ORE GEOLOGICAL STUDY OF BANDED IRON FORMATION OF DALLI BLOCK (JHARANDALLI MINE), DALLI-RAJHARA, CHHATTISGARH, INDIA

Abstract

The Jharandalli Iron Ore of Bastar Craton, India, is composed of high grade Hematite ore. hosted within Banded Iron Formation (BIF). Iron Ore is sandwiched beteen Quartzite and Shale. Several types of Iron ores have been seen. The area is defoniied and megascopic and microscopic studies supports this point. The genesis of iharandalli iron ore may be of Supergene modified Hydrothermal alteration. Presence of Martite, Diffuse 1-leniatite, Specularite, leaching of silica etc. in the microscopic studies reveals the theory of Supergene modiefied hydrothermal deposit. The Protore or the Protolith of the ore was BIF (BI-IQ). Microscopic studies reveals that the original iron phase was Magnetite. Through low temperature hydrothermal alteration followed by supergene enrichment the BIF has been converted into several types of ores like Hard Laminated. Soft friable Ore, Massive ore, Blue Dust. Lateritic ore etc. Higher grade of hematite is found due to residual upgradation of hydrous iron oxide to hematite. The subsequent leaching of Silica and precipitation of Iron produces Hard Laminated. Soft Laminated is being produced when there is no or little iron precipitation. Acidic ground water circulation produces Blue Dust. The nature of the hydrothermal fluid is not known.