New Mexico Mineral Symposium — Abstracts

The Hansonburg mining district is on the west side of the Sierra Oscura Mountains in central New Mexico. It lies about 55 km southeast of Socorro at the northern boundaries of White Sands Missile Range. The district includes the Blanchard, Mex–Tex, Royal Flush, and Rose mines, and additional short tunnels and open-cut areas that lie 3-8 km south of NM-380 and the village of Bingham. Mining has occurred in the district since the 1880s, with the main ores of interest being fluorite, barite, and galena. Mineralization occurs as veins in steep, westerly dipping fault structures, and in highly fractured and silcified, sub-horizontal Pennsylvanian limestones immediately adjacent to the faults. Veins and adjacent mineralized rock often contain substantial open spaces and crystal-lined vugs that are exposed both in open cuts and trenches on the surface and in mine tunnels.

The Hansonburg district, and the Blanchard, Mex–Tex, and Royal Flush mines in particular, has become widely known as a source of fine crystal specimens for the past 40 years or so. However, commercial mining operations that were conducted prior to control of the claims by the current claimants were geared almost exclusively to production of ore, and surprisingly few specimens were salvaged from pre-1960s mining operations. We can only speculate about the quantity and quality of fine mineral specimens that were sacrificed to the crusher during the course of commercial mining in the district. However, we must conclude that the loss of irreplaceable material must have been substantial given the quality and quantity of specimens that are currently being produced from existing tunnels and excavations at these properties. All mineralized areas accessible to claiming are currently under the control of claimants whose sole interest is the production of mineral specimens. Some of the properties are accessible to the general public for collecting on a fee, or by-appointment basis.

We decided several years ago to increase the scale of specimen production at various locations in the district. Before this time, we had used only hand tools and occasional digging and blasting to produce material. We decided to try a somewhat-larger mechanized operation using a tracked Caterpillar 320L excavator in conjunction with hand-digging to recover specimens. This increase in scale has proved successful (some years we even made expenses!), and the machine has been used for the last 4 yrs to excavate mineralized areas exposed in existing open cuts on the surface. The operation has taken place around Memorial Day of each year and has lasted about 10 days each time. Limited specimen extraction with hand tools also has taken place in some of the underground workings at these properties.

Minerals have been produced from the Blanchard, Mex–Tex, and Rose mines. At the Mex–Tex mine, we have found high-quality, rare secondary minerals and more common species. The secondary minerals include brochantite, crandallite, creedite, cyanotrichite, libethenite, linarite, murdochite on smoky quartz, plumbogummite, pseudomalachite, spangolite, and tsumebite. The spangolite (up to 3 mm crystals) and cyanotrichite specimens are among the best ever found in New Mexico. Fine clusters and groups of both amethystine and smoky quartz (some liberally sprinkled with murdochite microcrystals) have also been produced from the Mex–Tex mine. From the Rose mine have come fine sky-blue fluorite crystal groups with barite blades. Also, a large pocket at the Royal Flush mine produced in excess of 4,000 lbs of specimens with small but gemmy fluorite cystals on matrix.

The operations at the Blanchard mine have also been productive and successful. Sky-blue, purple, and pale-green fluorite crystals up to 7 cm on edge, in mainly the cubic to modified cubic habit, but also in the hexoctahedral and dodecahedral habits, have been produced throughout the Blanchard mine area. Fluorite and barite specimens sprinkled with small (up to 2 mm) butterscotch-yellow wulfenite crystals were found near a large wooden ore bin on the property. A large crystallized cavity was discovered in one of the "Sunshine" tunnels in 1996, and much of the ceiling proved to be coated with dark-blue fluorite and highly altered galena crystals to 5 cm on an edge and barite. Fortunately, almost all the crystallized material was attached to a 15-cm-thick layer of silicified limestone that had either already gently slumped to the floor of the cavity or was partially detached and therefore easily removed. As a result, almost all crystal specimens were recovered with very little to no damage—a very unusual and fortuitous set of circumstances! The New Mexico Museum of Natural History and Science purchased most of the larger specimens from this cavity and plan to use this beautiful material for a crystal cavity reconstruction at the museum. We are gratified that this New Mexico treasure will remain in New Mexico. Water-clear, color-zoned fluorite cubes to 4 mm, with hexoctahedral modifications, were also found in this pocket.

Other minerals produced from the various Blanchard mine tunnels and surface workings include linarite and brochantite in association with fluorite, and beige-colored bubbly smithsonite. A very fine cabinet-sized specimen consisting of blue fluorite cubes to 5 cm nested within large lustrous cream barite crystals to 16 cm was, after much careful and skillful effort, recovered with very little damage from another Sunshine tunnel. This exceptional specimen passed through several mineral-dealer's hands. It was ultimately purchased by and is on display at the New Mexico Bureau of Mines and Mineral Resources Mineral Museum in Socorro.

Finally, one of us (Sanders) has been working on geologic mapping of the main tunnels at the Blanchard mine to determine how the mineralized zones exposed in each of the tunnels are connected to each other, both horizontally and vertically. The Sunshine Mining Company of Boise, Idaho conducted a large-scale exploration project at the Blanchard mine from 1958 to 1960 and excavated most tunnels at the property. As part of this study, Sunshine was contacted to determine if they still had maps, reports, and other information that was undoubtedly generated during this project, and if such information could be released to the current claimant if it still existed. Sunshine officials contacted about this project had no recollection of it, but they graciously allowed us to search through archived data stored in northern Idaho. Plan and cross-section maps produced during their project were found. The mining company again generously allowed copying of any information that was of interest. This historical Sunshine data will be used in conjunction with the ongoing geological study to help determine the amount of potentially productive mineralized ground that remains at the Blanchard mine. If reserves prove sufficient, if it appears that a sufficient quantity and quality of mineral specimens can be produced from those reserves to support an economically viable mining operation, and if the cost of other safety and logistical issues can be overcome, then underground specimen mining may at some point take place at the Blanchard mine.