De Re Metallica, Translated from the First Latin Edition of 1556

by Georg Agricola

(1) Openings in the earth (canales) were formed by the erosion of subterranean waters.

(2) These ground waters were due (a) to the infiltration of the surface waters, rain, river, and sea water; (b) to the condensation of steam (halitus) arising from the penetration of the surface waters to greater depths,—the production of this halitus being due to subterranean heat, which in his view was in turn due in the main to burning bitumen (a comprehensive genera which embraced coal).

(3) The filling of these canales is composed of "earth," "solidified juices," "stone," metals, and "compounds," all deposited from water and "juices" circulating in the canales. (See also [note 4, page 1]).

"Earth" comprises clay, mud, ochre, marl, and "peculiar earths" generally. The origin of these "earths" was from rocks, due to erosion, transportation, and deposition by water. "Solidified juices" (succi concreti) comprised salt, soda, vitriol, bitumen, etc., being generally those substances which he conceived were soluble in and deposited from water. "Stones" comprised precious, semi-precious, and unusual stones, such as quartz, fluor-spar, etc., as distinguished from country rock; the origin of these he attributed in minor proportion to transportation of fragments of rock, but in the main to deposits from ordinary mineral juice and from "stone juice" (succus lapidescens). Metals comprised the seven traditional metals; the "compounds" comprised the metallic minerals; and both were due to deposition from juices, the compounds being due to a mixture of juices. The "juices" play the most important part in Agricola's theory. Each substance had its own particular juice, and in his theory every substance had a material and an efficient cause, the first being the juice, the second being heat or cold. Owing to the latter the juices fell into two categories—those solidified by heat (i.e., by evaporation, such as salt), and those solidified by cold, (i.e., because metals melt and flow by heat, therefore their solidification was due to cold, and the juice underwent similar treatment). As to the origin of these juices, some were generated by the solution of their own particular substance, but in the [Pg 47]main their origin was due to the combination of "dry things," such as "earth," with water, the mixture being heated, and the resultant metals depended upon the proportions of "earth" and water. In some cases we have been inclined to translate succus (juice) as "solution," but in other cases it embraced substances to which this would not apply, and we feared implying in the text a chemical understanding not warranted prior to the atomic theory. In order to distinguish between earths, (clays, etc.,) the Peripatetic "earth" (a pure element) and the earth (the globe) we have given the two former in quotation marks. There is no doubt some confusion between earth (clays, etc.) and the Peripatetic "earth," as the latter was a pure substance not found in its pristine form in nature; it is, however, difficult to distinguish between the two.

Origin of Canales (De Ortu, p. 35). "I now come to the canales in the earth. These are veins, veinlets, and what are called 'seams in the rocks.' These serve as vessels or receptacles for the material from which minerals (res fossiles) are formed. The term vena is most frequently given to what is contained in the canales, but likewise the same name is applied to the canales themselves. The term vein is borrowed from that used for animals, for just as their veins are distributed through all parts of the body, and just as by means of the veins blood is diffused from the liver throughout the whole body, so also the veins traverse the whole globe, and more particularly the mountainous districts; and water runs and flows through them. With regard to veinlets or stringers and 'seams in the rocks,' which are the thinnest stringers, the following is the mode of their arrangement. Veins in the earth, just like the veins of an animal, have certain veinlets of their own, but in a contrary way. For the larger veins of animals pour blood into the veinlets, while in the earth the humours are usually poured from the veinlets into the larger veins, and rarely flow from the larger into the smaller ones. As for the seams in the rocks (commissurae saxorum) we consider that they are produced by two methods: by the first, which is peculiar to themselves, they are formed at the same time as the rocks, for the heat bakes the refractory material into stone and the non-refractory material similarly heated exhales its humours and is made into 'earth,' generally friable. The other method is common also to veins and veinlets, when water is collected into one place it softens the rock by its liquid nature, and by its weight and pressure breaks and divides it. Now, if the rock is hard, it makes seams in the rocks and veinlets, and if it is not too hard it makes veins. However, if the rocks are not hard, seams and veinlets are created as well as veins. If these do not carry a very large quantity of water, or if they are pressed by a great volume of it, they soon discharge themselves into the nearest veins. The following appears to be the reason why some veinlets or stringers and veins are profundae and others dilatatae. The force of the water crushes and splits the brittle rocks; and when they are broken and split, it forces its way through them and passes on, at one time in a downward direction, making small and large venae profundae, at another time in a lateral direction, in which way venae dilatatae are formed. Now since in each class there are found some which are straight, some inclined, and some crooked, it should be explained that the water makes the vena profunda straight when it runs straight downward, inclined when it runs in an inclined direction; and that it makes a vena dilatata straight when it runs horizontally to the right or left, and in a similar way inclined when it runs in a sloping direction. Stringers and large veins of the profunda sort, extending for considerable lengths, become crooked from two causes. In one case when narrow veins are intersected by wide ones, then the latter bend or drag the former a little. In the other case, when the water runs against very hard rock, being unable to break through, it goes around the nearest way, and the stringers and veins are formed bent and crooked. This last is also the reason we sometimes see crooked small and large venae dilatatae, not unlike the gentle rise and fall of flowing water. Next, venae profundae are wide, either because of abundant water or because the rock is fragile. On the other hand, they are narrow, either because but little water flows and trickles through them, or because the rock is very hard. The venae dilatatae, too, for the same reasons, are either thin or thick. There are other differences, too, in stringers and veins, which I will explain in my work De Re Metallica.... There is also a third kind of vein which, as it cannot be described as a wide vena profunda, nor as a thick vena dilatata, we will call a vena cumulata. These are nothing else than places where some species of mineral is accumulated; sometimes exceeding in depth and also in length and breadth 600 feet; sometimes, or rather generally, not so deep nor so long, nor so wide. These are created when water has broken away the rock for such a length, breadth, and thickness, and has flung aside and ejected the stones and sand from the great cavern which is thus made; and afterward when the mouth is obstructed and closed up, the whole cavern is filled with material from which there is in time produced some one or more minerals. Now I have stated [Pg 48]when discoursing on the origin of subterranean humours, that water erodes away substances inside the earth, just as it does those on the surface, and least of all does it shun minerals; for which reason we may daily see veinlets and veins sometimes filled with air and water, but void and empty of mining products, and sometimes full of these same materials. Even those which are empty of minerals become finally obstructed, and when the rock is broken through at some other point the water gushes out. It is certain that old springs are closed up in some way and new ones opened in others. In the same manner, but much more easily and quickly than in the solid rock, water produces stringers and veins in surface material, whether it be in plains, hills, or mountains. Of this kind are the stringers in the banks of rivers which produce gold, and the veins which produce peculiar earth. So in this manner in the earth are made canales which bear minerals."

Origin of Ground Waters. (De Ortu p. 5). "... Besides rain there is another kind of water by which the interior of the earth is soaked, so that being heated it can continually give off halitus, from which arises a great and abundant force of waters." In description of the modus operandi of halitum, he says (p. 6): "... Halitus rises to the upper parts of the canales, where the congealing cold turns it into water, which by its gravity and weight again runs down to the lowest parts and increases the flow of water if there is any. If any finds its way through a canales dilatata the same thing happens, but it is carried a long way from its place of origin. The first phase of distillation teaches us how this water is produced, for when that which is put into the ampulla is warmed it evaporates (expirare), and this halitus rising into the operculum is converted by cold into water, which drips through the spout. In this way water is being continually created underground." (De Ortu, p. 7): "And so we know from all this that of the waters which are under the earth, some are collected from rain, some arise from halitus (steam), some from river-water, some from sea-water; and we know that the halitum is produced within the earth partly from rain-water, partly from river-water, and partly from sea-water." It would require too much space to set out Agricola's views upon the origin of the subterranean heat which produced this steam. It is an involved theory embracing clashing winds, burning bitumen, coal, etc., and is fully set out in the latter part of Book II, De Ortu et Causis.

Origin of Gangue Minerals. It is necessary to bear in mind that Agricola divided minerals (res fossiles—"Things dug up," see [note 4, p. 1]) into "earths," "solidified juices," "stones," "metals," and "compounds;" and, further, to bear in mind that in his conception of the origin of things generally, he was a disciple of the Peripatetic logic of a "material substance" and an "efficient force," as mentioned above.

As to the origin of "earths," he says (De Ortu, p. 38): "Pure and simple 'earth' originates in the canales in the following way: rain water, which is absorbed by the surface of the earth, first of all penetrates and passes into the inner parts of the earth and mixes with it; next, it is collected from all sides into stringers and veins, where it, and sometimes water of other origin, erodes the 'earth' away,—a great quantity of it if the stringers and veins are in 'earth,' a small quantity if they are in rock. The softer the rock is, the more the water wears away particles by its continual movement. To this class of rock belongs limestone, from which we see chalk, clay, and marl, and other unctuous 'earths' made; also sandstone, from which are made those barren 'earths' which we may see in ravines and on bare rocks. For the rain softens limestone or sandstone and carries particles away with it, and the sediment collects together and forms mud, which afterward solidifies into some kind of 'earth.' In a similar way under the ground the power of water softens the rock and dissolves the coarser fragments of stone. This is clearly shown by the following circumstance, that frequently the powder of rock or marble is found in a soft state and as if partly dissolved. Now, the water carries this mixture into the course of some underground canalis, or dragging it into narrow places, filters away. And in each case the water flows away and a pure and uniform material is left from which 'earth' is made.... Particles of rock, however, are only by force of long time so softened by water as to become similar to particles of 'earth.' It is possible to see 'earth' being made in this way in underground canales in the earth, when drifts or tunnels are driven into the mountains, or when shafts are sunk, for then the canales are laid bare; also it can be seen above ground in ravines, as I have said, or otherwise disclosed. For in both cases it is clear to the eye that they are made out of the 'earth' or rocks, which are often of the same colour. And in just the same way they are made in the springs which the veins discharge. Since all those things which we see with our eyes and which are perceived with our senses, are more clearly understood than if they were learnt by means of reasoning, we deem it sufficient to explain by this argument our view of the origin of 'earth.' In the manner which I have described, 'earths' originate in veins and veinlets, seams in the rocks, springs, ravines, and other openings, therefore all 'earths' are made in this way. [Pg 49]As to those that are found in underground canales which do not appear to have been derived from the earth or rock adjoining, these have undoubtedly been carried by the water for a greater distance from their place of origin; which may be made clear to anyone who seeks their source."

On the origin of solidified juices he states (De Ortu, p. 43): "I will now speak of solidified juices (succi concreti). I give this name to those minerals which are without difficulty resolved into liquids (humore). Some stones and metals, even though they are themselves composed of juices, have been compressed so solidly by the cold that they can only be dissolved with difficulty or not at all.... For juices, as I said above, are either made when dry substances immersed in moisture are cooked by heat, or else they are made when water flows over 'earth,' or when the surrounding moisture corrodes metallic material; or else they are forced out of the ground by the power of heat alone. Therefore, solidified juices originate from liquid juices, which either heat or cold have condensed. But that which heat has dried, fire reduces to dust, and moisture dissolves. Not only does warm or cold water dissolve certain solidified juices, but also humid air; and a juice which the cold has condensed is liquefied by fire and warm water. A salty juice is condensed into salt; a bitter one into soda; an astringent and sharp one into alum or into vitriol. Skilled workmen in a similar way to nature, evaporate water which contains juices of this kind until it is condensed; from salty ones they make salt, from aluminous ones alum, from one which contains vitriol they make vitriol. These workmen imitate nature in condensing liquid juices with heat, but they cannot imitate nature in condensing them by cold. From an astringent juice not only is alum made and vitriol, but also sory, chalcitis, and misy, which appears to be the 'flower' of vitriol, just as melanteria is of sory. (See note on p. [573] for these minerals.) When humour corrodes pyrites so that it is friable, an astringent juice of this kind is obtained."

On the Origin of Stones (De Ortu, p. 50), he states: "It is now necessary to review in a few words what I have said as to all of the material from which stones are made; there is first of all mud; next juice which is solidified by severe cold; then fragments of rock; afterward stone juice (succus lapidescens), which also turns to stone when it comes out into the air; and lastly, everything which has pores capable of receiving a stony juice." As to an "efficient force," he states (p. 54): "But it is now necessary that I should explain my own view, omitting the first and antecedent causes. Thus the [Pg 51]immediate causes are heat and cold; next in some way a stony juice. For we know that stones which water has dissolved, are solidified when dried by heat; and on the contrary, we know that stones which melt by fire, such as quartz, solidify by cold. For solidification and the conditions which are opposite thereto, namely, dissolving and liquefying, spring from causes which are the opposite to each other. Heat, driving the water (humorem) out of a substance, makes it hard; and cold, by withdrawing the air, solidifies the same stone firmly. But if a stony juice, either alone or mixed with water, finds its way into the pores either of plants or animals ... it creates stones.... If stony juice is obtained in certain stony places and flows through the veins, for this reason certain springs, brooks, streams, and lakes, have the power of turning things to stone."