On the Exploration of the Fukazawa Kuroko Deposits in the Hokuroku District

Abstract

The Fukazawa kuroko deposits were discovered in the central part of the Hokuroku district by a systematic drilling work in 1969 to 1971. Since 1965 we have investigated the stratigraphy in the area by means of detailed geologic mapping and micro-fossil analysis. A concrete exploration work has been planned and carried out successfully based on the geologic information obtained and comparison to the geologic environment of other kuroko deposits such as those at the Kosaka and Hanaoka mines.
The area is occupied largely by volcanic rocks and pyroclastics of the Miocene age, which are divided into four units named Menaichizawa, Yukisawa, Kagoya and Shigenai formations in ascending order. The ore deposits consist of three main orebodies and several small ones. The orebodies are stratiform in general and occur at the top of the Yukisawa formation. Each orebody is composed of black ores and subordiante amounts of yellow ores, siliceous ores, and gypsum ores.
In the mine the production of crude ores was commemced in the rate of 10, 000 tons per month in November, 1973, and will be increased to 15, 000 tons in October, 1974.