On Minerals

...lation: and therefore it remained a hard earth, capable of being crumbled because of the power of coagulation In medieval science, "coagulation" refers to the process by which a liquid or soft substance hardens into a solid. of the surrounding stone. There is also another sign of this: because when stones are not generated continuously, but in the manner of planks meaning in layers or strata so that one is generated on top of another and not continuously united, such earth interposed between them suffers crumbling under pressure or striking; and it is hard: the cause of which is that which we stated above. Furthermore, there is a viscous and oily moisture which is the binding agent for the matter of the stone: this is signified by the fact that the animals which they call "tortoises" original: "testudines"; here referring to fossilized shellfish or ammonites, whose shells were often thought to grow within the rock itself. are very frequently generated with their shells inside stones. This is most common in stones found in small pieces which have many openings containing the shapes of the shells of these "tortoises," which some call "lunar" stones. The cause of this is the moisture which evaporated to that place, and being retained by the surrounding material, it was rolled up within itself; first becoming firm on the outside, and being rotated within itself, it received a "vital spirit," just as we say in the fourth book of the Meteorology Aristotle's Meteorology, which Albertus uses as his primary scientific framework.. This, therefore, is the general matter of those stones that are neither transparent nor sparkling; however, they vary in different ways, as will appear in what follows.

Chapter Three: Concerning the transparency of stones

according to more and less.

The matter of transparent stones

Of stones that are transparent to a greater or lesser degree, such as those called gems, it can be said in general that their common matter is an impure water. For those stones are a kind of glass produced by the work of nature; because of this, they are even finer in their mixture and clearer in their transparency than the glasses made by art, because although art imitates nature, it cannot fully reach the perfection of nature's work. A sign of what we have said—namely, that water affected by dry heat or cold is the common matter of these stones—is that glasses are made from this kind of moisture which is melted by the strongest fire from various ashes, whether of lead, or fern, or iron, or some other substance. That this moisture is indeed water is shown by the fact that it is coagulated by cold and is melted and liquefied by vehement dry heat. Moreover, that it has been affected by parched, earthy dryness is proved by the fact that it does not liquefy except from ash through a most vehement roasting, just as is shown visibly in the "divine art" A common medieval term for alchemy. and in the art of glassmaking, which is subordinate to alchemy. For a subtle vapor in the earth or in a stone is sometimes contained by the surrounding material, and being rolled up within itself, it becomes moist, just as happens in a covered hot pot in which there is some water. And when the moisture is thus vehemently affected by the dry, the dry and constant power within it coagulates into stone. But here we must not speak of the manner of the generation of stones, but rather of the matter of stones in general; whether their coagulation occurs by cold or heat will be shown later. That water is the matter of such stone is also shown because in certain places where there is a strong power for generating stones,

water descending as rain, drop by drop or otherwise poured out, hardens into stone. For as it descends, it is first affected by the terrestrial dryness from the nature and operation of the place, and thus it is made into the proper matter of stone. This is also shown by the multitude of transparent parts found in such stones. Since the transparency of air and fire are not indestructible, it must necessarily be that this transparency comes from the transparency of water; therefore, their proper matter will be of the nature of water. As for what some of the ancients say when showing the matter of stones—that something descends from running water which resides at the bottom, and this becomes stone—I do not approve of this, because that which descends from water is a terrestrial substance. Therefore, those stones which are generated from this often do not take as their matter water affected by a terrestrial power, but rather earth that has been affected by the powers of water. A sign of this is that such stones are frequently not transparent, but are "terminated" meaning opaque or having definite boundaries that light cannot penetrate and are said to be not "cuttable" but rather "crumbled," and are called flints by the common people. This is especially testified to by crystal and beryl, which have taken on almost the exact form of frozen water; concerning which Aristotle said that they are made from water when the heat is entirely removed. Just as we said that the matter of the stones mentioned in the previous chapter was earth (not simple earth, but affected by an oily, viscous moisture), so now it must be understood of these that simple aqueous moisture cannot be the matter of transparent stones. For as we have shown elsewhere, such moisture does not stand firm through "decoction" long-term heating or boiling, nor is it coagulated by dry heat, nor frozen by cold in any way that would last. Therefore, it is necessary that it be mixed with a very subtle terrestrial influence, and furthermore be most strongly affected by terrestrial dryness, so that its power now, as it were, takes hold of all parts of such moisture, yet without having yet transmuted the substance of such moisture into earth. For in every transmutation of the elements, such an "affection" a change in qualities like heat or moisture precedes the transmutation of the substance; namely, that the power of the transmuting element takes hold of the whole, and the parts of the transmuted element are shaped within it before the transmutation of the substance occurs. And if they are thus mixed into some "elementated" thing a compound substance made of elements, that thing will have the matter of one element and the powers of another element; and this is the highest ingenuity of the alchemists. Hermes teaches this in his Secret of Secrets Referring to the "Tabula Smaragdina" or Emerald Tablet, a foundation of alchemical philosophy. through metaphorical words:

Hermes

saying, "The stone rises gently with great ingenuity from the earth to heaven, and again descends from heaven to earth... its nurse is the earth, and the wind carried it in its belly." For intending to teach the works of alchemy, he says it "ascends to heaven" when, through roasting and calcination The process of heating a substance to high temperatures to reduce it to a powder or change its properties., it takes on the properties of fire. For the alchemists call calcination the burning and roasting that reduces matter to a powder; which matter "descends again from heaven to earth" when it takes on the powers of earth through "inhumation" The alchemical process of "burial," placing the substance in the earth or a dark, moist place to mature.; for then, through inhumation, that which was previously through calcin...