Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

K. C. Sahu ¹, R. P. Gurav ¹

Affiliations
1 Indian Institute of Technology, Bombay, IN

Abstract

In the course of study of the Precambrian sedimentary iron ore deposits of Noamundi in Singhbhum district of Bihar and of Goa, extensive occurrences of powdery iron ores known as Blue Dust have been observed and examined. Field features like the nature of occurrence, textural, structural, and mineralogical character of the Blue Dust have been observed in detail. Shape and size analysis of the mineral grains of the powdery ore have been made and their chemical, X-ray and DTA data presented to explain the mineralogy and chemistry. Etch tests and dissolution experiments have been carried out on standard ore pieces at different pH and temperature for different lengths of time to produce material equivalent to the powdery iron ore. From the above data and experiments, and with the theory of anisotropic dissolution of hematite, the mechanism of formation of the Blue Dust has been explained.

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K. S. Balasubramaniam ¹, V. Panchapakesan ¹, K. C. Sahu ¹

Affiliations
1 Indian Institute of Technology, Bombay, IN

Abstract

The homogenisation studies of gas-liquid fluid inclusions in fluorites from Handev Dongar-Ambadongar (Gujarat) and Kahela-Mandokipal (Rajasthan) carried out with a fabricated heating stage corroborates the earlier view that both the deposits are typically of a low hydrothermal origin.

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K. C. Sahu ¹, V. Panchapakesan ¹, R. R. Patil ¹

Affiliations
1 Geology Section, Indian Institute of Technology, Bombay 400076, IN

Abstract

Fluid inclusion studies were carried out on the milky white vein qurtz intimately associated with Kolihan sulphide assemblage. The studies reveal that the deposition should have taken place at a temperature higher than 350°C and the ore-bearing solutions could have had a very high degree of salinity approaching the condition of a 'hydrosaline melt' with 33% NaCI and 17% KCl by weight.

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Satish Degaonkar ¹, V. C. Panchapakesan ¹, K. C. Sahu ¹

Affiliations
1 Geology Section, Indian Institute of Technology, Bombay-400076, IN

Abstract

Copper mineralization in Padar-ki-pal is localised along a N25°E striking phyllite-quartzite contact, transected by three sets of steeply dipping joint planes. Mineralization is in the form of veins, disseminations and permeations of chalcopyrite and other related sulphides. Textures and other related structures reveal the replacement nature of the deposit. Fluid inclusions indicate an aqueous transport of ore elements by a brine undersaturated with respect to highly soluble salts which boiled off at least at the end stage of mineralization. The filling temperature of the inclusions showed signs of entrapment of a homogeneous liquid solution, ranging from 200° to 270°C.

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N. Chennakesavulu ¹, K. C. Sahu ²

Affiliations
1 Nagarjun Sagar Engineering College, Hyderabad, A.P., IN
2 I.I.T., Bombay-400076, IN

Abstract

Olivine is found to have a short range of composition. Orthopyroxenes take up a significant amount of wollastonite molecule in the later stage. Clinopyroxenes show a large scatter in the endiopside-augite field. Fractionation of Fe and Mg among the minerals characterises crystallization from a slowly cooled layered intrusive. The trend of crystallization, of all the three minerals conform to a tholeiitic parentage.

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K. C. Sahu ¹, A. M. Nair ²

Affiliations
1 Indian Institute of Technology, Powai, Bombay 400076, IN
2 Centre of Earth Sciences Studies, Trivandram, IN

Abstract

Chemical study on clean chromites reveals enrichment of chromium and iron due to alteration. Physico-chemical properties show that alteration has enhanced the cell-edge, reflectivity and specific gravity but reduced the microhardness of the mineral. The reemplacement and subsequent instability of tectonic conditions might be the ultimate cause for the shift of Byrapur chromites from aluminian to ferrian field of composition.

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K. C. Sahu ¹

Affiliations
1 Department of Earth Sciences, Indian Institute of Technology, Bombay 400076, IN

Abstract

The basic geochemical principle of coal formation indicates that coal deposits are sinks of a vatiety of toxic heavy metals. Burning of a large amount of high ash coal in a thermal power plant produces a considerable amount of solid waste in the form of ash. Coal ash has been found to have enriched concentration of many of the toxic metals as adsorbed species which on contact with rain water easily leach-out of the matrix only to disperse into various compartments of the ecosystem around the thermal plant. It is suggested that while recognising the deleterious environmental impact of use of a large amount ef high ash coal in thermal plants, precautionary measures should be taken to prevent the entry of the toxic metals into the ecosystem. The ash should be utilized for various developmental purposes.

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K. C. Sahu ¹, D. Venkateswaran ¹

Affiliations
1 Department of Earth Sciences, I. I. T Bombay 400076, IN

Abstract

Weathering experiments have been carried out in laboratory with peridotitic rocks 10 understand the mechanism of mobilization and pattern of dispersion of nickel in vertical profile. Since goethite constitutes the principal mineral constituent in the nickeliferous laterite, synthetic goethite has been precipitated at various pH levels and in presence of varying nickel content in solution. The distribution of nickel in the precipitates has been recognised in terms of crystallinity and particle size of the goethite phase. The observation has been correlated with natural laterite samples collected from vertical profiles of Sukinda lateritic field. It is observed that while the amorphous hydrated iron-oxide has acted as a scavenger of cobalt and nickel from the precipitating solution, the nickel cations tend to inhibit crystallization of goethite. The present finding is considered useful for extraction of the metal from the lateritic matrix.

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H. S. M. Prakash ¹, K. C. Sahu ²

Affiliations
1 No.13A, 1st Cross, Teacher's Colony I Stage, J.P.Nagar Post, Bangalore - 560 078, IN
2 New Indian Mining Corporation Pvt Ltd Nirmal, Central Wing, 16th Floor Nariman Point, Mumbai - 400 021, IN

Abstract

No Abstract.

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D. Narasimhan ¹, N. Krishna Rao ¹, V. Panchapakesan ², K. C. Sahu ²

Affiliations
1 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hydembad - 500016, IN
2 Department of Earth Sciences, Indian Institute of Technology, Powai, Bombay - 400076, IN

Abstract

Fluid inclusion study has indicated two distinct stages of mineralisation: one with higher T_H and lower salinity (greisens) and the other with lower T_H and slightly higher salinity (quartz vein) conditions. These mark the formation conditions of wolframite and scheelite respectively.

Keywords

Economic Geology, Fluid Inclusions, Tungsten, Wolframite, Maharashtra.

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