The gold found by excavating with galleries does not require to be melted, but is pure gold at once. In these excavations, too, it is found in lumps, as also in the shafts which are sunk, sometimes exceeding ten pounds even. The names given to these lumps are “palagæ,” and “palacurnæ,”[898] while the gold found in small grains is known as “baluce.” The ulex that is used for the above purpose is dried and burnt, after which the ashes of it are washed upon a bed of grassy turf, in order that the gold may be deposited thereupon.
Asturia, Gallæcia, and Lusitania furnish in this manner, yearly, according to some authorities, twenty thousand pounds’ weight of gold, the produce of Asturia forming the major part. Indeed, there is no part of the world that for centuries has maintained such a continuous fertility in gold. I have already[899] mentioned that by an ancient decree of the senate, the soil of Italy has been protected from these researches; otherwise, there would be no land more fertile in metals. There is extant also a censorial law relative to the gold mines of Victumulæ, in the territory of Vercellæ,[900] by which the farmers of the revenue were forbidden to employ more than five thousand men at the works.
There is also one other method of procuring gold; by making it from orpiment,[901] a mineral dug from the surface of the earth in Syria, and much used by painters. It is just the colour of gold, but brittle, like mirror-stone,[902] in fact. This substance greatly excited the hopes of the Emperor Caius,[903] a prince who was most greedy for gold. He accordingly had a large quantity of it melted, and really did obtain some excellent gold;[904] but then the proportion was so extremely small, that he found himself a loser thereby. Such was the result of an experiment prompted solely by avarice: and this too, although the price of the orpiment itself was no more than four denarii per pound. Since his time, the experiment has never been repeated.
In all[905] gold ore there is some silver, in varying proportions; a tenth part in some instances, an eighth in others. In one mine, and that only, the one known as the mine of Albucrara, in Gallæcia,[906] the proportion of silver is but one thirty-sixth: hence it is that the ore of this mine is so much more valuable than that of others. Whenever the proportion of silver is one-fifth, the ore is known also by the name of “electrum;”[907] grains, too, of this metal are often found in the gold known as “canaliense.”[908] An artificial[909] electrum, too, is made, by mixing silver with gold. If the proportion of silver exceeds one-fifth, the metal offers no resistance on the anvil.