On Minerals

...to have little diversity. There are, however, certain men of the greatest authority in philosophy who, while making a treatise not on all but on certain kinds of stones, have written sufficiently about them.

Those who wrote about stones.

They made mention of such things—men like Hermes Hermes Trismegistus, a legendary Hellenistic figure to whom many alchemical and philosophical works were attributed., Euates original: "euates"; likely referring to King Evax of Arabia, the purported author of a famous medieval lapidary. king of the Arabs, Dioscorides, Aaron, and Joseph—who, by treating only precious original: "sciosis"; likely a transcription error for "pretiosis" (precious). stones, did not treat the general nature of stones. Furthermore, Pliny delivered an insufficient account in his Natural History, not wisely assigning the causes of stones in general; nor is it necessary for us to bring in the opinions of all these men, because the knowledge of the matter is not so hidden that we must collect it from the errors of many. For the nature and "complexions" In medieval science, a "complexion" is the specific balance of the four qualities (hot, cold, moist, dry) in a substance. of stones will be known sufficiently enough once their own matter, their immediate efficient cause, their form, and their own accidental properties are investigated according to the method prescribed in the fourth book of the Meteorology original: "quarto metheoroꝝ"; referring to Aristotle's work on the elements and their interactions..

For we do not intend here to show how any of these might be transmuted into another, or how by the antidote of their medicine—which the alchemists call the "elixir"—they cure their "illnesses" Alchemists often spoke of "sick" metals (like lead) being "cured" into "healthy" gold., or reveal what is hidden, or conversely cover up their manifest traits; but rather to show their mixtures from the elements, and how each is established in its own species. For this reason, we do not care to inquire into the difference between "stone" and "spirit," or "soul" and "body," or "substance" and "accident," about which the alchemists inquire, calling "stone" everything that does not evaporate in fire, and calling the same thing "body" and "substance." However, that which evaporates in the fire, such as sulfur and quicksilver original: "argentum uinū"; literally "living silver" or mercury., and those things from which various colors are made—these they call "spirits," "soul," and "accident," though they also call them "stones." For it belongs to another science to inquire into these things which rely on very hidden reasons and instruments.

However, we will maintain here the same method we have used in individual subjects, dividing the whole work into several books, many treatises, and many chapters. Since a treatise is made here concerning many particular things, we must first recognize the natures of these from signs and effects, and from those arrive at their causes and compositions, because signs and effects are more manifest to us. However, in the study of universal nature—of which we made mention in all the preceding books—one had to proceed in reverse: namely, from the cause to the effects, and to the powers and signs, because in such things the common and general aspects are more evident and manifest to us, as determined in the first book of the Physics. Indeed, we have sufficiently shown the order of this book in relation to the following books on nature at the end of our book on Meteorology, where we stated which things must be discussed first and which later. For since the kinds of stones and metals are "homeomerous" omiomeraA term from Aristotelian physics meaning "uniform parts." For example, a piece of stone is made of smaller pieces that are also stone, unlike a plant (anomiomera) which has distinct parts like roots and leaves. more so than plants, in which one finds a diversity of parts such as root, leaf, flower, and fruit—and "homeomerous" things are by nature prior to "anhomeomerous" heterogeneous or non-uniform things—it follows that stones and other minerals must be treated before the bodies of living things.

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Chapter two: on the matter of stones.

Twofold [matter]

In beginning, therefore, to treat the nature of stones in general, we say that the matter of every stone is either a species of earth or a species of water. For one of these elements prevails in stones; and even in those in which a certain species of water seems to dominate, there is also something of earth dominating the matter at the same time. A sign of this is that almost all kinds of stones sink under water—the kinds of stones which we said abound in the matter of "earth" in the science of On the Heavens and the World. For if the "higher" elements air and fire, which are lighter were dominant in them, they would float a little upon the water. As it is, however, no kind of stone floats unless it be spongy or burnt, and made spongy and porous through burning, like pumice and the stone vomited by hot springs or the fire of a volcano; even if these are reduced to powder, the powder itself sinks under water.

Furthermore, if there were not an "earthy" moisture mixed in to give a boundary The concept that water needs earth to give it a solid "limit" or shape. even in transparent stones, they would not sink under water—stones like crystal and beryl—just as ice and other things in which the water is pure or overabundant do not sink. Furthermore, all stones that are generated in the kidneys and bladders of animals are generated from a viscous, thick, and earthy moisture. It is necessary, therefore, that such be the matter of stones.

Specifically speaking of those stones in which the matter is earth, it can easily be seen that in these, earth is not the only matter, for earth alone would not hold together into the solidity of a stone. For we say that the cause of "continuation" cohesion and mixture is moisture; this, by its subtlety, makes one part of the earth flow toward another, and this is the cause of the good mixing of the parts of the matter. If, however, this moisture were not well-infused everywhere into the earthy parts, and if it were not "retentive" able to hold things together and evaporated during the coagulation of the stone, then there would remain an earthy dust without cohesion. For this reason, it is necessary that it be viscous and gluey, so that its parts might entwine with the earthy parts like the links of chains. Thus the dry earth retains the moisture, and the watery moisture existing within the dry matter creates the cohesion.

And Avicenna Ibn Sina, the Persian polymath whose works on geology and medicine were central to medieval university education. testifies to this when he says that pure earth does not become stone, because earth, by its dryness, does not create cohesion but rather fragmentation; for the prevailing dryness in it does not allow "agglutination" sticking together to occur. The same philosopher gives the reason: that sometimes mud is dried and becomes something halfway between stone and mud, and then in the space of time it becomes stone. He says again that the mud most fit to be transmuted into stone is "unctuous" oily or greasy; for that which is not so is fragmentary or easily crumbled into powder because of the easy separability of moisture from it. A sign of this is that in stones themselves, veins of earth frequently remain, which is hard, dry earth that becomes powder when compressed or struck. The cause of this is nothing other than that its moisture, not being sufficiently unctuous and viscous, evaporated from it during the stone's coagulation.