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Mookherjee, A.
- Rare Minerals from Rajpura-Dariba, Rajasthan, India 1: Owyheeite
Authors
1 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, IN
2 Institute of Geology of Ore Deposits, USSR Academy of Sciences, Moscow 109017, RU
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 21, No 9 (1980), Pagination: 417-424Abstract
Owyheeite is reported for the first time from an Indian ore deposit. Optical properties, microhardness and X-ray powder diffraction data of the mineral are furnished. Microprobe analysis yields the formula Pb4.76(Ag1.59CU0.11)h0.70Sb6.54Sl5.32. Comparison with other available microprobe data of samples from different localities indicates nonstoichiometric composition of the mineral phase. A small amount of copper seems necessary to stabilize the mineral, since it could not be synthesized in the system PbS-Ag2S-Sb2S3. Curved nature of lamellar grains and existence of spindle-shaped deformation (?) twins imply pre- or syn-tectonic crystallization of the mineral.
- Ore Mineralogy and Fluid Inclusion Characteristics of Different Ore Associations from Malanjkband Copper Deposit, M. P. (India)
Authors
1 Department of Geology and Geophysics Indian Institute of Technology, Kharagpur 721302, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 37, No 3 (1991), Pagination: 239-256Abstract
Textural and paragenetic study of primary minerals (chalcopyrite, pyrite, magnetite, hematite, sphalerite, bornite, chalcocite and molybdenite) reveal intermittent fracturing, precipitation and dissolution phenomena with at least two recognizable stages: magnetite(I) - pyritc(I) - molybdenite (?) followed by pyrite(II) - chalcopyrite - sphalerite - magnetite(II) - hematite - bornite - chalcocite. Oxidation and supergene enrichment effects producing cuprite-malachite-native copper and chalcocite-covellite are moderate. Difference in the mineralogy of the oxidation zone and restricted occurrence of supergene enrichment are due to the variation in the primaty mineralogy of the ore.The ranges of fluid inclusion homogenization temperature (maxima 160°-180°C) and fluid densities in the reef quartz and ore bearing vein quartz are more or less the same, with a wider range of salinity in the vein quartz ores. However, mixed aqueous carbonic inclusions are restricted to the vein quartz ores and hence points towards a difference in the fluid regime. Th vs. salinity and Th vs. density plottings rule out simple cooling and/or mixing processes in the evolution of the fluid but rather hint at immiscible two-fluid phase separation. The suspected presence of low temperature Iss-phases and the results of fluid inclusion microthermometty point towards an unexpectedly low temperature environment of ore deposition. The paragenetic sequence is suggestive of an increase in the Cuffe ratio and fluctuating fO2 conditions in the fluid during the main stage of mineralization.