The principal gold-producing States are Chihuahua, Sonora, Zacatecas, Guerrero, Oaxaca, Mexico, Lower California, Hidalgo, Chiapas, Coahuila. No less than eighteen of the States of Mexico contain gold-bearing districts. Hydraulic, or _placer_, mining for gold has not been much considered as a source of supply, as there are no great alluvial deposits, so far known, such as exist in other parts of North and South America. Nevertheless, something has been done in this way, principally in the States of Chihuahua and Guerrero. The geological formation, however, does not point the probability of the existence of great alluvial deposits, and the _placers_ take the form of river bars principally. The rise of Mexico's gold-production has been rapid. The country now holds sixth place. In 1893 its value was less than 4 per cent. of that of the silver output, whilst in 1894 it jumped to 14 per cent., and in 1902, 20 per cent. The export of gold bullion in 1890 was only half a million Mexican dollars, whilst in 1903 it had risen to 11-1/2 millions. The value of the total gold production for 1907 was 3-3/4 millions sterling. Among other producing mines is the Providencia, of Guanajuato, yielding gold, silver, and iron. Yet another is the "San Rafael and Anexas," a regular dividend-payer, whose net profits for 1907 are given as three-quarters of a million dollars. The famous region of Tlalpujahua is once more receiving attention. _Copper_.--The rise of Mexico as a copper-producing country has been remarkable. Less than fifteen years ago the Republic was unheard of as a source of the red metal, now it ranks second in the world's output, coming next to the United States with a production for the year 1907 of 56,600 tons. The following States are those which are most important as copper-bearing: Chihuahua, Sonora, Coahuila, Zacatecas, Jalisco, Michoacan, Puebla, Queretaro, Tamaulipas, Lower California, and Colima. In Sonora the following mines are at work: The Bufa Mining and Smelting Company; the Trinidad Mining Company, upon which large sums of money have been spent; the Montezuma Mine, an important enterprise, formed with an outlay of millions of dollars upon its appliances and workings, and having a daily capacity of 250 tons of ore, belonging to American capitalists. The Cananea Consolidated Copper Company, a remarkable enterprise instituted by American capitalists. Cananea is considered to be one of the most important copper regions in the world, and a considerable preliminary outlay made has been justified in the results; the works exporting several thousand tons of copper monthly. It forms one of the most complete installations of its nature. The Yaqui River Smelting and Railway Company is a custom smelter, and affords a market for much local copper ore. There are other copper-producing enterprises under development, and the State of Sonora is thus a most productive source of the red metal.