Note 4 — BOOK I.

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 43 to 53, 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.

[Pg 2] "Stone is a dry and hard mineral body which may either be softened by remaining for a long time in water and be reduced to powder by a fierce fire; or else it does not soften with water but the heat of a great fire liquefies it. To the first species belong those stones which have been solidified by heat, to the second those solidified (literally 'congealed') by cold. These two species of stones are constituted from their own material. However, writers on natural subjects who take into consideration the quantity and quality of stones and their value, divide them into four classes. The first of these has no name of its own but is called in common parlance 'stone': to this class belong loadstone, jasper (or bloodstone) and Aetites (geodes?). The second class comprises hard stones, either pellucid or ornamental, with very beautiful and varied colours which sparkle marvellously; they are called gems. The third comprises stones which are only brilliant after they have been polished, and are usually called marble. The fourth are called rocks; they are found in quarries, from which they are hewn out for use in building, and they are cut into various shapes. None of the rocks show colour or take a polish. Few of the stones sparkle; fewer still are transparent. Marble is sometimes only distinguishable from opaque gems by its volume; rock is always distinguishable from stones properly so-called by its volume. Both the stones and the gems are usually to be found in veins and veinlets which traverse the rocks and marble. These four classes, as I have already stated, are divided into many species, which I will explain in their proper place.

"Metal is a mineral body, by nature either liquid or somewhat hard. The latter may be melted by the heat of the fire, but when it has cooled down again and lost all heat, it becomes hard again and resumes its proper form. In this respect it differs from the stone which melts in the fire, for although the latter regain its hardness, yet it loses its pristine form and properties. Traditionally there are six different kinds of metals, namely gold, silver, copper, iron, tin and lead. There are really others, for quicksilver is a metal, although the Alchemists disagree with us on this subject, and bismuth is also. The ancient Greek writers seem to have been ignorant of bismuth, wherefore Ammonius rightly states that there are many species of metals, animals, and plants which are unknown to us. Stibium when smelted in the crucible and refined has as much right to be regarded as a proper metal as is accorded to lead by writers. If when smelted, a certain portion be added to tin, a bookseller's alloy is produced from which the type is made that is used by those who print books on paper. Each metal has its own form which it preserves when separated from those metals which were mixed with it. Therefore neither electrum nor Stannum is of itself a real metal, but rather an alloy of two metals. Electrum is an alloy of gold and silver, Stannum of lead and silver (see note 33, p. 473). And yet if silver be parted from the electrum, then gold remains and not electrum; if silver be taken away from Stannum, then lead remains and not Stannum. Whether brass, however, is found as a native metal or not, cannot be ascertained with any surety. We only know of the artificial brass, which consists of copper tinted with the colour of the mineral calamine. And yet if any should be dug up, it would be a proper metal. Black and white copper seem to be different from the red kind. Metal, therefore, is by nature either solid, as I have stated, or fluid, as in the unique case of quicksilver. But enough now concerning the simple kinds.

"I will now speak of the compounds which are composed of the simple minerals cemented together by nature, and under the word 'compound' I now discuss those mineral bodies which consist of two or three simple minerals. They are likewise mineral substances, but so thoroughly mixed and alloyed that even in the smallest part there is not wanting any substance that is contained in the whole. Only by the force of the fire is it possible to separate one of the simple mineral substances from another; either the third from the other two, or two from the third, if there were three in the same compound. These two, three or more bodies are so completely mixed into one new species that the pristine form of none of these is recognisable.

"The 'mixed' minerals, which are composed of those same simple minerals, differ from the 'compounds,' in that the simple minerals each preserves its own form so that they can be separated one from the other not only by fire but sometimes by water and sometimes by hand. As these two classes differ so greatly from one another I usually use two different words in order to distinguish one from the other. I am well aware that [Pg 3]Galen calls the metallic earth a compound which is really a mixture, but he who wishes to instruct others should bestow upon each separate thing a definite name."

For convenience of reference we may reduce the above to a diagram as follows:

1. Fluids and gases.

2. Mineral bodiesA. Homogenous bodies(a) Simple mineralsEarths

Solidified juices

Stones

Metals

(b) Compound mineralsBeing heterogeneous mixtures of (a)

B. Mixtures.Being homogenous mixtures of (a)