Primary ore minerals of bedded manganese ore deposits in Japan

1.层状锰矿床的原生矿物本学期研究的锰矿床如下：秩父阶地的上佐谷矿、长崎矿和三久保矿;美浓阶地的犬山;丹波阶地的八谷矿、芦谷矿和寺岛矿。结果表明，层状锰矿床的原生矿物为菱锰矿、锰铁矿和黑锰矿。矿石多呈条带状结构，似层状结构，少数呈菱锰矿球状结构。中国元古界高原瓦房子锰矿的原生锰矿物为菱锰矿和二氧化锰，常呈球状结构。世界高原大型矿床的原生矿物也与瓦房子矿相似。锰矿石结构的合成锰矿石的原生结构以条纹状和球状结构为代表。用凝胶法可以很容易地合成这种织构。以菱锰矿和锰氧化物矿物为原料进行了实验研究，通过锰离子在含二氧化碳离子的凝胶中扩散合成菱锰矿，反之亦然。结果，获得了具有径向织构和由球晶组成的条纹织构的球晶。在含氢氧化钠的凝胶中，通过锰离子的扩散，也合成了氧化锰矿物。获得了与菱锰矿相同的结构。然而，球形颗粒显示出同心纹理。研究结果表明，锰矿石原生结构的形成既有沉积作用，也有扩散作用。

1. Primary minerals of bedded manganese ore deposits The manganese ore deposits studied in this term are as follows : Kamisagaya mine, Nagasaki mine, and Mikubo mine in the Chichibu Teraine ; Inuyama in the Mino Teraine ; Yatani mine, Ashitani mine, and Jido mine in the Tamba Teraine. As a result, the primary minerals of bedded manganese ore deposits have been clarified to be rhodochrosite, bementite, and hausmannite. The ores show commonly a striped texture like to lamina and rarely a spheroidal texture by rhodochrosite. The primary manganese ore minerals from the Wafanzi mine on the Proterozoic plateau in China are rhodochrosite and manganese dioxide minerals, and show often a spheroidal texture. The primary minerals from the big ore deposits on plateau in the world are also similar to those of the Wafanzi mine.2. Synthesis of manganese ore texture A primary texture of manganese ore is represented by striped and spheroidal textures. The textures have been easily synthesized by the gel method. Experiments have been performed as to rhodochrosite and manganese oxide mineral. Rhodochrosite has been synthesized in gel containing carbon dioxide ion by diffusion of manganese ion, and vice versa. As a result, the spherulite with a radial texture and a striped texture composed of spherulites have been obtained. Manganese oxide minerals have been also synthesized in gel containing sodium hydroxide by diffusion of manganese ion. The same texture as those of rhodochrosite have been obtained. The spheroidal particle however shows a concentric texture. In conclusion, the present results suggest that the primary texture of manganese ore is formed not only by sedimentary process but also by diffusion process.