Abstract
Ring ores occur in many volcanic sulphur deposits which are mainly composed of iron sulphides. These ring ores can be classified into two types, lava type and shale type, on the basis of their mode of occurences and structural characters.
Lava type is widely found, and it has been reported that such ores were formed by the Liesegang´s phenomenon.
Aaccording to the present studies it can be believed that these rings were formed by the replacement along the onion-like cracks.
The shale type is found rarely, and it seems that these rings were formed by the inward diffusion of the reacting solution.
