in gold mines, silver mines, or other mines; nor do other miners neglect them if they are found in stone quarries, or in their own veins; their value is usually indicated by their taste. Nor, lastly, does the miner fail to give attention to the solidified juices which are found in metallic veins, as well as in their own veins, from which he collects and gathers them. But I will say no more on these matters, because I have explained more fully all the metals and mineral substances in the books “De Natura Fossilium.”
But I will return to the indications. If we come upon earth which is like lute, in which there are particles of any sort of metal, native or rudis, the best possible indication of a vein is given to miners, for the metallic material from which the particles have become detached is necessarily close by. But if this kind of earth is found absolutely devoid of all metallic material, but fatty, and of white, green, blue, and similar colours, they must not abandon the work that has been started. Miners have other indications in the veins and stringers, which I have described already, and in the rocks, about which I will speak a little later. If the miner comes across other dry earths which contain native or rudis metal, that is a good indication; if he comes across yellow, red, black, or some other “extraordinary” earth, though it is devoid of mineral, it is not a bad indication. Chrysocolla, or azure, or verdigris, or orpiment, or realgar, when they are found, are counted among the good indications. Further, where underground springs throw up metal we ought to continue the digging we have begun, for this points to the particles having been detached from the main mass like a fragment from a body. In the same way the thin scales of any metal adhering to stone or rock are counted among the good indications. Next, if the veins which are composed partly of quartz, partly of clayey or dry earth, descend one and all into the depths of the earth together, with their stringers, there is good hope of metal being found; but if the stringers afterward do not appear, or little metallic material is met with, the digging should not be given up until there is nothing remaining. Dark or black or horn or liver-coloured quartz is usually a good sign; white is sometimes good, sometimes no sign at all. But calc–spar, showing itself in a vena profunda, if it disappears a little lower down is not a good indication; for it did not belong to the vein proper, but to some stringer. Those kinds of stone which easily melt in fire, especially if they are translucent (fluorspar?), must be counted among the medium indications, for if other good indications are present they are good, but if no good indications are present, they give no useful significance. In the same way we ought to form our judgment with regard to gems. Veins which at the hangingwall and footwall have horn-coloured quartz or marble, but in the middle clayey earth, give some hope; likewise those give hope in which the hangingwall or footwall shows iron-rust coloured earth, and in the middle greasy and sticky earth; also there is hope for those which have at the hanging or footwall that kind of earth which we call “soldiers' earth,” and in the middle black earth or earth which looks as if burnt. The special indication of gold is orpiment; of silver is bismuth and stibium; of copper is verdigris, melanteria, sory, chalcitis, misy, and vitriol; of tin is the large pure black stones of
