again I could furnish examples of each kind of stringers rejected by the common miners which have proved good, but I know this could be of little or no benefit to posterity.
If the miners find no stringers or veins in the hangingwall or footwall of the main vein, and if they do not find much ore, it is not worth while to undertake the labour of sinking another shaft. Nor ought a shaft to be sunk where a vein is divided into two or three parts, unless the indications are satisfactory that those parts may be united and joined together a little later. Further, it is a bad indication for a vein rich in mineral to bend and turn hither and thither, for unless it goes down again into the ground vertically or inclined, as it first began, it produces no more metal; and even though it does go down again, it often continues barren. Stringers which in their outcrops bear metals, often disappoint miners, no metal being found in depth. Further, inverted seams in the rocks are counted among the bad indications.
The miners hew out the whole of solid veins when they show clear evidence of being of good quality; similarly they hew out the drusy[1] veins, especially if the cavities are plainly seen to have formerly borne metal, or if the cavities are few and small. They do not dig barren veins through which water flows, if there are no metallic particles showing; occasionally, however, they dig even barren veins which are free from water, because of the pyrites which is devoid of all metal, or because of a fine black soft substance which is like wool. They dig stringers which are rich in metal, or sometimes, for the purpose of searching for the vein, those that are devoid of ore which lie near the hangingwall or footwall of the main vein. This then, generally speaking, is the mode of dealing with stringers and veins.
Let us now consider the metallic material which is found in the canales of venae profundae, venae dilatatae, and venae cumulatae, being in all these either cohesive and continuous, or scattered and dispersed among them, or swelling out in bellying shapes, or found in veins or stringers which originate from the main vein and ramify like branches; but these latter veins and stringers are very short, for after a little space they do not appear again.
If we come across a small quantity of metallic material it is an indication; but if a large quantity, it is not an “indication,” but the very thing for which we explore the earth. As soon as a miner who searches for veins discovers pure metal or minerals, or rich metallic material, or a great abundance of material which is poor in metal, let him sink a shaft on the spot without any delay. If the material appears more abundant or of better quality on the one side, he will incline his digging in that direction.
Gold, silver, copper, and quicksilver are often found native[2]; less often iron and bismuth; almost never tin and lead. Nevertheless tin-stone is not far removed from the pure white tin which is melted out of them, and galena, from which lead is obtained, differs little from that metal itself.
Now we may classify gold ores. Next after native gold, we come to the
