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Reinhard W. Leinz

Publications and source records attributed to Reinhard W. Leinz.

10 recordsLinked to original sources
USGS2010

Mineralogical and chemical characteristics of some natural jarosites

This paper presents a detailed study of the mineralogical, microscopic, thermal, and spectral characteristics of jarosite and natrojarosite minerals. Systematic mineralogic and chemical examination of a suite of 32 natural stoichiometric jarosite and natrojarosite samples from diverse supergene and hydrothermal environments indicates that there is only limited solid solution between Na and K at low temperatures, which suggests the presence of a solvus in the jarosite-natrojarosite system at temperatures below about 140 C. The samples examined in this study consist of either end members or coexisting end-member pairs of jarosite and natrojarosite. Quantitative electron-probe microanalysis data for several natural hydrothermal samples show only end-member compositions for individual grains or zones, and no detectable alkali-site deficiencies, which indicates that there is no hydronium substitution within the analytical uncertainty of the method. In addition, there is no evidence of Fe deficiencies in the natural hydrothermal samples. Hydronium-bearing jarosite was detected in only one relatively young supergene sample suggesting that terrestrial hydronium-bearing jarosites generally are unstable over geologic timescales. Unit-cell parameters of the 20 natural stoichiometric jarosites and 12 natural stoichiometric natrojarosites examined in this study have distinct and narrow ranges in the a- and c-cell dimensions. There is no overlap of these parameters at the 1r level for the two end-member compositions. Several hydrothermal samples consist of fine-scale (2–10 lm) intimate intergrowths of jarosite and natrojarosite, which could have resulted from solid-state diffusion segregation or growth zoning due to variations in the Na/K activity ratio of hydrothermal solutions.

Geochimica et Cosmochimica Acta↗
USGS2008

Cyanide speciation at four gold leach operations undergoing remediation

Analyses have been made of 81 effluents from four gold leach operations in various stages of remediation to identify the most-persistent cyanide species. Total cyanide and weak acid-dissociable (WAD) cyanide were measured using improved methods, and metals known to form stable cyanocomplexes were also measured. Typically, total cyanide greatly exceeded WAD indicating that cyanide was predominantly in strong cyanometallic complexes. Iron was generally too low to accommodate the strongly complexed cyanide as Fe(CN) 6 3- or Fe(CN) 6 4- , but cobalt was abundant enough to implicate Co(CN) 6 3- or its dissociation products (Co(CN) 6-x (H 2 O) x (3-x)- ). Supporting evidence for cobalt-cyanide complexation was found in tight correlations between cobalt and cyanide in some sample suites. Also, abundant free cyanide was produced upon UV illumination. Iron and cobalt cyanocomplexes both photodissociate; however, the iron concentration was insufficient to have carried the liberated cyanide, while the cobalt concentration was sufficient. Cobalt cyanocomplexes have not previously been recognized in cyanidation wastes. Their identification at four separate operations, which had treated ores that were not especially rich in cobalt, suggests that cobalt complexation may be a common source of cyanide persistence. There is a need for more information on the importance and behavior of cobalt cyanocomplexes in ore-processing wastes at gold mines.

California;Nevada;New Mexico↗
USGS2006

The use of synthetic jarosite as an analog for natural jarosite

The presence of jarosite in soil or mining waste is an indicator of acidic sulfate-rich conditions. Physical and chemical properties of synthetic jarosites are commonly used as analogs in laboratory studies to determine solubility and acid-generation of naturally occurring jarosites. In our work we have mineralogically and chemically characterized both natural and synthetic jarosites. Analysis of 32 natural hydrothermal and supergene K- and Na-jarosites indicates no (< 5 mole %) solid solution between K and Na end members. Instead, our detailed study of cell dimensions and composition reveals discrete mixtures of K and Na end members. Hydronium-bearing jarosite was detected in only one natural sample, and it appears that hydronium-bearing jarosites are metastable. Although the presence of hydronium in jarosite cannot be directly measured, we found that when synthetic hydronium-bearing jarosites are heated at 120°C for 78 days or 240°C for 24 hours, Fe(OH)SO4 is formed. The Fe(OH)SO4 is easily detected by X-ray diffraction and, hence, can be used as a post-mortem indicator of the presence of hydronium jarosite. Results from our synthetic jarosite studies indicate that natural metastable hydronium-bearing jarosite or iron-deficient forms of natural jarosite likely play an important role in acid generation in some mining wastes, but are not accurately represented by synthetic jarosite prepared by commonly used methods. The widespread practice of heating to at least 110°C after jarosite synthesis appears to drive off structural waters from protonated hydroxyl sites, which changes the properties of the jarosite. Therefore, synthetic jarosite should not be heated above 95 oC if it is to be used as an analog for low-temperature natural jarosite in mining wastes.

Conference Paper↗
USGS1985

Map showing abundance and distribution of copper in oxide residues of stream-sediment samples, Medford 1 degree by 2 degrees Quadrangle, Oregon-California

Stream-sediment sampling in the Medford 1 o x 2 o quadrangle was undertaken to provide to aid in assessment of the mineral resource potential of the quadrangle. This map presents data on the abundance and distribution of copper in the oxide residues (oxalic-acid leachates) of stream sediments and in the minus-0.18-mm sieve fraction of selected stream sediments collected in the quadrangle.

Oregon↗
USGS1985

Map showing abundance and distribution of silver in stream-sediment samples, Medford 1 degree by 2 degrees Quadrangle, Oregon-California

The Medford quadrangle is located in mountainous southwestern Oregon adjacent to the California border and a short distance east of the Pacific coast. Various parts of this area lie in different geologic provinces. Most of the western half of the quadrangle is underlain by pre-Tertiary rocks of the Klamath Mountains province. However, the Coast Range province is represented by the Tertiary sedimentary rocks in the northwest corner. Much of the eastern half of the quadrangle lies in the Cascade Range. In Oregon, because of differences in physiographic expression and age of rocks, this province is commonly divided into the more rugged High Cascade Range on the east and the more subdued Western Cascade Range on the west. This division is approximated on the map by the contact between the Quaternary and Tertiary volcanic rocks of the High Cascade Range and the Tertiary volcanic rocks of the Western Cascade Range. The geology shown is generalized from a more detailed compilation by Smith and others (1982).

Oregon↗
USGS1985

Map showing abundance and distribution of chromium in stream-sediment samples, Medford 1 degree by 2 degrees Quadrangle, Oregon-California

The Medford quadrangle is located in mountainous southwestern Oregon adjacent to the California border and a short distance east of the Pacific coast. Various parts of this area lie in different geologic provinces. Most of the western half of the quadrangle is underlain by pre-Tertiary rocks of the Klamath Mountains province. However, the Coast Range province is represented by the Tertiary sedimentary rocks in the northwest corner. Much of the eastern half of the quadrangle lies in the Cascade Range. In Oregon, because of differences in physiographic expression and age of rocks, this province is commonly divided into the more rugged High Cascade Range on the east and the more subdued Western Cascade Range on the west. This division is approximated on the map by the contact between the Quaternary and Tertiary volcanic rocks of the High Cascade Range and the Tertiary volcanic rocks of the Western Cascade Range. The geology shown is generalized from a more detailed compilation by Smith and others (1982).

Oregon↗
USGS1985

Map showing abundance and distribution of arsenic in oxide residues of stream-sediment samples, Medford 1 degree by 2 degrees Quadrangle, Oregon-California

Stream-sediment sampling in the Medford 1 o x 2 o quadrangle was undertaken to provide to aid in assessment of the mineral resource potential of the quadrangle. This map presents data on the abundance and distribution of copper in the oxide residues (oxalic-acid leachates) of stream sediments and in the minus-0.18-mm sieve fraction of selected stream sediments collected in the quadrangle.

Oregon↗
USGS1982

Map showing geochemical characteristics of rock samples from the Kalmiopsis Wilderness, southwestern Oregon

This report summarizes 1,307 semiquantitative chemical analyses of rocks collected to aid int he evaluation of the mineral resources of the Kalmiopsis Wilderness, Oreg. Chemical analyses and sample location maps are presented by Grimes, Leinz, and Speckman (1981). The area is located in the Kilamath Mountains geoporphic province of southwestern Oregon, and the area's location and boundaries are shown on the accompanying map. The geology of the study area is described by Page and others (1981), Gray (1980), and Ramp (1975). The rocks of the area cosist of dismembered ophiolite, island-arc, and sedimentary rock sequesnces that lie within the Western Jurassic belt of the Klamath Mountains. All units normally found within these assemblages are present; however, thrusting ans subsequent normal faulting have disrupted the geometric relations, producing a complexly faulted series of imbricate thrust slices.

Oregon↗
USGS1978

Spectrochemical determination of submicrogram amounts of tungsten in geologic materials

A rapid, sensitive, emission spectrographic method for the determination of tungsten in geologic materials has been developed. Sample fusion with potassium hydroxide followed by a hot-water leach renders the tungsten soluble. Acidification of the solution, reduction with titanium trichloride, complexing with thiocyanate, and ether extraction separate and concentrate the tungsten. An aliquot of the ether solution is pipetted into the cavity of a preformed graphite electrode containing 6 milligrams of sodium carbonate and is evaporated. The carbonate flux prevents formation of refractory tungsten carbide during arcing, resulting in nearly complete volatilization of tungsten during a short exposure period. Spectra from direct-current arc excitation of the tungsten are recorded on film and visually compared to standard spectra. A determination limit of 0.2-part-per-million tungsten is obtained from a 0.5-gram sample with a sample completion average of 30-50 samples per man-day.

Journal of Research of the U.S. Geological Survey↗