Geology and sulphur deposit in Uguisu-zawa Mine, situated in the northwestern district of Hanamaki, Iwate Prefecture, Northaest Japan, are described and some considerations on the ore genesis are mentioned. This sulphur deposit consists of some layered ore seams intercalated in mud stone which were formed in the depression caldera of small scale relating genetically to the “Kuzumaru Volcano” already reported. This sulphur deposit has been believed to be the “Lake Deposit Type” but it is more reasonable to consider that it belongs to the “Flowed Sulphur Type” from theviewpoint of the structural and textural features of the ore seams.
