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Inductively coupled argon plasma/optlcal emission spectrometery (ICAP/OES) Is useful as a simultaneous, multielement analytical technique for the determination of trace elements In geological materials. A method for the determination of trace-level rare earth elements (REE) In geological materials using an ICAP 63-channel emission spectrometer is described. Separation and preconcentration of the REE and yttrium from a sample digest are achieved by a nitric acid gradient cation exchange and hydrochloric acid anion exchange. Precision of 1-4% relative standard deviation and comparable accuracy are demonstrated by the triplicate analysis of three splits of BCR-1 and BHVO-1. Analyses of other geological materials Including coals, soils, and rocks show comparable precision and accuracy.

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Volcanic ash samples from the May 18, 1980, Mount St. Helens eruption were analyzed for major, minor, and trace composition by a variety of analytical techniques. Results indicate that the basic composition of the ash consists of approximately 65% SiO2, 18% Al2O3, 5% FetO3, 2% MgO, 4% CaO, 4% Na2O, and 0.1% S. Thirty seven trace metals are reported including Ba, Cu, Mn, Sr, V, Zn, and Zr. A change in the chemical composition of the ash as a function of distance from the volcano is related to a similar change in physical characteristics of the ash. Water soluble components were also determined after column leaching experiments were performed. Concentration levels of soluble salts were found to be moderately high (1500‐2000 µg/g) with molar ratios suggesting the presence of NaCl, KCl, CaSO4, and MgSO4. Heavy metals such as Cu, Co, Mn, and Zn were found at appreciable concentrations (10‐1000 µg/g). Unexpectedly high concentration levels of ammonium (45 µg/g) and nitrate (100 µg/g) ions as well as dissolved organic carbon (130 µg/g) were observed in several ash leachates. Results for fluoride and boron show low average levels of ∼5 and ∼ 0.5µg/g, respectively.

The current definition of samarskite-group minerals suggests that ishikawaite is a uranium rich variety of samarskite whereas calciosamarskite is a calcium rich variety of samarskite. Because these minerals are chemically complex, usually completely metamict, and pervasively altered, their crystal chemistry and structure are poorly understood. Warner and Ewing (1993) proposed that samarskite is an A 3+ B 5+ O 4 mineral with an atomic arrangement related to a-PbO 2 . X-ray diffraction analyses of the recrystallized type specimen of ishikawaite and the Ca-rich samarskite reveal that they have the same structure as samarskite-(Y) recrystallized at high temperatures. Electron microprobe analyses show that the only significant difference between samarskite-(Y), ishikawaite, and calciosamarskite lies in the occupancy of the A-site. The A-site of samarskite-(Y) is dominated by Y+REE whereas the A-site of ishikawaite is dominantly U+Th and calciosamarskite is dominantly Ca. Additionally, a comparison of these data to those of Warner and Ewing (1993) show that in several cases Fe 2+ or Fe 3+ are dominant in the A-site. We propose that the name samarskite-(REE+Y) should be used when one of these elements is dominant and that the mineral be named with the most abundant of these elements as a suffix. The name ishikawaite should be used only when U+Th are dominant and the name calciosamarskite should only be used when Ca is the dominant cation at the A-site. Finally, because of the inability to quantify the valence state of iron in these minerals, the exact nature of the valence state of iron in these minerals could not be determined in this study.

A new method of analysis for rocks and soils is presented using laser ablation inductively coupled plasma mass spectrometry. It is based on a lithium borate fusion and the free-running mode of a Nd/YAG laser. An Ar/N2 sample gas improves sensitivity 7x for most elements.Sixty-three elements are characterized for the fusion, and 49 elements can be quantified. Internal standards and isotopic spikes ensure accurate results. Limits of detection are 0.01 //g/g for many trace elements. Accuracy approaches 5% for all elements. A new quality assurance procedure is presented that uses fundamental parameters to test relative response factors for the calibration.Geological samples are often cited as among the most difficult materials to analyze because of their wide composition range and complex mineralogy. These minerals vary in nearly all physical and chemical parameters including size, hardness, composition, and solubility. Trace elements may reside within various minerals, may be a major element of a trace mineral, or may exist as a combination of both.An elemental analysis of rocks is important to classify the type of rock and to determine its origin and economic value. Historically, the determination of trace and minor elements in granitetype rocks has depended on a host of analytical techniques including the following: instrumental neutron activation INAA,1,2 energy-dispersive and wavelength-dispersive X-ray fluorescence spectrometry3-6 inductively coupled plasma atomic emission and mass spectrometry (ICP-AES, ICPMS),1 234567•8 910*and atomic absorption spectrometry.910 As a consequence, many elemental ratios used for petrogenetic modeling are calculated using data from different analytical techniques and subsamples.Most ICPMS methods involve dissolving the sample either with acids or fusion prior to instrumental analysis. lithium borate fusions are popular because all major elements and many trace elements can be determined following dissolution of the fusion (

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