New Mexico Mineral Symposium — Abstracts

New Mexico has been known for a number of years as one of the world’s premier locations for spangolite. This rare and beautiful, hydrated, copper aluminum sulfate, is known primarily as microcrystals. Highly acclaimed are noteworthy specimens from the Blanchard and Mex-Tex mines in the Hansonburg mining district near Bingham in Socorro County.

A single specimen recovered in 1930 from the Magdalena district and subsequently identified as spangolite by W.T. Schaller in 1937 (Northrop 1959) cannot be located and its identity remains questionable, as no further accounts have been recorded from the district. It was positively identified in New Mexico in 1953 by Arthur Montgomery in specimens provided by W.H. Wright of Santa Fe (Northrop 1959).

A paper by L.W. Talbot in the 1974 New Mexico Geological Society’s 25^th field conference guidebook reported an occurrence of spangolite at the Nacimiento copper mine near Cuba, New Mexico. A paper describing this occurrence (Hauff and Talbot 1974) was to be published but apparently never made it to press. No further reports of spangolite from this location were noted until a discovery by Rex Nelson in March 2012 (Nelson, pers. comm. 2013). Small crystals were found in a fossil log, partially replaced by chalcocite in the Triassic Agua Zarca sandstone in the Nacimiento pit. The crystals are up to .2 mm with a dominant pedion and minor pyramidal and prism faces. They were found in association with cyanotrichite.

Spangolite was reported from the Buckhorn mine in the Red Cloud district near Corona, in Lincoln County in November 1993 (DeMark and Hlava 1993). Crystals up to 2.2 mm, dominated by prism and pyramidal faces were found associated with cyanotrichite and brochantite. The crystals were found in situ at the bottom of a 45’ deep shaft. A comprehensive report on the Buckhorn mine (Schreiner 1993) describes the mineralogy and layout of the shafts and adits constituting the Buckhorn mine. The site has since been reclaimed, and the shaft is no longer accessible.

A site near the portal on the south side of the Sunshine # 6 adit at the Blanchard mine was, for many years, the only are known area for spangolite at the Blanchard mine. This adit was buried and closed in 1979, and the spangolite area is now totally inaccessible. In May 2003 while investigating a boulder for brochantite in the debris field below the Sunshine #6 adit, a piece of rock popped out with a single spangolite crystal over 6 mm long! This is the largest known crystal from the Blanchard mine. Several other large crystals were also found. Spangolite has also been found in the Sunshine #4 adit. These crystals are quite small (less than .2 mm) and associated with cyanotrichite. The Sunshine #1 adit has produced very few spangolite specimens. The crystals are less than .3 mm and typically composed of pyramidal and prism faces. More recently, a short, open adit between the Sunshine #3 and Sunshine #4 adit (dubbed the Sunshine #3 ½ by Rex Nelson) was found by Rex in November 2008 (Nelson, pers. comm., 2013) to have spangolite in association with cyanotrichite, brochantite, and linarite. Very attractive specimens have been recently collected from this area featuring these three species.

In June 1995, an exceptional find of spangolite was uncovered during a mechanized dig at the Mex-Tex mine. An area at the base of the wall on the south side of the main portal was opened that contained very rich specimens of dark, lustrous spangolite crystals and aggregates up to 3 mm across. Some of these specimens have overgrowths of creedite (rare in the district) and are intergrown with lustrous, bright green brochantite. A few specimens exhibiting an unusual vermicular habit were also unearthed. Overall, these specimens are undoubtedly among the finest New Mexico spangolites, and they now grace private and public collections around the world.

This is the current story of spangolite in New Mexico. The next chapter, however, remains unwritten. Perhaps some sharp-eyed, diligent collector will add an additional page to the story.

References:

1. De Mark, R. S., Hlava, P. F., 1993, Spangolite and other secondary minerals from the Buckhorn mine, New Mexico Geology, pp 15, 19.
2. Hauff, P. L., Talbot, L. W., Morse, A., 1974, Spangolite—an occurrence at Cuba, New Mexico: Mining Society of America, winter meeting, Tucson, Arizona, paper in progress.
3. Northrop, S. A., 1959, Minerals of New Mexico, revised: University of New Mexico Press, Albuquerque, 665 pp.
4. Schreiner, R. A., 1993, Mineral investigations of the rare-earth-element-bearing deposits, Red Cloud mining district, Gallinas Mountains, Lincoln County, New Mexico: U.S. Bureau of Mines, Open –file report 99–93, 189 pp.
5. Talbot, L. W., 1974, Nacimiento pit, a Triassic strata-bound copper deposit: New Mexico Geological Society Guidebook 25^th field conference, pp. 301–303.