Abstrak 
Tin Minerals from the Suttsu Deposit, Southwestern Hokkaido, Japan
Euis Tintin Yuningsih, Hiroharu Matsueda
Universitas Padjadjaran, Proceeding The 10th Hokkaido Indonesia Student Association Scientific Meeting (HISAS 10) Hokkaido University, Sapporo, Hokkaido, Japan February 9, 2013
Inggris
Universitas Padjadjaran, Proceeding The 10th Hokkaido Indonesia Student Association Scientific Meeting (HISAS 10) Hokkaido University, Sapporo, Hokkaido, Japan February 9, 2013
Cassiterite, Mawsonite, Ohkubo, Polymetallic, Stannite, Suttsu
The Suttsu is polymetallic vein-type deposit located in southwestern Hokkaido, Japan. The deposit is hosted by Miocene Kunnui Formation of tuff, tuff breccias and shales. The occurrence of tin minerals such as cassiterite in the deposit is interesting because these mineral is rarely found from Neogene Tertiary period of epithermal base- and precious-metal deposits in southwestern Hokkaido. There were rare tin sulfides minerals identified such as colusite and mawsonite from Shin Otoyo, petrukite (?) and stannoidite from Teine deposits, but not cassiterite. Banded and siliceous ores samples from Ohkubo vein of the Suttsu deposit provided from the Hokkaido University Museum collection were prepared for analyses. Detailed microscopic study and electron microprobe analyses coupled with Back Scattered Electron (BSE)-based image were applied to identify the occurrence of tin and other association ore minerals. Both banded and siliceous ores of Ohkubo vein samples contain the tin minerals such as cassiterite, stannite and mawsonite. Backscatter electron image with scanning electron microscope shows the intergrowth texture of stannite and chalcopyrite. Stannite and mawsonite were probably deposited as a reaction product between cassiterite, pyrite or chalcopyrite with the ore solution. The intergrowth texture also suggested that stannite might be resulted from the decomposition of the Sn-bearing chalcopyrite. Based on Fe and Zn partitioning between co-existing stannite and sphalerite, the tin-polymetallic mineralization in Suttsu occurred at lower temperature (~300°C) comparing to other tin-polymetallic deposits worldwide. These stannite-sphalerite pairs temperature data was slightly higher compared to fluid inclusions homogenization temperature (Th) measurement data of quartz mineral associated with ores (average 202° to 255°C/upper to lower levels). Thus, it was concluded that the tin-polymetallic mineralization in the Suttsu deposit occurred under low temperature conditions. Local and temporary geological conditions were probably the main control favoring the early stage tin-polymetallic mineralization in Suttsu.