For quantitative analyses of trace elements in rock samples by inductively coupled plasma-mass spectrometry (ICP-MS), it is necessary to accommodate instrumental drift and irregularities in detector linearity. Interferences of oxide molecular ions and non-spectral matrix effects are also taken into consideration to establish an appropriate analytical method. Relatively rare trace elements in rock samples, such as rare earth elements, are determined by alternatively analyzing a 10-ppb standard solution and 1000 times diluted rock solutions containing a 10-ppb Indium internal standard. Analytical results for both samples and standards are normalized to the internal standard, which enables minimization of instrumental drift and correction of uncertainty in dilution factors. Using the internal standard, matrix effect is effectively canceled out at the dilutions factor. Determinations of elements present in relatively high concentrations, such as Rb, Sr, Y and Zr, is achieved by increasing dilution to achieve acceptable detector linearity. This further suppresses matrix effects originating from concomitant major elements.
According to the recommended nomenclature for zeolite minerals by the subcommittee on zeolites of the Commission on new minerals and mineral names of IMA (1997), 83 species have been defined. After the recommended report, three new zeolites have been approved in the Commission up to the date. Though gmelinite-K was recorded in the zeolite report of 1997, it was formally approved in 1999. Here, all 85 spicies are summerized and the 41 species among them found in Japan are briefly reviewed.
Valid identification of microinclusions, which is essential to understanding the genesis of minerals, can require more than traditional petrology that is focused on their chemical compositions. By combining determination of chemical composition with X-ray characteristic imagery of atoms, electron microprobe analysis of individual microinclusions provides a means by which to identify their chemical structures or mineral species. Here we apply this technique to identification of microinclusions and show the results obtained substantiate the origins of colors for sunstones: A transparent red-color of the Oregon sunstone is due to the distribution of mixtures of both native coppers and cuprites in oval-shaped thin films, while the transparent-green type is due to the distribution of their similar mixtures in short microcolumns.
Electron back-scattering diffraction (EBSD) is a unique tool to obtain crystallographic information from specimens in a scanning electron microscope (SEM). Crystalline phases, crystal orientation and the relationship between the crystal orientation and morphology of the specimens are readily determined by analyzing Kikuchi patterns with dedicated software. Several applications in mineralogy, where EBSD combined with SEM imaging is very useful and convenient, are described.