The mineral composition of the gravity concentrate of uranium ore from Suishoyama pegmatitedeposit, Fukushima Pref. has been determined. Though many rare minerals from this district havebeen described by several authors, it is shown that the only quantatively important ones constitutingthis concentrate are uraninite, samarskite, fergusonite, columbite and wolframite. From the mineralogical composition it is proved that more than 80% of the uranium is contained in uraninite andthe rest is in fergusonite and samarskite.
Magnetic and electrostatic responses of these minerals are given.

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(1) This deposit is an impregnation deposit of sulphur which occurs in both two-pyroxene andesite and the overlying pyroclastic rocks (agglomerate, tuff-breccia and shaly tuff).
(2) The flat shape of this deposit, inclining slightly northwards, depends on the geological structure of host rocks.
(3) The shaly tuff apparently behaved as a cap rock to the mineralizer.
(4) The existence of melnikovite associated with pyrite and marcasite in the ore has been ascertained.
(5) Native sulphur and iron sulphide minerals are impregnated and closely related with each other in host rocks.
(6) The ore usually contains a considerable amount of opaline-clay (clayey substance which consists mostly of opal).

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The Ohe Mine is one of the many manganese mines situated in southwestern Hokkaido.
Geologically, the Ohe Mine area is composed of igneous rocks overlain by Neogene Tertiary sedimentary beds. The former include quartz diorite, porphyrite and basalt; the latter are various green tuffs and felsitic rocks.
The geologic structure is characterized by folds, faults and basaltic dykes which show the same trend as the veins.
The ore deposits consist of many parallel veins which strike about N50°-60°W. The Senzai vein is representative. It pinches at places where it crosses the fault and the boundary of the country rocks, and ore shoots were formed in the upper part of the quartz diorite. This may be due to the fissure system and epithermal conditions. The Senzai vein exhibits successive mineralization of manganese and sulphide minerals. It is divided into three stages and various ore zones as follows;
Stage of mineralization
Ore zone
[I] Sericitization·silicification·quartz vein (1)
…………Sulphide ore (1)
[II] Manganese ore…………Sulphide ore (2)
[III] Quartz vein (2) + manganese ore (2)
The ore zones are formed in units. The lengths of their strike and dip sides are about 30m, and they show typical echelon arrangement.
The constituents of the manganese ore are rhodochrosite, a little rhodonite and siderite. The sulphide ores are pyrite, zincblende, galena and a little chalcopyrite, tetrahedrite and hematite.
It is considered that the above. mentioned minerals are respectively characterized by the various stages of mineralization, especially siderite which forms a solid solution with rhodocrosite and increases in relative amonmts in the later stage of mineralization. Considerable amounts of native gold are found only in the sulphide ore of the latest stage.

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Yellow earth, called Ôdo, is found abundantly in some limonitic iron-ore beds of marshy type. The "Ôdo" contains up to 50% iron. It consists mainly of yellowish fine crystals of goethite, 0.5-1.5μ in size. Small amounts of kaolin minerals, qnartz, feldspar, cristobalite, etc. in the Ôdo have been identified by differential thermal analyses and X-ray powder studies.
From the field data and paragenetic studies it may be concluded that the Ôdo is the product of colloidal precipitation of iron hydroxide together with kaolin and other fine grained minerals in marsh areas.
The iron hydroxides constituting the Ôdo may have been deposited complex oxidation of iron sulphate solutions, while compact limonitic ores were probably formed by biochemical processes.

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The pre-Tertiary basement rocks underlying the coal-bearing strata in the Jôban Coalfield often form buried hills. The development of workable coal seams has been markedly influenced by the existence of the buried hills, in that, the main coal seams. tend to become less thick towards the hills and thin out over the hills. These geological features are important in economic prospecting.
The present writer has recently determined that the following two characteristic features are of outstanding importance.
(1) Many kinds of pre-Tertiary schists such as amphibolite and amphibolite schist, together with the associated hornblende biotite granite, biotite granite, etc., arranged subparallel to the strike of the schists, as observed at their outcrops form the high buried hills.
The birth of the buried hills seems to have no relation to any hidden fault scarp in the basement rocks, but seems to have resulted from the differential susceptibility to erosion among granitic rocks, schists and the metamorphic rocks of the contact zones.
(2) Near the buried hills, large major faults are often accompanied by various kinds of minor faults which were formed by the influence of the buried hills.
They are classified as follows:
(i) minor normal or reverse faults; (ii) minor faults not cutting the basement rocks; (iii) faults and slips along the bedding planes; (iv) minor faults disappearing in the beds; (v) faults with a varied throw along their trends; (vi) faults curved around the buried hills.

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An empirical method of estimating the calorific value and ash content of fresh coal from the analysis of weathered outcrop coal is introduced. The method should be, of course, fully discussed through theoretical treaties on coal-weathering. This is, however, based on many actual data from the analyses of weathered and fresh coal, and may serve to estimate the quality of coals that have only their weathered outcrops in the field. The method is briefly stated as follows:
1. Assumption of the moisture of fresh coals. Approximate value of the moisture can be obtained from the analyses of relatively fresh coals that are in a horizon near to the coal seam in question and are exposed in streams or fresh cuttings.
2. The relation of moisture and calorific value, both on an ash-free basis, of a series of outcroping coals in different stages of weathering is represented in graphs, e.g. Fig. 1. From the graph of the coal in question the calorific value (ash-free) of the fresh coal may be estimated. The graph of a coal in a near horizon or in the same group may be adopted when the data are poor.
3. The relation of moisture (ash-free) and ash content of coals in various stages of weathering, both in the ratio to those of fresh coal, may roughly be graphed as Fig. 2. From this graph the decrease in ash content of the weathered coal is roughly estimated, and the ash content of the fresh coal may be assumed.
4. From 2 and 3 the approximate calorific value of the fresh coal can be obtained.

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