New Mexico Mineral Symposium — Abstracts

The Hansonburg mining district, especially the mines of the Blanchard group located near Bingham, New Mexico in Socorro County, is well known to mineral collectors. Located nearby, within this district, is another series of mines not generally known to collectors called the Mex-Tex group that in the last three years has produced a large suite of superb mineral speci¬mens that rivals those of the Blanchard group.

The Mex-Tex group of mines consists of numerous claims that were mined for barite until about 1960. More than 96% of the barite produced in New Mexico has come from the Mex-Tex group. Mining activities for ore have occurred sporadically since then with very little production. In 1987, after abandonment of the claims by Western General Mining, the Mex-Tex group was claimed by mineral collectors for specimen purposes.

The Mex-Tex group consists of two distinct areas. The first or main area running north/south for approximately one-half mile is located along the western escarpment of the northern reaches of the Sierra Oscura mountain range and has been known tradition¬ally as the Mex-Tex mine. It is located about one mile north and slightly east of the Blanchard group. The second area, just north of the main Mex-Tex mine and across an arroyo, is better known as the Royal Flush mine.

Extensive mineralization is found primarily between a shale zone and a limestone formation, particularly along fault lines. The ore shoots are banded, crustiform, and quite vuggy. Large pockets with coarse crystals are found throughout. The main Mex¬Tex group consists of many pits, adits, shafts, tunnels, and stopes along this one-half-mile stretch. Because of their shallow nature, extensive weathering has taken place and cave-ins have occurred. ALL UNDERGROUND WORKINGS ARE CONSIDERED QUITE DANGEROUS AND HAZARDOUS.

The bulk of the mineral specimens found consist of combina-tions of four minerals: fluorite, galena, barite, and quartz. Any of the following can also be present on the four main miner¬als: linarite, plattnerite, murdochite, brochantite, spangolite, cerussite, anglesite, wulfenite, caledonite, chalcopyrite, hemimorphite, calcite, and selenite. Numerous striking/aesthetic plates, groups, and clusters have been found up to 30 inches in diameter.

Fluorite from the Mex-Tex group has proved the most desir¬able of the minerals found. At the main Mex-Tex mine, it is seldom found as simple cubes. Complex forms prevail, with the most abundant being the hexoctahedral form. Even the cubic forms when found are highly modified, with edges rounded or other crystal faces showing. Colors include the classic "Bingham blue," surface blue (typical of Naica, Mexico fluorite), green (various shades), clear, and purple/maroon. Single fluorite crystals in combination with other minerals sometimes exceed 3 inches across.

Quartz crystals though small, seldom exceeding one inch in length, are quite beautiful and almost always present with other minerals as showy groups. In addition to clear quartz, both amethystine and smoky are also found. The smoky color is quite attractive, for it is almost always present on the crystal tips only and not within the body. When the smoky color is present, fluorite association is most often the classic "Naica blue" or a light-green color, a most unusual but striking combination.

Galena is always found covered with other minerals. Crystals as large as 4 inches have been collected. Many times pseudomorphs of galena completely replaced by cerussite are found. Barite blades to 12 inches have also been collected. Most recently, one or more new forms of wulfenite for the Bingham area have been found at the Mex-Tex group. Though individual crystals of the other minerals present at the Mex-Tex are small, they can cover large areas on a group. Examples are murdochite on quartz and plattnerite on quartz, fluorite, and galena.

Most if not all of the easy finds and pockets have been located. Future success will involve considerable work but may be productive. The danger in the remaining workings will limit the amount of future success for mineral specimens at the Mex-Tex mine and workings.