1999 Volume 53 Issue 1 Pages 19-28
Ogoya Mine in Ishikawa Prefecture, Japan, is one of the fissure-filling vein type copper deposits in the Green Tuff region. The mine contains pyrite, chalcopyrite, galena and sphalerite. Heavy metal ions dissolveed from abandoned metal-mine are common in waste water pool and stream. In the metal mining area, Fe, Cu, Zn and Cd are releasing from dumping area to the Kakehashi River. The drainage water contains Fe (26.85mg/l), Cu (3.97mg/l), Zn (23.94mg/l) and Cd (0.09mg/l). In this mine, various colored microbial mats (biomats) are grown around the No.6 pit drainage system. Abundant brown biomats covered with green biomats have fixed heavy metals on the drainage channel down the pithead. These biomats are observed by both optical and scanning electron microscopes (SEM). Minerals in the biomat and their chemical compositions were analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and energy dispersive X-ray analyzer (EDX). The reddish biomats fix Cu selectively from drainage water, whereas the dark green biomats fix Fe. Microorganisms, such as bacteria and algae, capture most of heavy metals as Fe- and Cu-minerals in/on the cell. It is clarified that copper and cuprite are formed in reddish biomats, and that goethite and maghemite are formed in the brown biomats.
