There is no exact notice of the number of mineral districts and single mines abandoned in the State of Coahuila; but the number is considerable, according to the information furnished from 1843 by the deputation of Santa Rosa. Among those deserving a particular mention is that of the Sierra de Timulco and that of Potrerillos, by the good ley of the metals of the mines of the first, and by the uniformity of the veins and not unappreciable richness of the second. These veins run generally from northwest to southeast, and in the course they encounter, scattered about, silver-bearing galena [sulphuret of lead], lead, copper, with sulphuret of zinc. The amount of the consumptions of the mines that are worked is also unknown; but it is known that the gunpowder costs the operators $9 an aroba [of 25 pounds], of lead, $12 a carga of 300 pounds; that of _greta_, $6; copper, of superior quality, $16 the hundred weight; the carga of coal, six _reals_ [three fourths of a dollar], and wood, one _real_ a mule-load. The ruins and the heaps of rubbish manifest that in other times there was much activity in the labor of the mines and haciendas for separating the metals; but to-day there are only in existence some furnaces, which are the least costly, which the miners of Coahuila can use for their metals. This they effect generally in ovens, and in _galemes_ in the open plain. But this method of separating the metals, which Coahuilans have been necessitated to adopt as the least expensive, until quicksilver has notably fallen in price, has not remained stationary, as in other parts of the republic. These simple inhabitants have succeeded, by the force of experiments, in obtaining as a result the power of fusing 25 cargas [of 300 pounds] of metal, with the aggregation of 18 cargas of _greta_, in only one furnace and in the space of twenty-four hours, by consuming only 45 pounds of coal for each carga of metal. There are three companies in that state for working the mines in the mineral district of Ramirez, and another in that of Trinudco. There is no notice of the amount of funds employed, but it is presumed that they are not considerable, by considering the smallness of the fortunes of the inhabitants of the frontier. In government and economy of mines the Assembly of Mineria of the valley of Santa Rosa have jurisdiction, but in litigations the judges of first instance have jurisdiction, to whom a particular law of this state gives authority. In Coahuila, besides silver, there is found virgin iron in masses of considerable volume and of extraordinary value in the Sierra of Mercudo, in Guadalupe, and other points.