Perpustakaan Digital ITB

The Gosowong gold mining area is located in the north central part of Halmahera Island, Indonesia. There are three deposits in the Gosowong mining area; Gosowong deposit, Togurachi deposit and Kencana deposit. Kencana deposit is located in the southeast part of the Gosowong mining area, and was found in 2003. Kencana deposit is composed of three veins (K1, K2 K-Link). In the Gosowong Mining area, there are four formations; the Bacon Formation, the Gosowong Formation, the Kayasa Formation and the Quaternary Volcanic Formation. Gosowong Formation is composed of Tabobo Sandstone and Gosowong volcaniclastics, in which Gosowong volcaniclastics are composed of coherent volcanic and volcaniclastics rocks. The Kencana veins exist in the Gosowong volcaniclastics Formation. The deposit is classified as a low to intermediate sulvidation Au-Ag epithermal deposit, In the Kencana deposit, ore minerals are chalcopyrite, electrum, hessiz petzite, galena, low Cd-bearing sphalerite and high Cd-hearing sphalerite. Gangue minerals are composed of quartz, calcite and adularia. The Au content of electrum is different from each vein, and is generally high. Sphalerite can he separated into 3 groups, The highest Cd group is from 33 at. % to 40 at. %. The contents of Cd depends on the environment at the time of formation.