Standard rocks samples

The ashes were analyzed by emission spectroscopy using a d.c. arc and a Jarrell-Ash Wadsworth spectrograph. A visual comparison of line intensities with standard rock samples established the approximate elemental concentrations. Based on experience, the true content of any element is most probably within the range 2 to 0.5X the stated value. 

Figure 28-4 The mass spectrum of a standard rock sample obtained by laser ablation/ICP-MS. Major components (%) Na, 5.2 Mg, 0.21 Al, 6.1 Si, 26.3 K, 5.3 Cu, 1.4 Ti, 0.18 and Fe. 4.6. (From Inorganic Mass Spectrometiy, F. Adams, R. Gijbek, and R. Van Grieken. Eds., p. 297. New York Wiley. 1988. This material is used by permission of Wiley-Liss, Inc., a subsidiary of John Wiley Sons, Inc.)...

U. S. Geological Survey Standard Rock Samples (7) Diabase 1 1 0.110... 

U. S. Geological Survey standard rock samples. Volcanic ash flows and lava of New Zealand are rich in selenium. One may conclude that the selenium content of igneous rocks ranges from 0.004 to 1.5 ppm, that some andesitic ash flows contain unusually high amounts of selenium, and that lavas are usually higher in selenium than intrusives. 

With proper correction for matrix effects. X-ray fluorescence spectrometry is one of the most powerful tools available for the rapid quantitative determination of all but the lightest elements in complex samples. For example. Rose, Bornhorst. and Sivonon have demonstrated that twenty-two elements can bo determined in powdered rock samples with a commercial EDXRF spectrometer in about 2 hours (1 hour instrument time), including grinding and pellet preparation. Relative standard deviations for the method are better than 1% for major elements and better than y/o for trace elements. Accuracy and detection limits as determined by comparison to results from international standard rock samples were comparable or better than other published procedures. For an e.xcellent overview of XRF analysis of geological materials, see the paper by Anzelmo and Lindsay. ... 

In Table 35, practical detection limits by laser sampling ICP-MS for two international standard rock samples are given. 

Table 35 Practical detection limits (PDL) for some elements obtained by laser sampling ICP-MS for two international standard rock samples. (Source P. Arrowsmith, Anal. Chem., 1987, 59, 1437)...

REE content [in ppm (wt)] in USGS standard rock sample BCR-1 (Columbia River Basalt). 

A is the cross-sectional area of the rock sample in cm L is the length of the rock sample in cm APcore is the pressure drop across the rock sample in standard atmospheres... 

A 13C/12C ratio about 3% above that of a standard value (the so-called VPDB standard) had been found in western Australian rock samples from the Pilbara Formation similar values were found for the Isua rock. However, since this no longer had its original morphology, the yeast-like relicts found by Pflug (1978) may not be real, and doubts have been cast, in particular by the American scientists J. W. Schopf andE. Roedder (Breuer, 1981,1982). Neither the Isua microfossils nor their 13C/12C isotope ratio could convince Bill Schopf that 3.8-billion-year-old samples were really involved. The Isua graphite flakes could also be a charred residuum from the... 

Nuclear bombardment reactions in which the product is radioactive constitute the basis of radioactivation analysis (p. 456). Although in principle any bombardment-decay sequence may be used the analyst is largely concerned with thermal neutron activation. Equation (10.13) relates the induced activity to the amount of the parent nucleide (analyte). However, practical difficulties arise because of flux inhomogeneities. It is common therefore to irradiate a standard with very similar characteristics alongside the sample, e.g. for a silicate rock sample a standard solution would be evaporated on to a similar amount of pure silica. On the assumption that identical specific activities for the analyte are then induced in the sample and standard, the amount w2 of analyte is readily calculated from... 

Laser ablation ICP-MS (LA-ICP-MS) was established in the early 1990s as a potential routine tool for the measurement of trace and ultra-trace elements in silicate systems for geology. Early studies (Perkins et al. 1993) used sample preparation techniques identical to that used to prepare rock samples for WDXRF, i.e., either a pressed powder disk or a glass bead fusion method (see Appendix VIII). Such studies concluded that LA-ICP-MS had the potential to surpass XRF in terms of the limits of detection achieved and INAA in terms of the speed of analysis (Perkins et al. 1993 481). It has long been recognized that the main limit on the quantitative performance of LA-ICP-MS is the homogeneity at the trace and ultra-trace level of the solid calibration standards available. Subsequent work (e.g., Hollecher and Ruiz 1995, Norman et al. 1996) has demonstrated that some of the international... 

Xie, X.J. Yan, M.C., Li, L, Shen, H. 1985. Usable values for Chinese standard reference samples of stream sediments, soils and rocks GSD9-12, GSS1-8 and GSR1-6. Geostandards Newsletter, 5, 211-280. 

Accuracy, Precision, and Detection Limits — Analytical cost, accuracy, precision, and detection limits are the four main evaluation criteria for selecting an analytical method. Detection limit information will not be givdn here, as it is easily obtained from the literature or from instrument manufacturers. The analysis of NBS orchard leaves and bovine liver is often used to demonstrate the accuracy and precision of ICP analysis. We feel that the analysis of United States Geological Survey (USGS) and Canadian Centre for Mineral Energy Technology (CANMET) standard rocks, is a more rigorous test of ICP analytical accuracy because of the resistance to sample... 

Mean heat production. Standard deviation on the heat produetion distribution. Number of sites. Analyses were made on mixed powders, implying that the standard deviation of the analyses underestimates the true spread of values for individual rock samples. Average calculated by weighting according to the abundances of the different rock types. Baltic Shield data compiled from Hanski (1992), Eilu (1994),... 

There are a variety of compilations of the concentrations of many of the chemical elements for both crustal rocks (see above and Volume 3) and for soils (Bowen, 1979 Shacklette and Boerngen, 1984). In the case of soils, the samples analyzed are usually from a standard surface sampling depth, or from the uppermost horizon. Thus, these samples give a somewhat skewed view of the overall process of soil formation because, as will be discussed, soil formation is a depth-dependent process. Nonetheless, the data do provide a general overview of soil biogeochemistry that is applicable across broad geographical gradients. 

Cabell and Smales (IS) have described the application of neutron activation to the determination of rubidium and caesium in international standard rocks, lepidolites, samples from the Skaergaard Intrusion of East Greenland, and some stony meteorites. Smales and Salmon 9S) had previously determined the same two elements in sea water after a preliminary concentration on an ion exchange resin, and directly in other materials of geochemical interest. 

Table I gives the values used for the USGS standard rocks both at Brook-haven National Laboratory and in the Conservation Analytical Laboratory of the Smithsonian Institution. The values reported for the Smithsonian were obtained by preparing the USGS standard rocks by using the method described earlier and analyzing them using NBS Glass Standards 610 and 612 and Spex Industries Atomic Absorption Standards. Twenty-four samples of majolica that had been analyzed by INAA were analyzed for comparison using DCP-OES. The data for three of these samples are given in Table II. Additional comparative data exist for SA 67, 76, 77, 84, and 94 and SC 03-21 for the 15 oxides that appear in Table II and in Reference I.

Our trace element data base now contains analyses of 586 samples of native copper from deposits throughout the world. However, the sample sources are skewed toward the northern United States, especially the Lake Superior region. Trace elements can be considered as those normally found in concentrations below 100 ppm (i.e., below the 0.01% normally used as the lower limit of standard rock and mineral analyses). Trace elements do not play a major part in the physicochemical reactions that take place in the formation of geologic deposits. They are either concentrated in or dispersed throughout rock, mineral, and ore deposits... 

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