Albertus [Magnus] ... debased the doctrine of Aristotle with the itch of the chemists flowing with the bloody flux of quicksilver and the stench of sulphur.

Enhydros is a variety of geode. The name comes from the water it contains. It is always round, smooth, and very white but will sway back and forth when moved. Inside it is a liquid just as in an egg, as Pliny, our Albertus, and others believed, and it may even drip water. Liquid bitumen, sometimes with a pleasant odor, is found enclosed in rock just as in a vase.

I realize that Galen called an earth which contained metallic particles a mixed earth when actually it is a composite earth. But it behooves one who teaches others to give exact names to everything.

Mineral substances vary greatly in color, transparency, luster, brilliance, odor, taste, and other properties which are shown by their strength and weakness, shape, and form. They do not have the variety of origins that we find not only in living matter but also in original matter. Moreover they have not been classified like the latter on the basis of the place where they pass their life since mineral substances lack life and with rare exceptions are found only within the earth. They do not have the differences in characters and actions which nature has given to living things alone. Great differences are not the essential features of minerals as they are of living and original matter.

There are many arts and sciences of which a miner should not be ignorant. First there is Philosophy, that he may discern the origin, cause, and nature of subterranean things; for then he will be able to dig out the veins easily and advantageously, and to obtain more abundant results from his mining. Secondly there is Medicine, that he may be able to look after his diggers and other workman ... Thirdly follows astronomy, that he may know the divisions of the heavens and from them judge the directions of the veins. Fourthly, there is the science of Surveying that he may be able to estimate how deep a shaft should be sunk … Fifthly, his knowledge of Arithmetical Science should be such that he may calculate the cost to be incurred in the machinery and the working of the mine. Sixthly, his learning must comprise Architecture, that he himself may construct the various machines and timber work required underground … Next, he must have knowledge of Drawing, that he can draw plans of his machinery. Lastly, there is the Law, especially that dealing with metals, that he may claim his own rights, that he may undertake the duty of giving others his opinion on legal matters, that he may not take another man’s property and so make trouble for himself, and that he may fulfil his obligations to others according to the law.

There are reported to be six species of metals, namely, gold, silver, iron, copper, tin, and lead. Actually there are more. Mercury is a metal although we differ on this point with the chemists. Plumbum cinereum (gray lead) which we call bisemutum was unknown to the older Greek writers. On the other hand, Ammonius writes correctly many metals are unknown to us, as well as many plants and animals.