Virgil W. Lueth - Research Summary
Jarosite Geochemistry and Geochronology
Geochronology of Hydrothermal Mn Deposits
Solid Solution Behavior in Sulfides
Groundwater Mineralogy
Mineralogy of New Mexico
Skarn and Carbonate Replacement Deposits
Geologic Membrane Phenomena
Studies in Igneous Petrology
Ore Deposit Studies
Geochemistry of Arsenic, Antimony and Bismuth
Geochemistry and Geochronology of Jarosite
 Massive jarosite and hematite mineralization Level 1, upper stope, Copiapo Jarosite Mine, NM |
Jarosite, a potassium iron sulfate, is a member of the alunite group. The mineral contains K, SO4, and OH. Accordingly, it can be dated using K/Ar or Ar/Ar methods and isotopic values of sulfur, oxygen, and hydrogen determined. Previous workers identified three types of jarosite, based on stable istope characteristics and geologic occurrence: supergene, sedimentary, and steam-heated. My collaborative work has led to a definition of a fourth type: sour gas jarosites. By determining the isotopic characteristics of jarosite, one can use these characteristics to infer water sources, sulfur sources, and paleoclimate conditions during the formation of the mineral. We are currently applyingthese principles to the formation of barite-fluorite deposits in the Rio Grande rift of New Mexico and the weathering of ore deposits on the flanks of the rift. |
 Virgil Lueth (left) and Lisa Peters (with sledge) sampling manganese oxide ores at the Manganese Chief mine, Magdalena Mtns, NM. |
Hydrothermal managanese oxide ores are abundant in New Mexico. We are using cryptomelane to directly date hydrothermal mineralization and also determine the duration of mineralization activity. Lisa Peters and I have successfully dated a number of deposits in New Mexico. We are continuing to develop better separation and analytical techniques to date the manganese deposits around the state. |
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The solid solution behavior of sulfide minerals has been studied intensively in recent years and some systems have been modeled by thermodynamics. My research has concentrated on the solid solution behavior of sulfide minerals in natural systems, mainly bismuthinite - stibnite and galena. Miner's tales often speak of "silver-bearing" galena in the octahedral form or in distorted forms - this has not been observed in my studies. By documenting natural variation in sulfides we can constrain thermodynamic models, predict metal zoning and ore grades, and infer the fractionation of hydrothermal fluids. |
 Travertine mineralization west of Belen, NM. |
An example of groundwater mineralization occurring at the surface (a spring). Magnetite minerals occurring in domestic water supplies was brought to my attention while I was at Tarleton State University in Texas. My students and I identified favorable lithologies and water chemistry that were common to magnetite contamination. The physical and chemcial characteristics of the magnetite in relation to the geologic distribution suggests the "contamination" is caused by iron reducing bacteria that live naturally in the aquifer. |
 Barite on fluorite from the Sunshine No. 6 Mine, Hansonburg District, Socorro Co., NM. Mined in 1998. This specimen was offered to the museum twice, we took it the $econd time...what a story. (Specimen 40 cm). |
Serving as the state mineralogist, much of my time and expertise is spent on researching and documenting the mineralogy of New Mexico. As curator of the Mineralogical Museum I have the opportunity to study many unusual and historic specimens. Many of these studies are reported at the New Mexico Mineral Symposium every November. Robert W. Eveleth, the associate curator of the musuem, and I have made documenting the history of the 100 year old museum and its collections a priority. |
 Skarn mineralization in the Lake Valley Formation,Continental Open Pit, Fierro, Grant Co., NM. A diagram and discussion of this outcrop is in Marco Einaudi's paper in "Advances in the Geology of the Porphyry Copper Deposits," S. Titley ed. (1983). This photo is from my MS thesis. |
Skarn mineralization refers to calc-silicate rocks the formed by replacement of originally carbonate- rich rocks. They differ from carbonate replacement deposits in the amount of calc-silicate development. However, there is mounting evidence they are produced by similar processes. This outcrop photograph is in a zone where the transition from skarn to carbonate replacement occurs. These types of deposits have been major producers of copper and zinc in New Mexico. |
Geologic Membrane Phenomena
 A Portable geologic membrane from the Abo Fm., Torrence Co., NM. Note the copper mineralization above the shale layer. This sample is from the Bluestar Mine, Scholle district. (20 cm tall). |
Geologic membranes behave much like other natural membranes by allowing the passage of water and leaving dissolved salts behind. We have tried to apply membrane principles to red bed copper deposits. These deposits are fairly common in New Mexico, though rather small. We have studied the deposits in the Pastura and Scholle districts. Geologic membranes may be the primary concentration mechanism for copper in these deposits. |
 Laccolith in the southern San Andres Mountains (foreground) exhibiting fluid escape features; miarolitic cavities and aplite-pegmatite veins. Telluride mineralization is associated with this pluton. The floor of the intrusion is visible in the photo. |
Most of my research in the field of igneous petrology concentrates on the late stage processes of magma crystallization. The evolution of late stage fluids from magmas is responsible for hydrothermal ore deposits, pegmatites, and skarns. |
 The Rickardite Mine, Organ District, Dona Ana Co., NM, one of the telluride deposits in the southern San Andres Mountains. Mineralization once extended across the canyon - now in the bottom of the Rio Grande rift. |
Part of
my job title is as Economic Geologist at the NMBMMR. Accordingly,
I have studied a wide variety of ore deposits. Specialization in
skarns is one facet, however I have an interest in many types of
ore deposits - especially those found in New Mexico. Many of my
projects have been concentrated in the Organ and San Andres Mountains
where a batholith system has been dissected and tilted, revealing
a wide variety of ore deposits associated with the magmatic event.
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 My favorite elements! |
Semimetal-nonmetal elements are important components in sulfosalt
minerals and the basis of my dissertation. I have also been very
interested in the many mineralogical combinations exhibited by the
sulfosalts, telluride-tellurates and phosphate minerals. Since these
minerals are important in many ore deposits, I have made understanding
their chemical components one of my vocations. |
New Mexico Bureau of Geology & Mineral Resources
New Mexico Institute of Mining & Technology
801 Leroy Place
Socorro, NM 87801-4796
information: (575) 835-5420
fax: (575) 835-6333
http://geoinfo.nmt.edu
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