Industrial minerals in Indonesia are widely distributed although in some cases the deposits are not sufficiently abundant to be exploited in large scales. The Directorate of Mineral Resources (f'ormer-Ly the Geological Survey of In• donesia)• is assign.ed to conduct mineral exploratior.. and has a long experience on the matter. This paper discusses in a brief outline some of the Indonesian Industrial minerals, namely bentoni t e, zeoli te, kaolin, ceramic raw materials, diatomite, dimension stones and precious stones.

Almost all of the bentonites in Indonesia belong to the bleaching grades, the deposits occuring in Jawa and being exploited are in Bo jongman i.k, Leuwiliang, Karangnungga L, Nang• gulan and Punung. The deposits are mostly derived from de• vitrification of the Miocene vitric C-rhyo).itic- tuffs) by alterations, ei~her diagene~ic or hydrothermal. Bentonites formed by diagenetic alterations are the'most common occurence in Indonesia. The reyolitic tuffs in many cases .ar-e f'ound, in••., the Tertiary basins, this includes the basins of Sumatra, Kalimantan and Sulawesi. The natural zeolite derived from diagenetic alteration of rhyolitic tuffs are very widely distributed, but they have not been exploited and utilized yet.

Kaolin in Indonesia occur mostly in the granite belts of Bangka, Biliton and West Kalimantan. The deposits are derived from the Jurassic granitic rocks, either by hydro• thermal alteration or redeposition of rewor-kang of weathered granites within the Quaternary sedimentary rock formations. Generally the Indonesian kaolins belong to the ceramic grades, although some of them are paper filler grades, i.e. kaolins of Biliton. However, the lower grade kaolins may be found elsewhere and they are derived from alteration product mostly volcanic rocks such as andesites, volcanic breccias and tuffs.

Tidak tersedia versi lain

Tidak Ada Data