• M S Sadashivaiah

      Articles written in Proceedings – Section A

    • Chondrodite from the calc-silicate rocks of latehar, palamau district

      M S Sadashivaiah S D Ghosh

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      Chondrodite thus occurs in the forsterite marbles around Latehar. Chondrodite is universally present in this limestone though varying in amount. In characters, occurrence and association, the Latehar chondrodite closely resembles the G-chondrodite of Mansjö Mountain, Sweden, and Glenelg chondrodite of Inverness-shire. The occurrence of Latehar chondrodite as granules and patches partially replacing forsterite-olivine suggests that the chondrodite has been produced by the pneumatolytic metasomatism from forsterite by the accession of fluorine and hydroxyl-bearing fluids from the magmatic liquids which gave rise to the neighbouring granite gneiss of the area. A more or less similar view has been expressed by Read and Double and Eckermann in their study of the Glenelg and Mansjö Mountain chondrodites respectively.

    • Calc-silicate skarns in the granites and gneisses at Jothwad, Panchmahal District, Gujarat State

      M S Sadashivaiah

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      Calc-silicate rocks containing wollastonite, diopside, garnet, scapolite and phlogopite occur in the granites and gneisses at Jothwad, Panchmahal District, Gujarat State. There is some sort of zonal distribution of skarn minerals. Wollastonite is restricted to the limestone granite contact and the diopside, garnet, scapolite and phlogopite are confined to the main skarn zone at the centre. Optical characters of the minerals have shown the triclinicity of wollastonite, diopside (Di63He37), scapolite of the Mizzonite variety, garnet belonging to the spessartite-almandine type and epidote having 20% pistacite molecules. Calc-silicate rocks exhibit variation in grain size and the patchy distribution of the skarn minerals. The formation of the skarn minerals and the various associated features have been brought about by the temperature pressure gradients and diffusion of volatiles and silica during the metamorphism of the limestone due to the granitic intrusion.

    • Winchite from jothwad, panchamahal district, gujarat state

      M S Sadashivaiah C Naganna

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      Chemical, optical and X-ray studies of the blue amphibole, winchite, from Jothwad show that it is a richterite with an affinity to arfvedsonite having the cell dimensions,a=9·65,b=18·12,c=5·25, Å andβ=103° 18′.

    • Aegirine-augite syenite from gundlapalle, guntur district, andhra pradesh

      M S Sadashivaiah K Gowd Reddy

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      Aegirine-augite syenite occurs as small hillocks or dome-shaped mounds around Gundlapalle, Satehnapalli Taluk, Guntur District. It is composed of abundant microclineperthite, subordinate oligoclase, aegirine-augite, occasional ferro-actinolite, katophorite, barkevikite and accessories like calcite, chlorite, apatite, zircon, sphene, fluorite, pyrites and iron ore. Aegirine-augite syenite is an alkaline rock, similar to fenite in its mineral assemblage and it has undergone alkali metasomatism to give rise to the soda amphiboles. Evidences are given in support of the above conclusion.

    • Sphene bearing gneisses of Madhugiri area, Karnataka State, India

      M S Sadashivaiah R S Hanagodimath

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      Sphene fleck granitic rocks (Titanitflecken-gesteine) composed of biotite and migmatitic gneisses are frequently found in the granitic terrain between Madhugiri and Koratagere. The detailed field and thin section studies of these rocks indicate that sphene is formed during the migmatization and feldspathization of the amphibolites, which has resulted in the recrystallization of plagioclase and in the breakdown of hornblende and biotite. The released lime, titania and iron have resulted in the formation of sphene, seen in the gneissic rocks as trains, patches and discrete crystals. Mineralogical, petrological and petrochemical evidences are given in support of the above conclusion.

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