Geology and Mineralization of the Toroku Mine, Miyazaki Prefecture

Abstract

The xenothermal-type ore deposits of the Toroku Mine are intimately related to granite porphyry which was intruded during the Miocene. The deposits include two individual ore bodies: the contact-pneumatolytic tin-arsenic ore body found near the granite porphyry and the arsenic-and lead-zinc ore bodies occurring in a breccia zone and formed during high-moderate temperature hydrothermial stages. During a late stage of mineralization, pyrite and marcasite deposition from low-temperature hydrothermal solutions has taken place.
The writer has chiefly investigated the following.
1. Sequence of mineralization.
2. Relation between mineralization and distribution of minor elements.
3. Various textures found in ore minerals such as galena, sphalerite, chalcopyrite and arsenopyrite.
4. Alteration in the country rocks formed during the pneumatolytic to hydrothermal stages.