Gold During the Classical Period
Gold is a subject touched upon by many of the Classical Greek authors, but again the geological references to the precious metal are mostly vague and non-specific. Among these Greek writers we may mention Herodotus (c. 482-425 B.C.), author of History of the Persian Wars; Thucydides (c. 460-400 B.C.), author of History of the Peloponnesian War; Xenophon (c. 430-355 B.C.), historian, man of letters and author of many books and tracts, including De vectigalibus, which is of some interest in the matter of mining; Plato (428-347 B.C.), pupil of Socrates, renowned for his great philosophical works, of which Timae s is of most interest to natural scientists; Aristotle (384-322 B.C.), disciple of Plato, teacher to Alexander the Great, and author of many famous philosophical treatises, of which the Meteorologica is of particular interest in the present context; and Theophrastus (371-288 B.C.) of whom more details will be discussed later.
Little of interest concerning gold deposits can be found in the writings of Thucydides, Xenophon, Plato, and Aristotle, although in the works of the last two there are some speculations on the origin of mineral (gold) veins.
Plato's view of the origin of mineral veins is complex and far less intelligible than other aspects of his philosophy. In the dialogue of the Timaeus a Pythagorean view of the constitution of matter is given in which the minute particles of the four fundamental elements are considered in geometrical terms (e.g., earth a cube, air an octahedron, water an icosahedron, etc.) that undergo changes (transmutations) into one another in definite ratios by resolution into triangles and re-association of these triangles. The metals were evidently considered to be composed of various associations of "fusible" water (liquid), a theory that originated with Thales. Aristotle, likewise, embraced the four-element theory of material things in the Meteorologica and considered that these elements underwent changes (or transmutations) within the earth that were actuated by the deep penetration of the sun's rays. As a result exhalations emanated from the earth, some fiery and dry that produced stones (rocks) and others moist (watery) that gave rise to metals. One can see in these views three fundamental concepts: (1) transmutation of the elements (especially the hope of transmuting the base metals into gold), a possibility that intrigued philosophers and particularly alchemists for centuries and that we now know to be a fact, exemplified by the atomic transmutation of uranium into lead in the earth; (2) the dry and fiery exhalations, which constitute the basis of the magmatic theory of the formation of igneous rocks and certain mineral deposits; and (3) the moist exhalations, or hydrothermal solutions that are considered by many to give rise to most mineral veins.
Herodotus, the "father of history," was born in Asia Minor at Halicarnassus, a Greek city then under Persian rule. He seems to have traveled widely throughout the Persian Empire as well as to Babylon, Egypt, Greece, Libya, Thrace, Macedonia, Scythia, and the Black Sea region. Most of his observations appear to be based on first hand knowledge, although some of his statements are obviously derived from hearsay. None of his observations are detailed, and few give any information of geological interest. In his History of the Persian Wars he describes the great gold deposits near Mt. Pangaeus in Thrace in only one sentence: "Mt. Pangaeus is a great and high mountain abounding in mines of gold and silver".
Theophrastus, the "father of botany," has left us De lapidibus (On stones), an important tract that is a landmark in geological science. Another tract, On Mines, has unfortunately been lost. His works On the History of Plants and On the Causes of Plants are classics in botany.
Theophrastus was Aristotle's favourite pupil and his successor as head of the Lyceum (Peripatos) at Athens. His observations on things mineral are acute, considering the state of science in the last half of the fourth century B.C. He mentions gold in a number of contexts in De lapidibus, an existing fragment of what was evidently a much larger work. Many translations of this fragment exist, the latest in English with an extensive commentary by Caley and Richards (1956).
Theophrastus mentions the gangue stones of gold and silver (pyrite and galena) and writes at some length on the touchstone (probably chert or cherty sediment) and its ability to test what we now refer to as the fineness or carat of gold. Of particular interest, however, is the opening statement in De lapidibus as given in the translation by Caley and Richards (1956, p. 45).
The idea advanced by Theophrastus that gold is made of water probably stems directly from the Platonic view that gold was some kind of dense congealed water, an ancient postulate originating with the "father of Greek philosophy," Thales of Miletus (624-546 B.C.), who argued that the fundamental matrix of all matter was water. Thales was probably led to this conclusion by his observation, and that of others, that mineral matter was commonly precipitated at the orifices of springs. Interpreting broadly we have, therefore, in the statement of Theophrastus the first exposition of the hydrothermal origin of gold deposits.
The Romans mined gold extensively in the metalliferous regions of their empire but, while advancing the art and science of metallurgy, did relatively little beyond simple description with the science of mineral deposits. Diodorus Siculus (first century B.C.), the later Hellenistic historian writing in his Bibliotheca historica at Rome, mentions gold placers and mines in many regions of the Roman Empire and gives lurid accounts of the working of gold and silver mines by slave labour at the time of Julius and Augustus Caesar. The gold placers of Gaul are described, as are those of the Rhine; brief accounts are given of the gold deposits in Arabia and as far as India. Describing the gold deposits of Egypt and neighbouring countries he states (Booth, 1700):
Diodorus in this excerpt and in that quoted in Healy (1978, p. 84) is speaking of gold quartz stockworks in greenstones (amphibolites), or perhaps also in black slates or schists. The reference to white marble (calcite) is probably only partly correct. It would seem that perhaps quartz, the most common gangue in gold veins, was meant.
Strabo (63 B.C.-A.D. 20), another late Hellenistic historian, traveled extensively and made many personal observations on gold deposits throughout the Roman Empire. In his Geographia he mentions briefly the gold placers and mines of Spain and Portugal (Lusitania, Baetica), Macedonia (Paeonia), Italy, Arabia, Egypt, the Caucasus, and India. Writing of the gold of the Caucasus Strabo remarked:
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