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R. G. Johnson

Publications and source records attributed to R. G. Johnson.

11 recordsLinked to original sources
USGS2018

Dwornikite, (Ni,Fe)SO 4 .H 2 O, a member of the kieserite group from Minasragra, Peru

A new nickel sulphate monohydrate is described from V-sulphide ore from Minasragra; it occurs associated with patronite (VS 2 ) with various sulphates, sulphur and bitumen. Dwornikite forms fine-grained white aggregates mixed with other oxidation products. Indexed X-ray powder data are tabulated; strongest lines 3.342(100) , 4.732(70), 3.024(70), 4.754(50), 3.293(35), 2.491(35) A; a 6.839, b 7.582, c 7.474 A, beta 117.85o; space group C2/c. XRF gave NiO 39.0, FeO 9.3, SO 3 42.4, = 90.7; D calc. 3.34 g/cm 3 ; mean refr. ind. approx 1.63. Unit-cell data for the synthetic end-member compounds NiSO 4 .H 2 O and FeSO 4 .H 2 O and new X-ray powder data for retgersite (NiSO 4 .6H 2 O) are given. The name is for E. J. Dwornik, mineralogist with the U.S. Geological Survey.-R.A.H.

Mineralogical Magazine↗
USGS2002

Analysis of eight argonne premium coal samples by X-ray fluorescence spectrometry

X-ray fluorescence spectrometric methods were used in the analysis of eight Argonne Premium Coal Samples. Trace elements (Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, La, and Ce) in coal ash were determined by energy-dispersive X-ray fluorescence spectrometry; major elements (Na, Mg, Al, Si, P, S, K, Ca, Ti, Mn, and Fe) in coal ash and trace elements (Cl and P) in whole coal were determined by wavelength-dispersive X-ray fluorescence spectrometry. The results of this study will be used in a geochemical database compiled for these materials from various analytical techniques. The experimental XRF methods and procedures used to determine these major and trace elements are described.

Energy & Fuels↗
USGS1986

The Georges Bank monitoring program 1985: Analysis of trace metals in bottom sediments during the third year of monitoring

Of the 12 elements analyzed in bulk (undifferentiated) sediments collected adjacent to drilling rigs on Georges Bank, only barium was found to increase in concentration during the period when eight exploratory wells were drilled (July 1981 until September 1982). The maximum postdrilling concentration of barium (a major element in drilling mud) reached 172 ppm in bulk sediments near the drill site in block 410. This concentration is higher than the predrilling concentration at this location by a factor of 5.9. This maximum barium concentration is within the range of predrilling concentrations (28-300 ppm) measured in various sediment types from the regional stations of this program. No drilling-related changes in the concentrations of the 11 other metals have been observed in bulk sediments at any of the locations sampled in this program. We estimate that about 25 percent of the barite discharged at block 312 was present in the sediments within 6 km of the rig, 4 weeks after drilling was completed at this location (drilling period was December 8, 1981-June 27, 1982). For almost a year following completion of this well, the inventory of barite decreased rapidly, with a half-life of 0.34 year. During the next year, the inventory decreased at a slower rate (half-life of 3.4 years). The faster rate probably reflects resuspension and sediment transport of bariterich material residing at the sediment surface. Elevated barium concentrations in post-drilling sediment-trap samples from block 312 indicate that such resuspension can occur up to at least 25 m above the sea floor. As the remaining barite particles are reworked deeper into the sediments by currents and bioturbation, removal by sediment-transport processes is slower. The barite discharged during the exploratory phase of drilling is associated with the fine fraction of sediment and is widely distributed around the bank. We found evidence for barium transport to Great South Channel, 115 km west of the drilling, and to stations 2 and 3, 35 km east of the easternmost drilling site. Small increases in barium concentrations, present in the fine fraction of sediment only, were measured also at the heads of both Lydonia and Oceanographer Canyons, located 8 and 39 km, respectively, seaward of the nearest exploratory well.

Georges Bank↗
USGS1984

Determination of carrier yields for neutron activation analysis using energy dispersive X-ray spectrometry

A new method is described for determining carrier yield in the radiochemical neutron activation analysis of rare-earth elements in silicate rocks by group separation. The method involves the determination of the rare-earth elements present in the carrier by means of energy-dispersive X-ray fluorescence analysis, eliminating the need to re-irradiate samples in a nuclear reactor after the gamma ray analysis is complete. Results from the analysis of USGS standards AGV-1 and BCR-1 compare favorably with those obtained using the conventional method. ?? 1984 Akade??miai Kiado??.

Journal of Radioanalytical and Nuclear Chemistry A↗
USGS1984

The Georges Bank monitoring program 1983: Analysis of trace metals in bottom sediments

From July 1981, when drilling began on Georges Bank, to May 1982, the concentration of barium, a major element in drilling mud, has increased by a factor of 3.5 in bulk sediments 200 m from the drill site in block 410 and by a factor of 2.3 at the drill site in block 312. The postdrilling barium concentrations are within the range of predriiling concentrations measured at other locations on Georges Bank. We estimate that no more than 21 percent of the barite (principal barium-bearing mineral) discharged during drilling remains within 6 km of the drill site in block 312. No drilling-related changes in the concentration of chromium or other metals have been observed in bulk sediments from blocks 410 or 312. The chemical signal of drilling mud in surficial sediments has been enhanced by separating and analyzing the sediment fraction finer than 60 ?m. Barium concentrations in the fine fraction have increased by factors of 36 and 22 at the drill sites in blocks 410 and 312, respectively. At the drill site in block 410, aluminum, chromium, copper, and mercury concentrations in this fraction temporarily increased by approximately a factor of 2 and then decreased to background. The concentrations of aluminum, barium, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, organic carbon, vanadium, and zinc in surface sediments of Georges Bank both before and after drilling are low compared to concentrations in average crustal rocks and are characteristic of unpolluted, coarse-grained sediments as found in other Continental Shelf areas.

Georges Bank↗
USGS1984

The Georges Bank monitoring program, 1984: Analysis of trace metals in bottom sediments during the second year of monitoring

Of the 12 elements analyzed in bulk (undifferentiated) sediments collected adjacent to drilling rigs on Georges Bank, only barium was found to increase in concentration during the drilling period (July 1981 until September 1982). The maximum postdrilling concentration of barium (a major element in drilling mud) reached 172 ppm in bulk sediments near the drill site in block 410. This concentration is a factor of 5.9 times higher than the predrilling concentration at that location. This maximum postdrilling barium concentration is within the range of predrilling concentrations {28-300 ppm} measured in various sediment types from the regional stations of this program. No drilling-related changes in the concentrations of chromium or other metals have been observed in bulk sediments at any of the locations sampled in this program to date. We estimate that between 21 percent and 31 percent of the barite (principal barium-bearing mineral} discharged at block 312 was present in the sediments within 6 km of the rig, 4 weeks after drilling was completed. The barite deposited near this well was found to decrease in concentration with a half-life of 0.4year. At this rate, the average barium concentration in sediments within 6 km of the drilling rig in block 312 is expected to be only 10 percent higher than the predrilling concentration within approximately 1.5 years. Although the inventory of the barite discharged on Georges Bank is based on only a few data points, most (approximately 69 percent) of the barite discharged by the eight exploratory wells apparently can be found in sediments west of the drilling locations. The increase in barium concentration above background can be measured in the fine fraction of sediment at a distance of 65 km to the west of block 312. Analysis of sediment-trap samples collected 25 m above the bottom in block 312 indicates that the dispersion of barmm-rich fine sediment is enhanced by resuspension from the sea floor and transport to the west with the mean current flow. Evidence exists of small accumulations of barium near the heads of Lydonia and Oceanographer Canyons. However, the increased concentrations can be defined only by analyzing the fine fraction of sediment.

Georges Bank↗
USGS1982

The 57 Fe Mössbauer parameters of pyrite and marcasite with different provenances

Eighteen pyrite and twelve marcasite samples which have different provenances have been investigated to determine the systematics of the influence of mineralogical and geological factors on the 57 Fe Mössbauer spectra at 298 K. The following results have been obtained: there is no ambiguity in distinguishing single phase pyrite from single phase marcasite by means of 57 Fe Mössbauer spectroscopy at 298 K. At 298 K the average electric quadrupole splitting, 〈 ΔE Q 〉, and average isomer shift, 〈δ〉, with respect to Fe metal, are 0.6110 ± 0.0030 mm s −1 and 0.313 ± 0.008 mm s −1 , respectively, for the 18 pyrites; 〈 ΔE Q 〉 = 0.5030 ± 0.0070 mm s −1 and 〈 δ 〉 = 0.2770 ± 0.0020 mm s −1 for the 12 marcasites. At 77 K, ΔE Q is 0.624 mm s −1 for pyrite and 0.508 mm s −1 for marcasite. In distinguishing pyrites from marcasites, spectra obtained at 77 K are not warranted. The Mössbauer parameters of pyrite and marcasite exhibit appreciable variations, which bear no simple relationship to the geological environment in which they occur but appear to be selectively influenced by impurities, especially arsenic, in the pyrite lattice. Quantitative and qualitative determinations of pyrite/marcasite mechanical mixtures are straightforward at 298 K and 77 K but do require least-squares computer fittings and are limited to accuracies ranging from ±5 to ±15 per cent by uncertainties in the parameter values of the pure phases. The methodology and results of this investigation are directly applicable to coals for which the presence and relative amounts of pyrite and marcasite could be of considerable genetic significance.

Geochimica et Cosmochimica Acta↗