OF THE PLACES OF MINES

Of these others, little sign can be given, except to go minutely to search the banks of their sides. Among all of these, the truest sign and the one of greatest certainty that can be given is when, upon the surface of the earth, whether high or low, the mineral shows itself clearly to the sight. There are some who highly praise as a good sign certain residues left by standing water; these waters, having rested for some days and being heated several times by the sun’s rays, show in certain parts of their residues various tints of mineral substances. And there are others who are accustomed to take such water and, in a vessel of earthenware, or glass, or other material, cause it to evaporate by boiling until it is completely dried. They then test that coarse earthy matter which remains at the bottom in the place of dregs, either by taste, or by the ordinary assay of fire The process of testing an ore's metal content by melting a small sample in a furnace., or another way at their pleasure. By this means (even if they do not have the exact point), they approach a certain knowledge of the matter.

Thus, with these means and as many more as possible before one comes to the beginning of digging—so as not to throw away the expense—you must certify that the mineral is sufficient where you seek it, and that it is good, and in quantity. Such an effect should be sought as perfectly as possible with every industrious care in places near the roots of neighboring mountains, or at the banks of the same mountain, and likewise all the surfaces where the rock is found exposed by its own nature or by the course of water. This is done on the presupposition that it is almost impossible for such mountains, if they contain minerals, not to send out some exhalation original: "eshalatione"; based on Aristotelian science, it was believed that minerals were formed by "dry" or "moist" vapors rising from the center of the earth toward the surface..

However, it could happen that if they did not do so, it was because of the good quality of the mineral, which might not be of an evaporable nature; or perhaps there was only a small quantity of it; or perhaps because the mountain was large and the mineral still deep down, and perhaps so far inside that its "smokiness" is not sufficient to give a sign. Or perhaps because between the surface and the mineral some stone—such as albazano A term used by Biringuccio for a dense, compact stone, likely a type of limestone or volcanic rock that acts as a cap over mineral veins., or black or white marble, dense and resistant by nature—was found interposed, which does not allow it to pass into the light of the upper surface. In such cases, there could be trees and herbs (as I told you), because the earth that is there retains its virtues and can nourish their roots, not being turned to ash nor burnt by the hot and poisonous mineral vapors. Nor for this reason can the rain waters wash it away with their course, as they do in those places where they find the earth scorched. I have already seen such mountains have upon them very large chestnut groves, cultivated fields, and very large forests of beech and Turkey oaks original: "cerri"; a specific species of oak (Quercus cerris) common in Italy.. So, to conclude for you: by the sign of the harshness and sterility of the mountain, one does not assume that other places cannot have minerals, nor that they should not be sought. But because the signs are according to the natures of the minerals, I will tell you of them more specifically in the sections on their own mines. Here I have only wanted to speak in general to give you a certain first light.

SIMILARLY, to make you more alert, I tell you that all the minerals you find by such signs, or that come into your hands in any way—whether they be in stone, earth, or sand—beyond the first appearance which shows you they are metal ores, you must consider the weightiness they have...