the veins of San Juan de la Chica, as well as those of the Rincon del Centeno, and the Gigante, are very deserving of the attention of the Mexican miners. Was it to be expected that superficial works which were merely begun, should in the very first years, yield a net profit to the shareholders?

The mercury mines of New Spain are of very different formations. Some are found in beds in secondary earths; and others in veins which traverse trap porphyries. At Durasno, between Terra Nueva, and San Luis de la Paz, cinnabar mixed with a number of globules horizontal bed of native mercury, forms a (manto) which reposes on porphyry. This manto which has been pierced by pits of five or six metres ✶ in depth, is covered with beds Lof slate clay, which contains fossil, wood, and coals. On examining the roof of the manto, we find from the surface, first a bed of slate clay (schieferthon) impregnated with nitrate of potash, and containing fragments of petrified vegetables; then a strata of slate coal (schieferkohle) of a metre † in thickness; and lastly slate clay which immediately covers the cinnabar mineral. From this mine there was drawn, eight years ago, in a very few months

16 or 19 feet.

+ 3.28 feet.

nearly 700 quintals of mercury which were not sufficient to pay the expences of working, although the ore contained a pound of mercury for every load of three quintals and a half. The carelessness with which the mine of Durasno was wrought, has been so much the more prejudicial, as on account of the small degrees of solidity of the rock of the roof, and its horizontal position, it very frequently fell in. The mine is at present drowned, and to resume the operations would not be attended with profit. It has constantly enjoyed very high celebrity in the country, not on account of its wealth which is inferior to that of the veins of San Juan de la Chica, but because it admitted of being wrought sub dio, and because its produce was very abundant. They attempted in vain to discover a second bed of mercury ore below that of Durasno.

The cinnabar vein of San Juan de la Chica, is two or three and sometimes even six metres in extent (puissance). It traverses the mountain of los Calzones, and extends to Chichindara. Its ores are extremely rich but by no means abundant; I have seen there masses of compact and fibrous sulphuretted mercury of a bright red, twenty centimetres in length, and three in thickness; and these specimens resembled

* 7.87 inches by 1.18. Trans.

from their purity the richest produce of Almaden and Wolfstein in Europe. The mine of Chica has been only yet wrought to the depth of fifty metres; and it is found, and this geological fact is very remarkable, not in freestone or slate, but in a true porphyritic pitch stone (pechstein-porphyr) divided into balls with concentrical beds of which the interior is lined with mammelonneous hyalite (müllerisch-glass). The cinnabar and a little native mercury, are sometimes observed in the middle of the porphyritic rock at a very considerable distance from the vein. During my stay at Guanaxuato, ouly two mines were wrought in all Mexico, those of Lomo del Toro, near San Juan de Chica, and Nuestra Señora de los Dolores, a quarter of a league to the south-east of the Gigante. In the first of these mines a load of mineral yields from two to three pounds of mercury; and the expences of working are very moderate. The mine of the Gigante from which there is even drawn six pounds of mercury per load (carga) of mineral, furnished from 70 to 80 pounds weekly; and it is wrought on the account of a rich individual Don Jose del Maso, who has the merit of having first excited his countrymen during the last war to the working of mercury mines, and the manufacture of steel. The cinnabar

*164 feet Trans.

extracted from the veins of the 'mountain del Fraile, near the Villa de San Felipe is found in a porphyry with hornstone base which is traversed by veins of tin, and is undoubtedly more antient than the porphyritic pitchstone (pechstein porphyr) of Chica.

America in its present state is the tributary of Europe with respect to mercury; but it is probable, that this dependance will not be of long duration, if the ties which unite the Colonies with the mother country remain long loosened, and if the civilization of the human species in its progressive motion from East to West is concentrated in America. The spirit of enterprize and research will increase with the population; the more the country shall be inhabited, the more they will learn to appretiate the natural wealth which is contained in the bowels of their mountains. If they discover no single mine equal in wealth to Huancavelica, they will work several at once, by which the united produce will render the importation of mercury from Spain and Carniola unnecessary. These changes will be so much the more rapidly operated, as the Peruvian and Mexican miners shall feel themselves impeded by the want of the metal necessary for amalgamation. But let us enquire what would be the consequence to the silver

mines of America, if in the midst of the wars by which Europe is oppressed, the mercury mines of Almaden and Idria, should no longer be wrought.

I have mentioned the mineral depositories of New Spain, which if examined with care, and worked with constancy, may produce one day a very considerable quantity of mercury. The period approaches when the Spanish Colonies being more united together, will be more attentive to their common interests; and it becomes, therefore, of consequence to take a general view of the indications of mercury observable in South America. Mexico and Peru, instead of receiving this metal from Europe, will one day perhaps be able to supply the old world with it. I shall confine myself to the knowledge which I could obtain on the spot, and especially during my stay at Lima; and I shall only mention the points where cinnabar has been found, either in veins or beds. In several places, for example, at Portobello, and Santa Fe de Bogota, considerable quantities of native mercury have been collected at small depths in building houses; and this phenomenon has frequently fixed the attention of government. They forget that in a country where for three centuries, bags filled with mercury have been transported on mules from province to province,