We report here the occurrence of trapped fluid phases within upper amphibolite and granulite facies minerals in the gneiss-charnockite progression of the Lützow-Holm Bay (LHB) region in East Antarctica. The dominant fluid species in garnet, feldspars and quartz from charnockites comprises dense carbon dioxide, as confirmed by microthermometric experiments and laser-induced micro Raman analyses. The abundance of carbonic inclusions shows as much as five times increase when passing from gneiss to charnockite, suggesting the external influx of carbon dioxide which lowered the water activity through carbonic metamorphism. From the various phase-types of inclusions present in different minerals and their relative chronology of entrapment, we trace the fluid evolution in the LHB from an early high dense pure carbonic regime through mixed carbonic aqueous to a late aqueous regime. The scarcity of aqueous inclusions in the granulite minerals testifies to low P_H2O and high P_CO2 conditions for the crystallization of the charnockite assemblage, which is in keeping with the solid phase equilibria observed in these rocks. Similar findings from granulite terrains in other Gondwana crustal segments suggest that CO₂ advection in the deep crust has been fundamental to the Earth’s crustal evolution history.

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Synthetic fluor-phlogopite, KMg₃Si₃AlO₁₀F₂, was treated by KOH hydrothermal solution under the following conditions: a temperature range from 300 to 800°C, KOH concentration from 1 to 10M, and duration from 3 hours to 216 days under a constant external pressure of 100 MPa. Solid products were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and electron microprobe analyzer (EPMA). The aqueous phase was chemically analyzed.
In the entire range examined, (OH)-rich phlogopite was always produced in addition to the original F-phlogopite. The composition of the newly formed phlogopite varied with temperature and KOH concentration. The compositional gap between the two phlogopites was explained as an apparent immiscibility gap that appears in the temperature-composition section of the three parameter system of temperature, composition, and KOH concentration.
The present study suggests practical conditions for the complete conversion from F- to OH-phlogopite as follows: [KOH]/[F-phlogopite]>8 and a temperature range of 500–600°C.
SEM observations of the experimental products indicated that the F/OH exchange mechanism was not an ion exchange between solid and solution, but rather a dissolution and precipitation reaction in a KOH hydrothermal solution.

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A new mass spectrometer and the associated analytical systems, called HIRU, was designed and constructed for the argon isotope analysis of minerals from young volcanic rocks as well as metamorphics and granitoids. HIRU is composed of a sample holder, an extraction oven, purification lines, standard gas lines, a mass spectrometer, and an ultra high vacuum pumping system. All the parts, except for the sample holder, were made of stainless steel and connected with ICF flanges using Cu gaskets or ultra high vacuum metal valves. The mass spectrometer is a 15cm sector type with an oblique incidence-single focusing system using an electron bombard ion source and three collectors which contain 8 (for ³⁶Ar), 6 (³⁸Ar) and 4 (⁴⁰Ar) stage secondary electron multipliers respectively.
Argon isotope analysis by HIRU is summarized and the precision and reliability of the new mass spectrometric system are discussed in this paper. A series of analysis for argon isotopes, such as taking a set of spectrum, the calculation of isotopic ratios, argon content, and ages is carried out with a computer-controlled system. HIRU has mde it possible to date geological materials with high sensitivity (eg. tens mg of mica of Cretaceous age), high precision (ca. 1% of error for argon content), reliability (possible for rocks older than 0.1 Ma), and convenience (eg. 5–6 samples can be dated per day).

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Toyohaite, Ag₂FeSn₃S₈, tetragonal, I4₁⁄a, a=7.464, c=10.80Å, Z=2, is a new mineral corresponding to the Ag analogue of rhodostannite. Microprobe analyses demonstrate partial substitutions of Cu for Ag and Zn for Fe. The most Ag-rich and poor analyses are: Ag 24.39, 16.31; Cu: 0.14, 5.15; Fe 6.28, 6.18; Zn 0.37, 1.29; Cd 0.22, 0.14; Sn 41.24, 42.01; In 0.05, 0.17; totals 100.86%, 99.65%. They correspond respectively to: (Ag_1.95Cu_0.02)_Σ1.97(Fe_0.97Zn_0.05Cd_0.02)_Σ1.04Sn_2.99S_7.57, and (Ag_1.26Cu_0.68) _Σ1.94(Fe_0.92Zn_0.16Cd_0.01) _Σ1.09(Sn_2.95In_0.01) _Σ2.96S_7.39 (basis: total metal=6). Calculated density is 4.94 g/cm³. Toyohaite has a rhodostannite-like brown reflection color with very weak dichroism and distinct to strong anisotropism. Reflectances are: 23.5–24.3% (480nm); 24.1–26.1% (546nm) 24.7–26.4% (589nm); 26.5–28.3% (650nm). X-ray powder diffraction lines and their relative intensities: 3.72(35), 3.21(100), 2.03(35) and 1.882(35). It occurs as irregular-shaped poly crystalline aggregates up to 200 μm across in a massive pyrite-sphalerite ore from the Sorachi vein of the Toyoha mine, Sapporo, Hokkaido, Japan. The intimate associates include rhodostannite, hocartite, teallite, herzenbergite, and berndtite.

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