Rich as the auriferous drifts of the deep alluvial deposits are frequently found to be, they must be within definite limits, having been deposited by currents and the continuous action of waves not far from the localities where the gold was originally formed. But the alluvial gold of Victoria and New South Wales is not confined to drifts and gutters. There are hundreds, probably thousands, of square miles, where the clay, earth, and sand are impregnated with gold in sufficient quantities to pay well for washing. Besides these deposits of incalculable wealth, there are vast reserves of gold locked up in the great mountain ranges both of Victoria and New South Wales, the hidden wealth of which will eventually be brought to light by systematic mining.
As even the richest auriferous drift would be comparatively worthless without the assistance of water, the diversion of a running stream through a ‘placer’ is often one of the most laborious undertakings of the gold-digger.
Pliny speaks of ‘the bringing of the rivers from the mountains, in many instances for a hundred miles, for the purpose of washing the débris,’ and this method of hydraulic mining is now carried on in California on a stupendous scale. Thus, north of Mariposa County, the thick deposits, often semi-indurated, are now washed down by vast streams of water (thrown by the pressure of a column of water of 150 feet), that do the work of running off the earth and gravel and gathering the gold in an incredibly short time.
The ores of auriferous quartz are treated in a different way from the alluvial débris. After having been crushed and pulverised by powerful machinery, the finely powdered quartz is then treated with mercury, a method well known to the ancients. This metal dissolves out the gold, producing an amalgam, which, by straining and distillation, yields the gold.
CHAPTER XXV.
SILVER.
Its ancient Discovery—Its uses among the luxurious Romans—The Mines of Laurium—Silver Mines of Bohemia, Saxony, and Hungary—Colossal Nuggets—Silver Ores—Silver Production of Europe—Mexican Silver Mines—The Veta Madre of Guanaxuato—The Conde de la Valenciana—Zacatecas and Catorce—Adventures of a Steam-engine—La Bolsa de Dios Padre—The Conde de la Regla—Ill-fated English Companies—Indian Carriers—The Dressing of Silver Ores—Amalgamating Process—Enormous Production of Mexican Mines—Potosi—Cerro de Pasco—Gualgayoc—The Mine of Salcedo—Hostility of the Indians—The Monk’s Rosary—Chilian Mines—The Comstock Lode.
Like that of gold, the first discovery of silver precedes the historic times, and must no doubt be sought for in the remotest antiquity; for as it is not seldom found in a native state, its brilliancy could not fail to attract attention at a very early age. Veins of silver ore, moreover, not seldom crop out on the surface, a circumstance which likewise greatly facilitated the accidental discovery of the metal. Thus Diodorus relates that streams of melted silver flowed out of the calcined soil where some shepherds had set fire to a forest in the Pyrenees. The cunning Phœnician merchants, who were trading in the neighbourhood, bought the metal for a trifle from the natives, who, ignorant of its value, gladly exchanged it for some worthless trinkets.
Our earliest annals show us silver in common use among the more polished nations of antiquity, both for ornamental purposes and as a means of exchange. When we read in the Bible that Abraham weighed to Ephron the Hittite ‘four hundred shekels of silver, current money with the merchant’ for the purchase of the field of Machpelah, where Sarah was buried, we cannot possibly doubt that, long before the patriarch’s time, great quantities of silver must have circulated among the traders of the East, and that even then it belonged to the discoveries of ancient days.
Homer describes the shields and helmets of his heroes as inlaid with silver, and in Northern Asia silver ornaments have been found in the tumuli of the Tschudi, a mysterious people who have left no vestiges of their existence save their tombs.
The Babylonian, Assyrian, and Persian monarchs imposed large tributes of silver on the conquered nations of Asia, and at a later period the treasures thus amassed by a long line of despots came into the possession of Alexander the Great, and finally of the Romans, who absorbed all the riches of Carthage and the East. In the reign of Augustus, the tables of the wealthy senators groaned under silver dishes weighing from one hundred to five hundred pounds; silver statues of their ancestors decorated their apartments, and they not seldom performed their luxurious ablutions in baths of silver. Mirrors of this metal were in frequent use among a people to whom the art of applying a lustrous amalgam to the back of a plate of glass was unknown.