Alteration and Exsolution Characteristics of Ilmenites of Moheskhali Island, Chittagong, Bangladesh

Authors

  • Syed Samsuddin Ahmed Department of Geology and Mining, University of Rajshahi, Rajshahi
  • M Yunus Miah Institute of Mining, Mineralogy and Metallurgy, BCSIR, Science Laboratory Road, Khonjonpur, Joypurhat
  • Chowdhury Qumruzzaman Department of Geology and Mining, University of Rajshahi, Rajshahi
  • M Nazim Zaman Institute of Mining, Mineralogy and Metallurgy, BCSIR, Science Laboratory Road, Khonjonpur, Joypurhat
  • AKM Badrul Alam Institute of Mining, Mineralogy and Metallurgy, BCSIR, Science Laboratory Road, Khonjonpur, Joypurhat
  • Pradip Kumar Biswas Institute of Mining, Mineralogy and Metallurgy, BCSIR, Science Laboratory Road, Khonjonpur, Joypurhat

DOI:

https://doi.org/10.3329/bjsir.v45i1.5173

Keywords:

Ilmenite, Rutile, Opaque, Exsolution, Alteration

Abstract

Mineralogical analysis of Moheskhali beach sands revealed the presence of high amount of ilmenite. About 50% of these ilmenites are unaltered which are characterized by the presence of exsolution of ilmenite with hematite, ilmenite with magnetite, and ilmenite with rutile. Others (50%) are unexsolved where 30-50% grains partially or fully altered. These altered and unaltered phases of ilmenite are confirmed by X-Ray diffraction study. Ilmenite-hematite exsolution comprising 70-80% of the total exsolution. The widely banded exsolved phases were formed by continuous exsolution mechanism while the second generation thinner bands were formed discontinuously. Seriate texture dominates (about 75%) over emulsion, granular, quadrangular, sub graphic, veined and special types. Optical study suggests that the alteration of ilmenite is seen to proceed along grain boundaries and/or fractures resulting in an amorphous to microcrystalline mass resembling leucoxene. The chemical composition of the alteration products of ilmenite frequently fluctuates within definite ranges (pseudoilmenite and pseudorutile ranges) of a nonstoichiometric composition and thus deviates from their ideal composition.

Key words: Ilmenite; Rutile; Opaque; Exsolution; Alteration.

DOI: 10.3329/bjsir.v45i1.5173

Bangladesh J. Sci. Ind. Res. 45(1), 17-26, 2010

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How to Cite

Ahmed, S. S., Miah, M. Y., Qumruzzaman, C., Zaman, M. N., Alam, A. B., & Biswas, P. K. (2010). Alteration and Exsolution Characteristics of Ilmenites of Moheskhali Island, Chittagong, Bangladesh. Bangladesh Journal of Scientific and Industrial Research, 45(1), 17–26. https://doi.org/10.3329/bjsir.v45i1.5173

Issue

Vol. 45 No. 1 (2010)

Section

Articles

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