ORIGIN OF THE ORES. 
223 
to be definitely established. It is certain that sodium was extracted and that the 
waters must have been greatly enriched in this metal during their journey through 
the rocks. The alkalies were present as chlorides, carbonates, sulphates, and sul¬ 
phides, as well as their several ions. 
TELLURIUM AND GOLD. 
% 
If it be assumed that the ores shipped average $40 per ton, it should be remem¬ 
bered that the actual ore, which in the fissure deposits of Cripple Creek is formed 
only in the narrow seams and cracks of the lode, constitutes less than 10 per cent, 
perhaps only 5 per cent, of the total material extracted, and that it would thus 
have a value of upward of $400 per ton. For present purposes we may assume 
that this material consists of 60 per cent quartz, 20 per cent dolomite, and 20 per 
cent fluorite, to which should be added 0.1 per cent gold and 0.2 per cent tellurium, 
besides small amounts of iron, copper, lead, zinc, and molybdenum, each of which 
would on the average rarely exceed a fraction of 1 per cent. A water depositing 
such a product was surely of a most unusual character, compared to ordinary 
surface waters, and even compared to those which deposited the normal gold-quartz 
veins, in which the tenor of the filling is rarely higher than 1 ounce per ton. 
Concerning the reactions by which the tellurides were deposited or the con¬ 
dition in which they existed in the solution our information is scant. The associa¬ 
tion of tellurides with fluorite is an interesting but probably not at all essential 
point, because, as Penrose has already emphasized, there is no quantitative relation 
between the two minerals. In some of the richest ores fluorite may be extremely 
scarce. In his great monograph on metamorphism, Van Hise“ devotes consider¬ 
able space to a discussion of the tellurides. He says: 
At first thought one might conclude that the gold, silver, and tellurium were transported as tellurides 
and deposited as such without chemical change, but the recent work of Lenher and Halit is decidedly against 
this view. They have found no solvent whatever for tellurides of gold without breaking up these compounds 
and producing salts of tellurium, the gold usually being left in the metallic form. Moreover, as has already 
been noted, they have shown that metallic tellurium and seven of the more common mineral tellurides of 
gold and silver rapidly reduce gold from its solutions, forming metallic gold, the tellurium at the same time 
going into solution. Further, they have proved that the presence of any of the soluble tellurides, including 
hydrogen tellurides, is sufficient not only to throw the gold out of solution, but to prevent it from getting 
into solution. Other soluble salts, where tellurium acts as an acid, are the tellurites and tellurates. Tellurous 
oxide or acid is also sparingly soluble. All of these compounds, like tellurides, precipitate gold from its solu¬ 
tions in a metallic form, not as telluride. From the foregoing it appears that if tellurium compounds in which 
tellurium is a part of the acid are essential for the formation of the tellurides of gold, these tellurium salts and 
the gold have come into the trunk channel from separate sources. They could not have traveled together; 
else the gold would have been thrown from the solutions before reaching the trunk channels. 
* ****** 
It may be that the key to the problem of the deposition of the tellurides lies in their association with 
sulphides. We have already seen that telluric salts of the type of TeCl 4 may travel with gold in solutions. 
It has already been pointed out that gold, in most cases, probably also travels as a chloride, and thus solutions 
of auric chloride and telluric chloride, may together enter trunk channels which contain sulphides. In such 
trunk channels the reaction of the sulphides might reduce both the gold and the tellurium simultaneously 
and thus produce tellurides of gold; or, by the reaction of the sulphides upon the telluric salts, these may 
a Mon. U. S. Geol. Survey, vol. 47, 1S04, pp. 1119-1125, especially pp. 1120, 112:. 
6 Lenher, Victor, Naturally occuring telluride of gold: Jour. Am. Chem. Soc., vol. 24, 1902, pp. 35.5-360. Hall, R. D., 
and Lenher, Victor, Action of tellurium and selenium on gold and silver salts: Idem, pp. 918-927. 
