Page:Mexico in 1827 Vol 2.djvu/405

Rh all the Mines it is observed that the silver mixed with arsenic is found only in the deepest workings.

Iron pyrites (schwefelkies) abound in the higher levels, and it is to them that the red colour of the ores extracted from these levels is to be attributed: they are prepared by fire for the arrastres, when the sulphur evaporates, and leaves a red oxyd of iron; which distinguishes these montones, as the blue colour does those in which arsenic predominates.

The Colorados, as I have already observed, only occur at a certain distance from the surface.

In a new mine, worked by the Cura of Angangeo (San Severiano), the transition from the Colorados to the ordinary metals, occurs within a space of twenty varas from the mouth of the shaft; and from the moment that this line is passed, magistral becomes necessary for the amalgamation of the ores, although a little higher it is not required.

The following is a fair estimate of the expences of extraction and amalgamation at Angangeo, per monton, of ten cargas, (each of three quintals):—