History of the big bonanza

by Dan De Quille

On the 1500-foot level the bonanza extends into the Consolidated Virginia ground over three hundred feet. How much further it may extend in that direction on the levels below remains to be ascertained. The “chimneys” of ore, or bonanzas, everywhere on the Comstock have had a southward inclination, in addition to dipping eastward with the vein. The dip of the vein is to the east, at an angle of from 30 to 45 degrees, while the inclination of the chimneys of ore to the southward is at an angle of from 60 to 75 degrees. This southern dip or inclination will, as many suppose, carry the southern part of the bonanza into the Best & Belcher ground at a certain depth. To reach the Best & Belcher the ore must pass entirely through the lower-levels of the Consolidated Virginia mine. At the depth of 1700 feet a drift has been run southward into the Best & Belcher ground from the Gould & Curry, and the work of cross-cutting commenced. Even at this depth it is not unlikely that they will tap the bonanza.

Two hundred feet north of the bonanza we have been examining (the stope at cross-cut No. 3), another stope has been raised (on cross-cut No. 1) toward the 1400-foot level, and here large quantities of rich ore are being extracted. Cross-cut No. 2, about half way between the two stopes mentioned, shows the bonanza to be three hundred feet in width, all of this great distance being a mass of rich ore, and ore that can be sent to the mills without assorting. Think of a mass of silver-ore over eighteen rods in width! In many places a vein of ore three feet in thickness is considered large, and in California veins of gold-bearing quartz that are only from one to six inches in thickness are profitably worked. Compared with such deposits the bonanza is not a vein at all but a field, a district of ore!

No such breadth of silver-ore has ever before been found in any mine in the world. The silver-bearing veins of Europe are but a few feet in width, and to speak to a German miner of a mine in which the breadth of ore was measured by rods would cause him to suppose that he was talking with a crazy man. Even in the richest mines of Mexico and South America they have never had any such astounding width of bonanza. Then they have always been able to keep up their ground with single timbers—posts and caps—which they could not have done with bodies of ore more than a few feet in width. On the Comstock hardly one bonanza has been found that could have been worked by timbering with posts and caps. In order to work the ore-bodies of the Comstock it became necessary to invent a new and special system of timbering.

In this broadest part of the bonanza we find at work a great number of miners, but they are so distributed that we see but a few in any one spot. They work on separate floors, and floor above floor they are digging down the ore. The pyramids of timbers rise to the height of fifty or seventy-five feet, and, as all the heated air of the level ascends to the highest point, it is very hot where the upper gangs of men are at work. In addition to the natural heat of the mine, coming from the heated rock and hot water, the flame of the hundreds of candles and lamps does much to heat the limited atmosphere of the level; besides, the air is vitiated by the breathing of so many men. Candles and lungs rapidly consume the oxygen contained in a given amount of air. In order that the miners in the upper part of the stope may work in something approaching to comfort, there are here small blowers which send up to them through tin tubes a supply of fresh air. Without fresh air from the surface men can no more work in a mine than they could work under the sea in a diving-bell, were no air sent them. These blowers are all driven by small engines run by compressed air, there being in constant operation on the surface two powerful air-compressors that force air down through mains, under a great pressure, for the supplying of the Burleigh drills and the engines in various places on the several levels of the mine.

Besides the air-engines that run the blowers in this part of the mine there are other engines, driven by compressed air, that hoist all of the timbers to the men working in the upper part of the stopes. Nothing is done by hand that can be done by machinery. As the miners always work upwards in extracting ore, there is little heavy handling of the ore itself after it is dug out of the breasts. It is sent down to the floor of the level in chutes, which land it in bins, from which it is drawn out through gates into the cars which convey it to the main shaft, up which it is hoisted to the surface.

In the centre of this part of the bonanza we have on each side of us a width of over nine rods of silver-ore that will mill from $100 to $250, and in many parts of which ore is found that assays five or six hundred dollars. Not only have we this mass of ore on all sides of us, but it also extends to a great height above. On the 1,400, 1,300, 1,200, and the 1,167-foot levels men are at work as we see them here. From the level last named, when the ore was first found, in 1873, they have followed it up to the 1000-foot level and even above. Fifty feet below the level on which we stand, or on the 1550-foot level, a long drift has been run through rich ore toward the Ophir mine, and from this drift a number of cross-cuts have been run into the bonanza. On this 1550-foot level a winze has been sunk to the depth of over two hundred feet, all the way in excellent ore. This shows the bonanza to extend, at least, to a depth of over 1,750 feet. Near the stope on cross-cut No. 1, about the California line, is seen some of the richest ore found in the great bonanza. At this point comes in what is called a “horse,” which is a huge mass of propylite (generally spoken of as porphyry in the mines), which tumbled into the vein from the upper or hanging wall at the time of the formation of the fissure. This “horse” crowds the ore into a smaller space, and the ore-body is here only about twelve rods in width, but the greater part of it is immensely rich—such as will yield from $300 to $600 per ton.

Here are frequently found deposits of stephanite, or silver in the form of crystals. This is almost pure silver. In the places where the stephanite occurs there are frequently found nests of pure, malleable silver in the shape of flattened wires that look as though they had been pulled in two, and in springing back after breaking had coiled up against the pieces of ore on which they are found. Some of these wires have the lustre of metallic silver, but the greater part are blackened as though by the fumes of sulphur. Some of the smaller and finer wires on being unrolled and straightened out are found to be a foot or more in length, and often have several branches, when they somewhat resemble sea-moss, or some similar vegetable production. The old Mexican mine was particularly rich in specimens of this kind. In that mine they were found in a kind of yellow clay in the crevices occurring in the mass of the ore.

Free gold, in glittering spangles, is also very frequently found in the places where the rich deposits of black sulphuret of silver, and native silver occur. A large percentage of the value of the ores of all the mines on the Comstock is in gold. In many instances the bullion extracted is fifty per cent. gold. In that part of the bonanza through which passes the line between the California and the Consolidated Virginia Companies, it is an easy matter to find ore that assays from $1,000 to $5,000 or $10,000 per ton, but this is, of course, only in places where the strength of the vein appears to have concentrated.

At the time that the first cross-cut (No. 1) was run through this part of the bonanza, at a point about fourteen feet south of the California line, a chamber about ten feet square was opened (at a point marked “winze down to 1550” on the map) the walls of which were a solid mass of black sulphuret ore flecked with native silver, while the roof was filled with stephanite, or silver in the form of crystals. This was one of the richest spots found in that part of the bonanza, and the masses of ore taken out were almost pure silver. Many magnificent specimens for cabinets were taken from this chamber and parts of the mine adjoining, some of them little else but stephanite and wires of native silver. The whole cross-cut through this part of the mine showed an average assay of $600 per ton. Bottom, top, sides were all the same. Look where you might you saw but a solid mass of black sulphuret ore mingled with the pale green ore containing chloride of silver.

Two mining superintendents were one day discussing the bonanza, when one of them said to his brother silver-hunter: “Supposing the Almighty to have given you full power and authority to make such a body of ore as you pleased, could you have made a better than this?”