New Mexico Mineral Symposium — Abstracts

The 1990 New Mexico Mineral Symposium reported minerals of the Mex-Tex group, Bingham, New Mexico (Massis, 1990). This is a report on recent developments at the Mex-Tex. During early February 1991, a major collapse at the main or upper workings covered and buried the most productive mineral-collecting area of the Mex-Tex group. The collapse occurred when nobody was present. It is felt that the increased aircraft activity over the area released a sonic boom nearby that started the collapse. This event, the collapse, was not expected.

A 60-70-ft section subsided, collapsed, and covered nearly all the familiar under¬ground collecting sites. The only underground section remaining is the extreme backside, located in the southeast section of the mine. This section is still unstable with evidence of recent falls from the ceiling that continue to drop in various-sized sections. The outside surface above these workings is still observed to be settling, eight months after the initial collapse.

The collapse has significantly reduced the quantity of fine mineral specimens being collected. The 15-20-ft overburden now covering this area is essentially void of mineraliza¬tion. Only one mineralized, specimen-producing zone has been found at the surface. This mineralized zone produced a small suite of fine fluorite, barite, and galena specimens. The forms and colors are new for the Mex-Tex group. At least four new fluorite crystal forms were found, highly modified cubic or octahedral forms. The colors are dark purple to gray blue with individual crystals exceeding three inches. A number of the fluorite specimens collected are museum quality. Barite specimens though small, less than two inches on a side, were free formed with no terminations, clear to light yellow, and many times quite "gemmy." Some modified cubic galena specimens, new forms for the Mex-Tex group, were also collected.

Though specimen production and collecting has diminished tremendously, small pockets throughout the Mex-Tex group continue to be found. Hard work moving significant quantities of overburden is now required to open pockets. This year, 1991 (including the latter part of 1990), the Mex-Tex group has produced significant finds that include fine light-green hex-octahedral and modified cubic fluorites, typical light-blue to clear hex-octahedral fluorites, showy murdochite on quartz, numerous combinations of spangolite, brochantite, and linarite with other unidentified colored minerals, a suite of creedite, small linarite crystals in association with fluorite and galena, and wulfenite crystals. Large plates of small quartz crystals, both smoky-tipped and amethystine, continue to be found.

There are no plans to remove the 15 to 20 ft of overburden covering the main specimen-producing area. Small significant finds will continue to occur elsewhere but it appears specimen production will diminish from this area. Collecting at the Mex-Tex, especially the upper workings, is extremely dangerous and is discouraged for the foreseeable future.
 

References:

1. Massis, T., 1990, Minerals of the Mex-Tex group, Bingham, New Mexico: New Mexico Institute of Mining and Technology, 11th New Mexico Mineral Symposium, Proceedings, p. 12-13; New Mexico Geology, 1991, v. 13, no. 2, p. 40.