The Process of Prospecting Affair in the Ainai Mine

Abstract

The Ainai mine has been operated again after the second world war by finding of black ore deposits. It is located in the northern part of Kazuno basin in Akita Pref., about 6.5km north-west from the Kosaka mine.
The older rocks of this mine are rhyolite, altered volcanic rocks and pyroclastic rocks belonging to the miocene epoch in the Tertiary. These rocks are immediately overlaid or intruded by alteredbasalt. In the western part of this mine, this basalt is overlaid still by the alternations of blackshale, tuff and lava, and they are intruded by dacite and rhyolite.
After their activities, dolerite is penetrated into these rocks by volcanic activity and it is found in all parts of this area.
There are six ore bodies in this mine, and four of them are typical black ore bodies. These ore bodies occur mainly in rhyolite, altered volcanic rocks and pyroclastic rocks. But in exception, they replace altered basalt or dolerite.
The form of them are bedded ellipsoid.
The prospecting affairs are generally drilling, ore sampling, and calculating of grade and tonnage of ore. Besides them, preservation of mine and co-operation with ore-dressing are practiced.