Abstract
Manganese nodules were found in Java soils which is located in the humid tropical region and influenced by volcanic environment. The objective of this research was to study the mineralogy of the soil manganese nodules developed in the different parent materials. Both samples of manganese nodule and soil were collected from soil profiles developed from limestone (Semanu), tuff-agglomerate (Patuk), and tuff (Cikopomayak). Mineral composition of the manganese nodule was identified with combination of successive selective dissolution and X-ray diffraction. The predominant soil clay mineral in all samples was kaolinite; while in Semanu soil there was also intergrade mineral (Vt-Ch); and vermiculite, illite and Vt-Ch were also identified in Cikopomayak soil. In the manganese nodules, manganese-oxide minerals were almost amorphous minerals and iron-oxide minerals were goethite. Birnessite was only present in Semanu, and Mn was concentrated 23 times in this sample. Some heavy metals were also enriched from the soil to manganese nodule. As for the similarity in the mineralogy of layer silicate on both manganese nodule and soil, it was suggested that the manganese nodules were developed in the soil.
