Iquique, &c. are all wrought with more or less profit, according to the skill of the proprietors or managers.  It is generally believed that the Creoles have a very perfect acquaintance with the minerals, from experience, and with the art of treating them, so as to obtain the largest profit; but, when their utter ignorance in all other arts is considered, their constant going on in the old beaten track, and their enormous waste of quicksilver, one is tempted to believe that our European miners might conduct their works to still greater advantage.

The most perfect silver that is brought from Peru is in the forms called pinnas by the Spaniards, being extremely porous lumps of silver, as they are the remainder of a paste composed of silver dust and mercury, whence the latter being exhaled or evaporated, leaves the silver in a spongy mass, full of holes, and very light.  This is the kind of silver which is put into various forms by the merchants, in order to cheat the king of his duty; wherefore all silver in this state, found any where on the road, or on board any ship, is looked upon as contraband, and liable to seizure.

In regard to the art of refining, I propose to shew the progress of the ore, from the mine till it comes to this spongy mass or cake.  After breaking the stone or ore taken out of the veins, it is grinded in mills between grindstones, or pounded in the ingenious reales, or royal engines, by means of hammers or beetles, like the mills for Paris plaster.  These generally have a wheel of twenty-five or thirty feet diameter, with a long axle or lying shaft, set round with smooth triangular projections, which, as the axle turns, lay hold of the iron hammers, of about two hundred-weight each, lifting them to a certain height, whence they drop down with such violence that they crush and reduce the hardest stones to powder.  The pounded ore is afterwards sifted through iron or copper sieves, which allow the finest powder to go through, the coarse being returned to the mill.  When the one happens to be mixed with copper or other metals which prevent its reduction to powder, it is roasted or calcined in an oven or reverberatory furnace, and pounded over again.

At the smaller mines, where they only use grindstones, they, for the most part, grind the ore along with water, forming it into a liquid paste, which runs out into receivers.  When grinded dry, it has to be afterwards mixed with water, and well moulded up with the feet for a long time.  For this purpose, they make a court or floor, on which that mud, or paste of pounded ore and water, is disposed in square parcels of about a foot thick, each parcel containing half a caxon, or chest, which is twenty-five quintals or hundred-weights of ore, and these parcels are called cuerpos, or bodies.  On each of these they throw about two hundred-weights of sea-salt, more or less, according to the nature of the ore, which they mould or incorporate with the moistened