Capilla de la Bufa. It is worthy of remark that several kinds of igneous rocks occur near each other on this mountain. The observer will see that the city is built in a valley, surrounded by rolling hills, which contain numerous mines. He stands on top of a ridge that rises from the great table-land. To the westward lies the spur of the Sierra Madre, which extends nearly to the Pacific coast. There are many low ridges running north and south, that are situated on the eastern and northern sides of the Zacatecas range. The country is very barren, scarcely a particle of vegetation being visible. The broad plain below has an elevation of about 7,000 feet, and there are nine small lakes of salt and carbonate of soda in this plain, a few miles from Zacatecas. This salt is transported to Guadalupe for use in the silver-mills. The geological formation of this district has been compared by Humboldt to that of Switzerland.
The mines next demand attention. In mineral wealth Zacatecas is the richest State in Mexico. The district, however, which includes the city, does not rank first. In 1804 Humboldt placed Zacatecas third in a list of the principal mining towns.
Guanajuato ranks first and Catorce second in the production of the precious metals. The Veta Grande, or great vein, is next in magnitude to the Veta Madre of Guanajuato. Its average width is about 25 feet, and in a few places it has a breadth of 75 feet, although the entire mass is not metalliferous. The mines of Zacatecas began to be worked in 1548. Up to the year 1732 they are said to have produced the enormous sum of $832,232,880, on which a tax of $46,523,000 was paid to the Spanish treasury.
About 1728 the mines of Zacatecas yielded $1,800,000 annually, which was then estimated as one fifth of all the silver coined in Mexico.
During the War of Independence, the amount of pre-
