SPRING QUARTER, 2006
Department of History
University of California, Irvine
Instructor: Dr. Barbara J. Becker
Week 1. Soul excerpts from
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Of the substances formed in the ground, some are made of water and some of earth. The metals obtained by mining, such as silver, gold, and so on, come from water; from earth come stones, including the precious kinds, and also the types of earth that are unusual because of their color, smoothness, density, or any other quality. As the metals have been discussed in another place, let us now speak about the stones.
In general we must consider that all of them are formed from some pure and homogeneous matter as a result of a conflux or percolation, or because the matter has been separated in some other way, as has been explained above. For perhaps some are produced in one of these ways, and some in the other way, and others in a different manner. Hence they gain their smoothness, density, brightness, transparency, and other such qualities, and the more uniform and pure each of them is, the more do these qualities appear. In general, the qualities are produced according to the accuracy with which the stones are formed and solidified.
Some things are solidified through heat, others through cold. And probably there is nothing to prevent some kinds of stones being formed by either of these two methods, although it would seem that all the types of earth are produced by fire, since things become solid or melt as a result of opposite forces. There are more peculiarities in stones; for most of the differences in the types of earth concern color, tenacity, smoothness, density, and so on, but in other respects the differences are rare.
Stones, however, have these differences and in addition there are others that depend on their power of acting on other substances, or of being subject or not subject to such action. For some can be melted and others cannot, some can be burnt and others cannot, and there are other differences of this kind. And some show a number of differences in the actual process of being set on fire and burnt, and some, like the smaragdos [emerald] can make the color of water the same as their own, whereas others can turn what is placed on them entirely into stone; some have the power of attraction and others can test gold and silver, such as the stone called the Heraclean [lodestone; magnetite] and the one called the Lydian [touchstone; a black stone used to test precious metals: the metal in question is drawn across the touchstone, leaving a mark which could be examined to assay the metal's quality and purity].
But the greatest and most wonderful power, if this is true, is that of stones which give birth to young. But the power of those used in manual work is better known and is found in more varieties. For some can be carved, or turned on a lathe, or sawn; there are some on which an iron tool cannot operate at all, and others on which it works badly and with difficulty. And there are several other differences in addition to these....
Coral, which is like a stone, is red in color and rounded like a root, and it grows in the sea. And in a way the petrified Indian reed [bamboo?] is not very different in its nature from coral. But this is a subject for another inquiry....
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