The manganese oxide phases are often metastable, intimately intergrown with other materials, and so poorly crystalline that attempts to identify them by conventional X-ray diffraction techniques are brought with difficulties. The fundamental structure unit in manganese (IV) oxides is the [MnO₆] octahedron which are linked by corner-sharing and edge-sharing to give a variety of chain, tunnel and layer structures. Initial data on the hydrogen isotopic composition in hydrous manganese minerals from various occurrences fall in a wide range from -298 to -84‰ relative to SMOW. Hydrogen isotope fractionation factors between manganite and water were experimentally determined to be 0.7894, 0.7958 and 0.8078 at 150, 200 and 250°C, respectively. This experimental results indicate that if manganite were formed at temperatures below 250°C, under isotopic equilibrium conditions, most of the manganite mineralization in the Tertiary manganese deposits must have precipitated from meteoric hydrothermal solutions. The manganese ores in the Cretaceous formation of northeastern Hokkaido are characterized by low Fe/Mn ratios. The trace element concentrations and REE patterns are similar to those of the submarine hydrothermal manganese deposits. Distribution patterns of trace elements (Co Ni Cu and Zn) and REE in the manganese oxide ores of this area are of two types: (1) hydrogenous deposits which have relatively high concentrations and (2) submarine hydrothermal deposits which have low concentrations.

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The alunite-natroalunite solid solution series were synthesized by precipitation from mixed solutions of K₂SO₄, Na₂SO₄, and Al₂ (SO₄)₃ for 2 days' reaction at boiling temperature. The K ions in the initial solution were preferentially taken into structure during crystallization of the alunite, and amounts of products formed in this reaction decreased with decreasing K mol% of the solution. The calculated structural formulae on the basis of SO₄=2 indicate that the synthetic alunites contain H₃O ions in the A sites, which increased from 11 to 19 mol% with decreasing K mol%. In addition, the slight deficiency of Al ions suggests the presence of vacancies in the B sites. Structural changes of alunites were observed by the thermal treatment. At 530°C, formation of KAl (SO₂)₂ from alunite and Al₂ (SO₄)₃ from natroalunite occurred simultaneously with the removal of OH ions. Removal of SO₄ ions from the dehydroxylated phases led to formation of amorphous phases at about 803°C for alunite run and about 765°C for natroalunite run. The amorphous phases then recrystallized into K₂SO₄ and Al₂O₃ in the alunite run and Na₂SO₄ and Al₂O₃ in the natroalunite run. The thermal behavior suggests the existence of compositional immiscibility between alunite and natroalunite.

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A new thermodynamic model for ternary solid solutions has been derived from the statistical mechanics using a Bragg-Williams approximation. In the model, interaction energy among three closest neighbours (triplet) is considered instead of that between two closest neighbours (pair). According to the model, the excess molar Gibbs energy of mixing can be expressed as follows:G^ex=X_AX_B(X_AW_AAB+X_BW_ABB)+X_BX_C(X_BW_BBC+X_CW_BCC)+X_CX_A(X_CW_CCA+X_AW_CAA)+2X_AX_BX_CW_ABC, where X_i denotes a mole fraction of i component and W_ijk is an interaction parameter. This model has the consistent interaction parameters (W_AAB, W_ABB, W_BBC, W_BCC, W_CCA, W_CAA) with those for the Margules-type asymmetric binary solution model, and gives them physical meanings. The model can be extended to the n component systems. Supposing interactions among r closest neighbours, the number of interaction parameters (N_w) for the model is expressed as

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Weathering products in a brown soil (sample S3) and in a partially weathered antigorite in yellowish brown color (sample A59b) were collected from the serpentinite zone in Sasaguri area, Fukuoka Prefecture, Japan. The products were studied by X-ray diffraction, transmission electron microscopy, analytical electron microscopy, infrared absorption spectrumand differential thermal analysis. Mineralogical composition of the brown soil are 14Å intergrade, halloysite, goethite and ferrihydrite associated with Si, and hematite. Si-containing goethite, Si-containing ferrihydrite, hematite and hisingerite were found in the weathered antigorite. The results suggest that leaching of Mg and Si from the serpentine minerals occurred at initial weathering stages. Precipitation of hydrous iron oxides and hydrous iron silicates may occur after the leaching of Mg and Si. Poorly crystallized iron minerals showed aggregate of microcrystalline materials (<100Å). The result suggests that the 14Å intergrade and halloysite were produced from weathered chlorite and/or mica minerals in the crystalline schist, or weathered chlorite in the vein at the serpentinite zone, or 2 : 1 layer silicates in eolian dust.

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From the later half of the nineteenth century to the early twentieth century, the progress of mineralogy had brought about more complete descriptions of many crystalline objects. During the period, endeavors to express three-dimentional crystal forms as precice as possible were begun by use of projections on a plane. Since then, the endeavors have developed a uniqe method as “the drawing of crystal forms” based on “the clinograhic projection” which prescribes a certain fixed relation between view point (the direction to project) and crystal axes. This drawing can be made with Wulff's net construction of an axial cross, or the calculation of zone axes (Parker's method), etc. Although crystal drwings with this method make it possible to understand three-dimensional crystal forms at a glance, the method has been less frequently used because it requires annoying procedures or troublesome calculations. Recently, such obstacles are ovrcome with the help of personal computer or handy calculater, and crystaldrawings can be more easily done. This paper reviews “the drawing of crystal forms” and explains the concrete procedure of drawing of crystal and twin forms.

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It is difficult to decipher the phase equilibrium of synthetic amphibole at low temperature, because of the sluggishness of reaction. The phase equilibrium is recomfirmed by the reversal run and the uniform composition of the run product. However, some problems remain, even if the experiments are considered to be close to representing equilibrium. One of problems is that Na and Si are dissoved in the coexisting water under the higher pressure than 10 kbar. Consequently, the bulk composition of synthetic amphibole must become nonstoichiometric, and the amphibole coexists with other phases in the field where amphibole alone should be a stable phase. The stability field of amphibole against temperature becomes smaller with increasing water content. For example, the composition of the synthetic pargasite shifts to the tremolite composition. Another problem is that the triple chain silicate is contained in the amphibole synthesized at low pressure (∼3 kbar) and low temperature (∼800°C) under excess water condition. The triple chain bearing amphibole might be confused with amphiboles, if the electron microprobe analyses were considered alone. It is also difficult to distinguish a few triple chain bearing amphibole from amphibole by X-ray powder diffraction patterns. Nevertheless, the stability and the phase relationship of the triple chain bearing amphibole are still not well understood. Further evidence for the triple chain bearing amphibole will be verified by high resolution electron microscope (HREM) and the experimental study.

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Novel porous materials have been developed in order to utilize industrial solid wastes. Fly ash-gypsum-portlandite system (FGL) and Kuroko mining waste-gypsum-portlandite system (KGL) were investigated. The mining wastes should be processed at 500-900°C beforehand. Many varieties can be prepared according to mixing proportions. Precursors were firstly made from slurries by moulding. Hemihydrate or anhydrite was used as gypsum source to facilitate short period consolidation. Then, the precursors were steam-cured for 24h under 80°C and 90% R. H. condition after demoulding. Two parageneses of hydrates were observed, i.e., ettringite and C-S-H, and gypsum and C-S-H. Physical properties are dependent on water/solid weight ratio, W/S. Present porous materials have a potential of practical use for building materials as heat insulators. Bulk densities of 0.66 and 0.62 g/cm³ and thermal conductivities of 0.15 and 0.14 kcal/m.h. °C have been reached as minimum values for FGL and KGL, respectively, without any bubbling agent.

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A computer software package, CRYSTAL UTILITY, is presented for the description of crystals. CRYSTAL UTILITY includes the programs for drawing crystal structures, calculating x-ray powder diffraction intensities, calculating lattice constants of a crystal using the least-square method and drawing crystal shapes. These programs are written in a BASIC language using the NEC PC-9801 series personal computer. One who is not necessarily a specialist in crystallography can use CRYSTAL UTILITY without a special knowledge of a computer or a computer language.

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