The Monument mine, owned by the Monument Gold Mining Company, of Colorado Springs, capital, $300,000, adjoins the Dillon on the north. It, too, is a small mine, the underground workings being confined to the narrow and very irregular area in the Monument claim that is not covered by older locations.
It is almost completely inclosed by the Granite claim on the west, the Portland property on the north and east, and the Dillon claim on the south.
The company was incorporated in 1898 and has operated the mine under the leasing system.
Access to the mine is through a vertical shaft about 550 feet in depth. There are six levels at various distances apart.
As in the Dillon, there are a number of narrow sheeted zones of no great width or persistency. The Monument lode lies west of the shaft and runs nearly due north and south. It dips about 80° E.
About 150 feet north of the shaft it is joined on the east side by the Kurtz vein, which strikes northwest and dips about 70° SW. Neither lode has been followed for more than a few feet north of the junction.
About 200 feet south-southwest from the shaft, near the northwest corner of the Dillon claim, is the Par Value vein, which strikes N. 8° W. and intersects the Stonehouse lode.
In general there are in the mine two intersecting sets of fissure zones, one striking a few degrees west of north, represented by the Monument and Par Value lodes, and one striking nearly northwest, represented by the Kurtz and Stonehouse lodes. The Kurtz lode has not been identified below the 285-foot level.
The general country rock of the Monument is the same granite that occurs in the Dillon and Strong mines. The same "basalt" dike noted in the Dillon passes through the Monument workings west of the shaft, running nearly parallel with the Monument lode.
No phonolite dikes were noted in the workings, but the dike which occurs in the Dillon east of the shaft may, perhaps, be cut in the eastern part of the 309-foot Monument level. No attempt was made to determine this point at the time of visit.
The ore of the Monument occurs as short pay shoots in bodies which are structurally narrow mineralized sheeted zones in the granite. The sheeted zone of the Monument vein is from 3 to 4 feet wide, but has produced very little ore. The Kurtz lode, however, which is similar in structure, contains good ore above the 285-foot level and has been stoped for a length of 125 feet on the 207-foot level.
It is noteworthy that very little ore has been found at the junction of the Kurtz and Monument lodes, the ore on the Kurtz usually beginning a few feet away from the Monument. The Kurtz pay shoot is the longest known in the mine.
On the 475-foot level a narrow pay shoot has been stoped for about 100 feet on a sheeted zone which lies 70 feet west of the shaft between the Monument and Par Value lodes and strikes N. 17° W. This zone of fissuring is apparently not known on the level above.
Near the south end of this same level another pay shoot occurs in the Par Value lode, extending north and south for 20 to 25 feet from the intersection of this lode by the Stonehouse.
There was no opportunity at the time of visit for studying typical exposures of the ore. Although no good specimens Were seen, the original ore probably consists of sylvanite or calaverite deposited in the crevices of the fissure zones. It is usually more or less oxidized.