Segnitite was found as crusts in association with philipsbornite on fissure of quartz vein including arsenopyrite from the Tohgane mine, Gifu Prefecture, Japan. The representative EDS analysis of segnitite excluding H₂O is; PbO 31.38, Al₂O₃ 5.97, Fe₂O₃ (total Fe) 23.72, P₂O₅ 0.32, As₂O₅ 25.24, SO₃ 4.13, total 90.76 wt.%. This yielded an empirical formula of Pb_1.01(Fe_2.13Al_0.84)_Σ2.97[(AsO₄)_1.60(SO₄)_0.37(PO₄)_0.03]_Σ2 on the basis of As+S+P=2 in anhydrous part. The X-ray powder pattern is indexed on hexagonal cell with a=7.326, c=17.135Å.

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Textures of rocks as well as their chemical compositions have quantitative information on their formation histories. Therefore, it is important to develop common and automatic techniques of the texture description. In this paper, applications of image analyses on the quantitative representation of rock textures were reviewed. Image analyses of rock textures consist of acquisition, processing, and quantitative analyses of images. BSE image has been predominantly used for these procedures, although other kinds of images (e.g. color images acquired by image scanners and microscopes) have been used in recent years. In image processing, binary images are produced by thresholding grey scale or color images, and grains (or grain boundaries) are recognized. This procedure has a crucial role in the following image processing and quantification. Quantitative analyses of mode, grain size distribution, grain shape and other factors of rock textures are carried out based on these binary images. Many algorithms for such quantitative analyses have been developed. In two workshops for image analysis of rock textures organized in 1996 and 1997, several technical problems have been discussed.For example, difficulty in recognizing grain boundaries in rocks is a common basic problem in using any imaging tools. We should also develop new imaging tools such as X-ray CT and NMR imaging to obtain directly 3D data.

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The latest X-ray photoelectron spectroscopy (XPS), employing several devices for better charge neutralization on the mineral surface, provides surface compositional, oxidation state and structural information. This sensitive system functions as a probe to invesitgate the electron binding energy except for photoelectron ejection from H and He atoms. The static charge referencing techniques by several internal standards, the gold decoration, and bridging-masking methods of using electrically conductive adhesive tape or gold wire are sample preparations available for maximizing the neutralization on the surface of non-conducting minerals. Special notice of data treatment is directed to the orbital map drawn by high resolution XPS.

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Electron probe microanalysis (EPMA) of the wavelength-dispersive (WD) type offers some advantage in each quantitative analysis of carbon and nitrogen in non-conducting minerals coated with a thin film of Al-metal and carbon, respectively. The crystal of W/Si evaporated multilayers for long-wavelength WD spectrometry is used to cover the routine wavelength range for these elements. Both opening of the slit and accumulation of the intensity by reiterative measurements at several analytical points adjoining each other have improved the accuracy in the low count rates of 'soft' X-rays from canbon and nitrogen.

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A simple free-dry technique for scanning electron microscopy (SEM) has been applied in observing the morphology of hydrous soil minerals under the state as natural as possible. After the samples are placed in the distilled water, they are dipped into ethyl alcohol, then into t-butyl alcohol, and finally frozen in liquid nitrogen. Completely dried within the vacuum evaporator, the frozen samples are used for the SEM observation.

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　金デコレーション法による粘土鉱物の結晶表面マイクロトポグラフを透過電子顕微により観察する方法と,実際に筆者の研究室で行っている作業手順を示した.ここに記した手順をそのまま実行しても,粘土鉱物の結晶表面に存在するステップに金が選択的に必ず付着するとは限らない.それにはかなり偶然的要因がある,しかし,上述の方法を実行すれば成功する確率は高くなる.実際筆者の研究室では3割の確立で成功している.成功させるキーポイントは試料を加熱する温度である.また,その結果得られた表面マイクロトポグラフにはさまざまなパターンが観察される.それらのパターンが全て成長模様を示しているのではなく,劈開面をはじめとし,積層,結晶どうしの重なりなどによる模様が観察される,それらの模様はしばしば成長パターンとまぎらわしい場合が多い.また,成長模様であっても,成長中心から成長ステップまで全てが完全に観察される場合はまれである.　金デコレーション法により観察される粘土鉱物の成長模様は,ほとんど円形あるいは多角形の渦巻き成長パターンである(Fig.15).しかし,まれに二次元成長を示すと考えられる模様が観察されることもある.デコレーション法による粘土鉱物の結晶成長機構に関しては砂川らの研究グループやBarronnet(1972)によりほぼ解明されている.しかし,粘土鉱物に使用するデコレーション法は結晶成長理論を使った地質学的あるいは資源地質学的問題として粘土鉱物生成環境の解明など,今後ひろく応用分野が期待される.

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A new Imaging Plate (IP) system for transmission electron microscopy (TEM), which has a pixel size of 25μm×25μm, has been developed by Fuji Photo Film Co., Ltd. (1994). In this paper the new IP system is briefly reviewed and tested. The characteristics of the new IP are high sensitivity, wide dynamic range and linear sensitivity compared with those of photographic film for TEM. It is very useful for high-resolution TEM of electron-beam sensitive minerals. Furthermore, digitally recorded TEM images are convenient for image processing.

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