanajuato in the height of its production, at the beginning of the nineteenth century, assigned as his calculation a value equal to about 80 ounces of silver per ton _for the whole lode_. For portions of the ore-bodies, and for many of the great _bonanzas_, much higher values have obtained, silver up to 7,000 ounces per ton having been encountered; whilst ores of 1,100 ounces have been frequently exported to Great Britain. The almost fabulous wealth obtained from the silver mines has been shown in the foregoing pages, and these mines are far from being exhausted at the present day. The importance of the Pachuca mines is shown by the statement that they produce six million ounces of silver and 30,000 ounces of gold yearly. Of the population of the city, of forty thousand souls, seven thousand are employed underground. All of the Mexican states are silver bearing, although those which contain the famous mines are the most important, as:--Sonora, Chihuahua, Sinaloa, Zacatecas, San Luis Potosi, Guanajuato, Queretaro, Hidalgo (Pachuca), Mexico. All these states contain numerous mining districts--cities, towns, camps--which it would take too much space here to enumerate. With the exception of the few modern installations most of the mines are worked by the primitive Mexican system of winding up the ore in raw-hide sacks, hauled by means of cables made from _maguey_ fibre, upon a mule-actuated windlass--the _malacate_. In some cases the miners carry huge pieces of ore on their backs, from 100 lbs. to 200 lbs. in weight, along the galleries to the shaft. Interior transport and haulage are primitive.