Page:De re metallica (1912).djvu/43



ANY persons hold the opinion that the metal industries are fortuitous and that the occupation is one of sordid toil, and altogether a kind of business requiring not so much skill as labour. But as for myself, when I reflect carefully upon its special points one by one, it appears to be far otherwise. For a miner must have the greatest skill in his work, that he may know first of all what mountain or hill, what valley or plain, can be prospected most profitably, or what he should leave alone; moreover, he must understand the veins, stringers and seams in the rocks. Then he must be thoroughly familiar with the many and varied species of earths, juices, gems, stones, marbles, rocks, metals, and compounds In order that the reader should be able to grasp the author’s point of view as to his divisions of the Mineral Kingdom, we introduce here his own statement from De Natura Fossilium, (p. 180). It is also desirable to read the footnote on his theory of ore-deposits on pages to, and the review of De Natura Fossilium given in the Appendix. "The subterranean inanimate bodies are divided into two classes, one of which, because it is a fluid or an exhalation, is called by those names, and the other class is called the minerals. Mineral bodies are solidified from particles of the same substance, such as pure gold, each particle of which is gold, or they are of different substances such as lumps which consist of earth, stone, and metal; these latter may be separated into earth, stone and metal, and therefore the first is not a mixture while the last is called a mixture. The first are again divided into simple and compound minerals. The simple minerals are of four classes, namely earths, solidified juices, stones and metals, while the mineral compounds are of many sorts, as I shall explain later. Earth is a simple mineral body which may be kneaded in the hands when moistened, or from which lute is made when it has been wetted. Earth, properly so called, is found enclosed in veins or veinlets, or frequently on the surface in fields and meadows. This definition is a general one. The harder earth, although moistened by water, does not at once become lute, but does turn into lute if it remains in water for some time. There are many species of earths, some of which have names but others are unnamed. Solidified juices are dry and somewhat hard (subdurus) mineral bodies which when moistened with water do not soften but liquefy instead; or if they do soften, they differ greatly from the earths by their unctuousness (pingue) or by the material of which they consist. Although occasionally they have the hardness of stone, yet because they preserve the form and nature which they had when less hard, they can easily be distinguished from the stones. The juices are divided into ’meagre’ and unctuous (macer et pinguis). The ’meagre’ juices, since they originate from three different substances, are of three species. They are formed from a liquid mixed with earth, or with metal, or with a mineral compound. To the first species belong salt and Nitrum (soda); to the second, chrysocolla, verdigris, iron-rust, and azure; to the third, vitriol, alum, and an acrid juice which is unnamed. The first two of these latter are obtained from pyrites, which is numbered amongst the compound minerals. The third of these comes from Cadmia (in this case the cobalt-zinc-arsenic minerals; the acrid juice is probably zinc sulphate). To the unctuous juices belong these species: sulphur, bitumen, realgar and orpiment. Vitriol and alum, although they are somewhat unctuous yet do not burn, and they differ in their origin from the unctuous juices, for the latter are forced out from the earth by heat, whereas the former are produced when pyrites is softened by moisture. . He must also have a