The writer studied a Bi-Sb mineral from the Horobetsu mine (Hokkaido) megascopically, microscopically and by etching tests, micro-chemical tests, spot analyses and powder method of X-ray analysis. As a result of the study, the writer obtained the following facts:
1) This mineral has lead-white color and a needle-like crystal habit similar to boih bismu- thinite and stibnite.
2) This mineral occurs in small veinlets in the iron sulphide ore body of the Horobetsu deposit. 3) The optical properties are almost similar to those of bismuthinite and stibnite, but some of them seem to be of an intermediate character between these two minerals.
4) This mineral shows beautiful zonal structure after etching with KCN and KOH solution (Fig. 3). 5) By chemical analysis the writer decided that it had two components of Bi2S3 and Sb₂S₃, and that the value of Bi₂S₃ : Sb₂S₃ was almost 3 : 2 with some variation.
6) The results of spot analyses and powder method of X-ray analysis indicate that this mineral has no parallel intergrowth structure, and that it is a solid-solution of bismuthinite and stibnite.

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The Hayama Mine is situated on the Abiikuma Plateau about 15 kilometers to the southeast of Fukushima City. The district is composed mostly of hornblende biotite granodiorite. However, some hornfels and ultra-basic rocks, such as dunite and diallagite, are present in the form of a roof-pendant. The nickel-bearing minerals, such as niccolite, gersdorffite, pentlandite and nickeliferous pyrrhotite etc., occur as fine grains in the forsterite aggregates, which form a vein-like body in dunite. The forsterite rock is also cut by remarkable black veinlets, composed of the acicular or fibrous crystals of ludwigite. Ludwigite is known to be produced by the chemical reaction of boron- and iron-bearing emanations from granitic magma on some magnesium-bearing rocks such as dolomite and magnesite. Under the microscope, the nickel minerals generally appear in pure crystals, filling up the interstices between the forsterite grains. The niccolite, is rarely rimmed with gersdorffite. Ludwigite is always accompanied by magnetite and chromite which are thought to have been derived from the ultra-basic rock.
The paragenesis of nickel minerals-forsterite-ludwigite-chromite is very critical in the interpretation of the ore genesis. This deposit must be studied from two viewpoints, one from magmatic differentation and the other from contact metasomatism.

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In February 1952 the author published in Japanese a comprehensive treatise on the manganese deposits of Japan as a monograph of 547 pages with 4 plates and 525 text-figures. Some important topics concerning the genesis of the minerals of the manganese deposits are presented in this paper as follows;
(1) Mineralizing solution of manganese. (2) Chemical composition of the solution.
(3) Physico-chemical characters of the solution. (4) Behavior of silica in the solution.
(5) Iron and manganese in the solution. (6) Black substance in the solution.
(7) Alteration of the wall rocks of manganese deposits.
(8) Ore bringer, i.e., an igneous rock most intimately related to manganese deposits in genetical conditions.
(9) Bonanza of the manganese deposit. (10) Manganese dioxide of primary origin.
(11) Fossil Radiolaria and spherulitic carbonate of manganese.
(12) Genesis of the manganese deposit. (13) Geological age of manganese mineralization.
(14) Classification of the manganese deposits.
I. Deposits from a solution not differentiated.
(a) Tomisato Type. (b) Ananai Type. (c) Kitami Type. (d) Ushioe Type.
I'. Similar deposits of other ores from solutions also undifferentiated.
Iron-manganese ore; Red iron ore; Manganiferous iron ore; Brick silica stone.
II. Deposits from a solution moderately differentiated.
(e) Yamato Type. (f) Kaso Type. (g) Manako Type.
III. Deposits from a solution strongly differentiated.
(h) Inakuraishi Type. (i) Numadate Type. (j) Pirika Type. (k) Sambe Type.
III'. Similar deposits from solutions also strongly differentiated. Shizukari Type; Ankerite deposit.
IV. Metamorphosed deposits.
(l) Yakeno Type……contact-thermal metamorphosed deposit.
(m) Muramatsu Type……dynamothermal metamorphosed deposit.
(n) Ioi Type……hydrothermal metamorphosed deposit due to granitic exhalation.
(o) Kawazu Type……hydrothermal metamorphosed deposit due to liparitic exhalation.
(p) Residual deposit……weathering product in situ.
(q) Akiyoshi Type……secondary accumulation of weathering products.

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