The mining industry in Durango is important. Gold and silver are freely found and worked. The great hill of iron has been described elsewhere in these pages. Copper is abundant; tin, cinnabar, sulphur, and coal exist. The numerous mining districts in this state have produced much wealth in the past, and mines and reduction works are encountered strewn over the mountain regions. The great Penoles[38] mining and smelting enterprise at Mapimi is one of the most important in the country. The historic Avino silver mines are worked by British capital. Other numerous modern mining establishments are in operation, which have been brought to much perfection by foreign capital and skill. [Footnote 38: Visited by the Author.] Railways are fairly well developed in this state; the International and the Central being those which traverse it. Zacatecas owes its fame and prosperity in the first instance to its mines, which have been worked from the year 1546 to the present day. The state is situated on the great plateau in the centre of the Republic, at an average elevation above sea-level of 7,700 feet, but embodying a diversified topographical character and climate. Cattle, cereals, and agricultural products generally, are raised to a certain extent. With an area of 25,300 square miles it has a population of about 500,000. The famous capital city of Zacatecas, as described elsewhere, is served by the Mexican Central Railway, which traverses the state; as does also the National. A large number of mines are being worked in this state, and new capital is rapidly coming in. Foremost among British enterprises are the important mines and smelting works of the Mazapil Copper Company, at Concepcion del Oro. The field of minerals is a vast one, and offers inducement to foreign capital. Gold, silver, copper, lead, and quicksilver are all produced, but more capital is required. Remarkable as it may seem, the high region which composes this state produces rubber--the _guayule_, a plant which grows wild in profusion in various parts of the region, and which is in much demand. The little state of Aguascalientes lies to the south of the above region, with an area of somewhat less than 3,000 square miles and a population of 105,000. Its principal source of life is agricultural, but the mineral industry is important. The capital city stands at an elevation above sea-level of 6,100 feet, and the hot-springs of the region give rise to the name of the state and city; which may be described as healthy and attractive. It is traversed by the Mexican Central Railway.