Preliminary experiments on the accuracy of inclusion gas analysis with a quadrupole mass spectrometer (QMS) were carried out. Quantitative analysis of gases with a QMS is made by utilizing the two kinds of data; the intensity of the major peak for each gas and a factor called sensitivity of QMS (=major peak intensity/pressure of gas introduced in the QMS). The sensitivity is instrument-dependent. Since the amount of gas released from a natural sample may vary from sample to sample, the following instrumental factors must be examined prior to applying a QMS to inclusion gas analysis. (1) Cracking pattern for each gas does not change with pressure. (2) Sensitivity of the QMS does not vary with pressure. It was observed that the pattern coefficients of CH4, N2, CO2, and C2H6 do not change in the pressure range from 1×10−3 to 1×10−5 Pa. The slight variation in sensitivity with decreasing pressure was observed for Ar, N2, CO2, CH4, C2H6 and H2. However, the relative sensitivity (i.e., sensitivity for each gas/that for N2) for each gas is almost constant in the pressure range from 5×10−4 to 2×10−5 Pa, with the exception for H2. The multi-component working standard gas was analyzed by using the pattern and sensitivity coefficients obtained in this study. The results are in good agreement with the data obtained by gas chromatographic analysis except for H2. However, it was observed that the concentration of H2 of the multi-component standard gas increases whereas that of CO2 decreases with the progress of successive analyses. This phenomenon is due to the results of mass discrimination during the introduction and evacuation of the gas.
This paper describes a method of quantitative reflection color analysis for minerals and whole rock using an image scanner and a general use personal computer. The scanner obtains true color (24 bits) digital images of polished rock surfaces. The software, Wilber, that has been developed for the present project, analyzes the color bitmap information of the area indicated manually by the operator and calculates mean value and standard deviation of RGB, HSB, XYZ, and x-y parameters. Mineral and whole rock colors are generally weak (low saturation) and highly heterogeneous (high hue dispersion) in comparison with artificial objects, animals, and plants. This makes rock color measurement technically difficult, especially in the case of coarse-grained plutonic and metamorphic rocks. To solve the problem, hundreds of trial-and-error experiments have been performed, arriving at the following recommendations. The best optical resolution of the scanner for mineral color and whole rock color analyses is, respectively, 150 dpi (dot per inch) and 75 dpi. The x-y chromaticity diagram, H-S circular diagram, H parameter, and S parameter are convenient to express the measured mineral colors. The RGB color system is not recommended for this use because of strong random reflection effects. By means of S parameter (saturation) of whole rock color, ornamental and semi-ornamental rocks are classified into high-color (S>10.0), middle-color (8.0<S<10.0), low-color (6.0<S<8.0), slight-color (4.0<S<6.0), and grayscale (S<4.0) groups. B parameter (brightness) is efficient for quantitative color evaluation of the grayscale rocks. Using this parameter, they can be subdivided into black (B<25), dark gray (25<B<55), light gray (55<B<85), and white (B>85) groups. The standard deviation of B parameter may represent color hardness for gray granitic rocks. For evaluation of the high-, middle-, and low-color rocks, the H parameter (hue) is recommended. They can be classified into red (0°<H<20°), orange (20°<H<40°), and yellow groups (40°<H<60°). Sodalite syenite and charnockite are classified to be grayscale rocks due to their low color saturation. However, it is recommended that they are exceptionally evaluated by S parameter, or color intensity, because the market price is highly related to their color.
Crustal fluids are sometimes trapped in minerals during crystal growth or healing of microcracks. The fluids trapped and completely sealed in minerals are called “fluid inclusions”. A fluid inclusion is considered to be a small closed system after trapping, and the conditions of temperature, pressure and chemistry at fluid-trapping can be reproduced in fluid inclusions by various analytical systems. Microthermometry, chemical analyses and observation on occurrence of fluid inclusions are available for exploration of ore deposits, geothermal and petroleum resources, for studies on thermal histories of sedimentary rocks, for elucidation of origins, formation conditions and processes of igneous and metamorphic rocks, for analyses of paleo-stresses and paleo-climates, and consideration on astronomical events.