Tabular statement showing the position and character of the principal mines of Northern Mexico, from 1863 to 1865.

Mines.

Naghuila

Quartz and iron ore. Galena, zinc, carbonate of lead, iron

Mines.

Location.

Strike.

Dip.

N. 80° E..

Perp
80° N

Quartz

Chalcedonic quartz Galena, blende, copper pyrites, &c..

CHILL.

The silver regions of Chili were represented by a large and brilliant collection of the ores forwarded by the government commission at Santiago, and accompanied by a catalogue and explanatory notes upon the mineral wealth of Chili, by M. Domeyko, inspector general of the mines of Chili, and first professor in the School of Mines at Santiago. These notes were published in French, in connection with the statistical notices by the commission. The following data are translated and condensed from those of M. Domeyko.

The principal branches of mining industry in Chili are: 1. The production of copper; 2. The production of silver; 3. The production of gold, cobalt, and nickel; 4. The production of coal.

The most important and profitable of all is the production of copper. This is exported chiefly in the ore, or reduced to a matt or regulus, much of which contains silver.

The value of the annual silver production of Chili is about $2,000,000, The most important and productive mines are in the department of Copiapo. In this department the silver-bearing formation, with the exception of some veins of argentiferous copper ore in the central Andes, is an argillaceous limestone of the Jurassic epoch, and the veins or deposits are usually found near the junction or contact of this formation with the eruptive rocks. The principal mines, and which have furnished nearly all the silver for exportation and for coinage at the Santiago mint. are those of Chanarcillo and Tres Puntas.

Chanarcillo.-The discovery and opening of these mines dates from 1831. and a description of them was given for the first time by M. Domeyko. in 1846. Since that time the field of mining has been considerably enlarged. Some of the principal mines are the Valenciana, Colorado, and St. Francisco el Delivio. There are in all some 85 or 86 mines belonging to different proprietors, but very few of them are worked with,profit. A railway now connects these mines with the port of Caldera, and thus. by affording cheap and rapid transportation, the proprietors are enabled to work ores which do not contain more than 1.001 to 0.0015 of silver.

These mines are remarkable for their production of the ore known as horn silver (chloro-bromide) in great quantities and in large masses. The principal varieties of ores now found are native silver, horn silver, and ruby silver. Some fragments of polybasite and of galena are found from time to time, but in general these and pyrites, blende, and sulphuret of copper are very rare.

1

A very good description of these mines is also given by Dorsey. In

Notice Statistisque sur le Chili et Catalogue des Mineraux Envoyés, á l'Exposition Universelle de 1867; 8vo.; Paris, 1867. Circulated at the Exposition.

Annales des mines, 1846.

3 Mining Magazine and Journal of Geology, &c., I, 102. See also "Silver Ores and Sil ver Mines," p. 59.

1859, 78 mines were worked, 1,200 men were employed, and the production was 8,000 pounds of pure silver monthly. From the date of their discovery in 1832 to 1859, the total production was valued at $60,000,000, nineteen-twentieths of which came from 25 mines.

The collection at the Exposition contained a variety of specimens from the Chanarcillo mines, Valenciana, Dolores, and Loreto. These were chiefly native silver and the chloro-bromide, with some specimens associated with native arsenic. Nos. 186 to 207 were interesting specimens of red silver ores, of different varieties and forms. No. 209 was a mass of pure chloro-bromide from a vein nearly an inch wide, without any gangue in the mine Descubridora. The whole series was accompanied by a suite of the rocks which are traversed by the silver-bearing veins. One specimen contained an ammonite taken from the Loreto mine.

Tres Puntas mines.-These mines were discovered later than those of Chanarcillo, and have been about 20 years under exploitation. They are situated northeast of Copiapo, further from the coast than those of Chanarcillo, but in the midst of a formation which appears to be of the same age and has a similar mineral composition. The district has also a much greater extent, and in the centre of it there is a mass of eruptive diorite which is not seen at Chanarcillo.

The chief difference between the mines of the two districts is that at Chanarcillo; the mines have produced and are still yielding large masses of chloro-bromide of silver and iodide of silver, which, in depth, pass into red silver and arsenical ores, while at Tres Puntas the mines have not yielded chloridized ores, except at the outcrops of the veins, but instead, they have given immense quantities of amorphous antimonial, and arsenical red silver ores, mixed with sulphuret of silver, with polybasite, arsenical cobalt, and, above all, native silver disseminated in the midst of the gangues.

The richest and most important of the Tres Puntas mines is called the Buena Esperanza, and it was represented by ten cases of specimens selected and arranged by Mr. Plisson, the engineer and director of the works. This collection contained, besides the product of the Buena Esperanza, some choice mineralogical rarities from other localities, such as large crystals, and groups of crystals, of light ruby silver from Chanarcillo, masses of native arsenic, native amalgam, miargyrite from the mine Alfinhallada; and a new species, a double iodide of silver and of mercury, called tocornalite.

The mines of the district of Aconcagua were also represented in the collection, as well as several other districts and mines of minor importance. There was also an interesting metallurgical collection, showing silver ores and their products in the various stages of mechanical preparation and of treatment for the extraction of the silver and other metals. One series illustrated the process of amalgamation followed in the establishment of Messrs. Ossa & Escobar, directed by Kronnke. This process is said to have received the special protection of the Chilian government by a patent, and to remain a secret.