The Journal of the Geological Society of Japan

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Rorei Iron Ore Deposit is located in Tohendo, Tsuka Province, Manchoukuo along the summit of the Rorei mountain, about 30 km., northwest of Rinko( ?? ?? ) on the bank of the Oryokko River( ?? ?? ?? ), being an iron ore bed at the basal portion of Sininan Quartzite (Fe: 30∼40%), showing irregular enrichment (Fe: about 60%), on Utai crystalline dolomitic limestone., The ore body is divided into the reddish and greenish coloured sandstones forming cross beddings and the latter alters to the former gradually and irregurally., The green sandstone contains quartz and very minute scally iron chloritic minerals near aphrosiderite by the chemical analysis., The red sandstone contains quartz and hematite or reddish coloured chloritic minerals; the hematite is recrystallized in the silicified part penetrated by very narrow quartz veins., In the reddish coloured altered part of the green sandstone at the contact with quartz veins, the percentages of Fe^··· and Si increase, that of H₂O+ decreases and the total amount of Fe is almost constant, comparing to those values in the adjacent green part., It is shown from these facts that the oxidation of Fe^·· and the loss of H₂O+ were brought about by the heat action and the silicification by penetrating quartz veins., On the other hand in the reddish coloured gradual altered part in the green sandstone, much increase of Fe^··· is always recognized, being contained as hematite, and the iron chloritic mineral is replaced by hematite mainly in this part as shown by X-ray powder photographs., The temperature of a quartz vein was determined as about 250°C∼300°C, from the degree of the oxidation of Fe^·· (the ratio ; Fe^···/Fe^··) in the reddish coloured altered part adjacent to the quartz vein by the comparison of the specimens to the heated pieces of the green sandstone at 200°, 300°, ····, 1000°, 1100°, 1200°, 1300°, and 1400°C, in the electric furnace., In the green sandstone some carbonate minerals were found as the recrystallized mass of very minute cleavage flakes, (indicating a secondary sideritic phase after dolomitic by the partial alteration) replacing the chloritic mineral in part., (As an experiment, X-ray powder photographs were taken with the heated pieces of the thuringite from Dairishiko Iron Ore Deposit, and found that the alteration of thuringite to hematite takes place at about 1000°C., ) The ore deposit was formed by the primary deposition of hematite and iron chlorite and the alteration of the iron chlorite partly., According to the previous data, the action of meteoric water heated by igneous rocks that is hot springs, may be the most powerful factor for the leaching of iron from such iron chloritic minerals.,

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