Page 189 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

186 GEOLOGY AND ORE DEPOSITS OF SIERRA CO., N. M.
taken place. The best ore is in the andesite. The veins vary in width from 4 to 6 feet, of which 2 to 4 feet is low-grade replace- ment ore in latite porphyry dikes, and about 2 feet is high-grade ore in the brecciated andesite of the wall.
The ore minerals of the district are galena, cerusite, angle- site, sphalerite, calamine, vanadinite, wulfenite and pyrite. The gangue is principally quartz, of which some is cherty in appear- ance and some has a slightly greenish color. Silicification and sericitization of the andesite and latite is the principal form of alteration in the veins. The andesite farther away is propylit- ized, with the development of abundant chlorite, pyrite, sericite and epidote, and some secondary quartz and calcite.
At the Anniversary vein the hypogene ore mined in the brecciated portion of the vein is reported to contain approxi- mately 15 per cent lead. The low-grade latite-dike portion averages between 3 and 4 per cent lead. The silver content averages 0.6 ounces a ton for each per cent of lead in the ore. Zinc occasionally appears in the analyses of smelter shipments, ranging between 0.4 and 7.2 per cent ; however, only 299 tons shipped to the smelter, out of a total of 1,508 tons for which the writer saw the smelter returns, showed any zinc content, prob- ably because the other shipments were not assayed for zinc. Gold varied from 60c per ton in the low-grade shipments to $1.06 per ton in the higher grade material. In the upper part of the vein vanadinite is rarely observed, but in hand-sorted shipments
and concentrates, 1 per cent of V
cent of lead. On the lower levels vanadium decreased greatly.
HISTORY AND PRODUCTION
The Macho district was discovered in 1879 or 1880 by pros- pectors who had come to the region following the discovery of the rich Lake Valley ores a few miles to the north. Pay ore was found at the surface in the Old Dude, or Anniversary vein as it is now called, and some mining was done in 1880. Prior to 1904 considerable ore was produced from this vein, of which no record is now available, but which must have amounted to nearly 1,000 tons, judging from a sketch section made by the writer from verbal descriptions of the workings in the district. (See figure 15.) The mines were idle from 1904 to 1926 except for annual assessment work, a minor amount of prospecting, and possibly some small shipments. In 1926 intensive development work was begun at the vein on the Anniversary claim and was extended into the Bulldog claim lying to the northeast of it. During this period a total of about 1,640 tons of ore was shipped.
Various grades of material shipped have shown a surpris- ingly uniform relationship between the metals, as is indicated by the table below. The dump ore is a combination of a hand- sorted product and of screenings that have been jigged in a hand-operated Joplin type of jig. In general, the run-of-mine
2
0
5
is reported for each 5 per