New Mexico Mineral Symposium — Abstracts

The mention of the Tombstone district of southeastern Arizona conjures up romantic images of the old West including prospectors braving hostile Apaches to make the initial discovery, the Earp brothers and the "Shoot out at the OK Corral," and enough wealth pouring out of the mines to support a non-stop 24/7 poker game...with a $1,000 buy-in for 5 yrs! Of course the prospector sold out cheap and died penniless, the Earp brothers' reputation has tarnished with time, and the fabu¬lous ores played out long ago. Today, the Tombstone district is a world-renowned tourist trap, and the mines are largely inaccessible. However, the Tombstone district has produced a number of rare tellurium oxysalts, is type locality for nine such species, and a number of unknowns are awaiting description.

Tombstone mining commenced about 1881 on high-grade ores that cropped out on the surface. These bonanza oxide ores were rapidly followed to the water table, about 150 m below the surface. Massive pumps were installed to allow following the rich underlying sulfide ores to depths ulti¬mately reaching over 350 m. The pumps were unable to hold back the water influx, and when one pump failed in the 1890s, the entire district flooded rapidly to the water table. One later attempt was made in 1912 to dewater the mines and pursue deep ores, but except for this, all twentieth century mining was focused on scavenging remnants and lower-grade ores bypassed in the rush to follow bonanzas to depth. Total district production is estimated to be 2,700,000 tons, grading: 1.53 grams per ton Au; 372 grams per ton Ag; 0.8% Pb; 0.02% Zn; and 0.13% Cu (Titley, 1993). These are average grade figures and do not begin to reflect the extremely high gold and silver grades found in the enriched upper parts of the system.

Tombstone mineralization is hosted in a thick sequence of Paleozoic carbonate rocks uncon-formably overlain by Cretaceous shales, sandstones, and limestones. Structurally, the Tombstone district is folded into a series of northwest-trending folds cut by northeast-trending faults. A large granitic porphyry stock with related rhyolitic volcanic rocks abuts the Tombstone district to the west. Bimodal, rhyolite-lamprophyre dikes are emplaced along several of the northeast-trending faults. Mineralization consists of gold-silver-tellurium veins developed along the northeast-trend¬ing faults and associated lead-zinc-copper-silver replacement mantos or saddle reefs (rolls) that lie along the crests of the tight northwest-trending folds—immediately below shale beds. The cross¬cutting relationships between these two are unclear, but the veins are probably younger. Alteration includes pervasive argillic alteration of the igneous rocks and marbelization, skarn, and silicifica¬tion of the sedimentary rocks. The Tombstone district is zoned from a copper-zinc-gold center to lead-zinc-silver to peripheral manganese-silver over about 6 km. The primary vein mineralogy includes: empressite, hessite, krennerite, tellurium, rickardite, and altaite (probably) with quartz, calcite, fluorite, and adularia gangue. Replacement bodies were dominantly composed of galena, sphalerite, pyrite, chalcopyrite, tetrahedrite, and alabandite with similar gangue. The distal man¬ganese mineralization is dominated by soft manganese oxides. Oxidation is nearly complete to the water table except for some silica-armored zones.

Tellurium species
The distinctive green colors of the secondary tellurium species are almost infallibly associated with native gold and silver halides, and their utility as a guide to riches was clearly recognized early in the Tombstone district. Stopes in the highest-grade zones have literally been scraped to the lime¬stone walls by armies of miners working with single jacks and hand chisels. Emmonsite, recog-nized as unusual, described as a new species in 1885, is the oldest type species from the Tombstone district, and probably came from a high-graded underground ore sample. The remainders of the species are micro-minerals described in the late 1970s and early 1980s by Sid Williams, working from dump samples. Most of the dumps were lost to early 1980s open-pit, heap-leaching opera¬tions, and the thoroughness of underground mining makes it very difficult to find more than scraps of overlooked tellurium-bearing materials. Nonetheless, a late 1980s exploration program that included systematic underground mapping resulted in the location of a few small areas of rich tellurium-oxysalt mineralization and the discovery of many district type species in situ. This has also resulted in the recognition of several attractive, although as yet, undescribed species.

It is worth emphasizing that the underground workings are in very poor condition and extremely hazardous. Most underground access is sealed, and residents living near the mine entrances do not hesitate to call the police when they see unauthorized activity.

Secondary tellurium species*
Tombstone district, Cochise County

(*type locality species in bold)

Compiled from:
Anthony et al., 1990, Handbook of Mineralogy
Anthony et al., 1995, Mineralogy of Arizona
Gaines et al., 1997, Dana's New Mineralogy
Mandarino, 1999, Fleischer's Glossary of Mineral Species

Cesbronite—Cu₂⁺⁵(Te⁴⁺O₃)₂ (OH)₆*2H₂O, orthorhombic, reported by Anthony et al., 1995.
Choloalite—Cu₂Pb(Te⁴⁺O₃)₂, cubic, dump between Grand Central and Little Joe shafts.
Dugganite—Pb₃Zn₃T⁶⁺As₂O₁₄, hexagonal, Emerald mine dumps (Little Joe, Old Guard), 1978,
named for Marjorie Duggan who performed the analyses.
Emmonsite--Fe³⁺2Te⁴⁺₃O₉*2H₂O, triclinic, unknown locality (Emerald mine dumps, Little Joe shaft dump, Grand Central dump, Empire mine, underground), 1885, named for Samuel Franklin Emmons, economic geologist with USGS. Original type material almost certainly rodalquilarite!
Fairbankite--PbTe⁴⁺O₃, triclinic, Grand Central mine dumps, 1979, named for Nathaniel Kellog
Fairbank, an important entrepreneur in early Tombstone.
Frohbergite—FeTe₂, orthorhombic, Joe shaft dump.
Girdite—Pb₃H₂(Te^₄₊O₃)(Te⁶⁺O₆), monoclinic, Grand Central mine dumps, 1979, named for Richard Gird (1836-1910), mining engineer and assayer who made the first rich silver assays from the Tombstone district.
Graemite—Cu²⁺Te⁴⁺O₃•H₂O, orthorhombic, district (Gaines et al., 1997).
Khinite—PbCu²⁺₃Te⁶⁺O₄(OH)₆, orthorhombic, Old Guard mine dumps (Empire, underground), 1978, named for Ba Saw Khin, petrographer; compare to hexagonal-trigonal for parakhinite.
Mackayite—Fe³⁺Te₂O₅(OH), tetragonal, Toughnut-Empire mine.
Mroseite—CaTe⁴⁺(CO₃)O₂, orthorhombic, Tombstone Exploration Incorporated pit (=Contention-Tranquility Zone).
Oboyerite—Pb₆H₆(Te⁴⁺O₃)₃ (Te⁶⁺O₆)₂*2H₂O, triclinic, Grand Central mine dumps, 1979, named for 0.
(Oliver) Boyer, one of the first stakers of the Grand Central claim. Parakhinite—Cu²⁺₃PbTe⁶⁺0₆(OH)₂, hexagonal-trigonal, Emerald mine dumps (Empire under-
ground), 1978, named in allusion to its dimorphous relationship to khinite.
Paratellurite—TeO₂, tetragonal, Little Joe mine dump.
Quetzalcoatlite—Zn₈Cu²⁺₄(Te⁴⁺O₃)₃(OH)₁₈, hexagonal, Empire mine.
RodaIquilarite--H₃Fe³⁺₂₍Te^₄₊O₃)₄Cl, triclinic, Grand Central mine dump.
Schieffelinite—Pb(Te⁶,S)O₄•H₂O, orthorhombic, Little Joe and Grand Central mine dumps, 1980, named for Ed Schieffelin, stagecoach driver and prospector who "found his tombstone" and is credited with discovering the Tombstone district.
Sonoraite--Fe³⁺Te⁴⁺O₃(OH)•H₂O, monoclinic, Little Joe shaft dump.
Tlapallite—H₆(Ca,Pb)₂(Cu²⁺, Zn)₃(SO)₄( Te⁴⁺O₃)₄ (Te⁶⁺O₆), monoclinic, Lucky Cuss mine dump. Winstanleyite--TiTe4+308, cubic, Grand Central mine dump, 1979, named for Betty Joe Winstanley, finder of first specimen
Xocomecatlite—Cu²⁺₃Te⁶⁺O₄(OH)₄, orthorhombic, Emerald mine dump.
Yafsoanite—Ca₃Zn₃(Te⁶⁺O₆)₂, isometric, Empire Mine underground; this is the material used to determine the garnet structure of yafsoanite.

References:

1. Titley, S. R., 1993, Characteristics of high temperature carbonate-hosted massive sulfide ores in the United States, Mexico, and Peru; in Kirkham, R. V., Sinclair, W D., Thorpe, R. I., and Duke, J. M. (eds.), Mineral deposit modeling: Geologic Association of Canada, Special Paper 40, pp. 585-614.