The geology of the manganese ore deposits of talwara,district Banswara,Rajasthan

Talwara (23° 34′: 74° 22′) is a small Manganese-producing locality in the district of Banswara, Rajasthan. From the Banswara Town, Talwara can be reached by a motorable road. In the past, the Manganese ores of the locality have drawn very little attention of the geologists. The ores of Manganese, being associated exclusively with the Aravalli limestone of Rajasthan, occur in the form of scattered masses occupying solution cavities, fissures, etc., in limestone. Aravalli quartzites, conglomerates, phyllites and slates also occur in the vicinity of Talwara. The white limestone with a mosaic structure is of common occurrence and is composed of calcite and dolomite with some magnetite. The impurer varieties of limestone are characterised by the presence of tremolite, hornblende and quartz with a little of biotite. Schistosity is developed only in a calc-amphibole rock having alternating bands of hornblende and limestone. Crush-breccia is noticed occurring in association with manganiferous limestone at a distance of about 2 miles west of Talwara. This breccia might have originated due to severe local crushing of the country-rock. The limestones seemed to be a product of low-grade metamorphism of a calcareous sediment. Fresh ores are generally hard and cavernous but on weathering they become softer and soily. Fragments of unreplaced limestone are occasionally present in the ore-bodies. This limestone has also been replaced by the Manganese ores to a greater or lesser extent, depending on the structural characters of the host rock. The ores are composed largely of massive and colloform cryptomelane. Pyrolusite forms an insignificant part of the ores. There are two generations of cryptomelane, of which, the earlier colloform one is veined by the later generation of cryptomelane. There are also examples of pseudomorphous replacement of limestone by cryptomelane. Most of the pyrolusite was derived from the supergene alteration of cryptomelane. From their nature and mode of occurrence the Manganese ores are classified as outcrop secondary ores formed in cavities in crystalline limestones belonging to the less metamorphosed type of Dharwar.     

Orthogonalized plane wave calculation of the conduction band of CuCl

Calculations of the conduction band of CuCl by OPW method upto 6th neighbouring points in the reciprocal space have been made along three high symmetry directions Δ, Λ, and Σ. The calculated band structure agrees well with the u.v. absorption spectrum.     

The direct electrochemical synthesis and crystal structure of salts of [M4(SC6H5)10]2− anions (M = Zn,Cd)

The salts [(C₂H₅)₃NH]₂[M₄(SC₆H₅)₁₀] (M = Zn, Cd) can be prepared by the electrochemical oxidation of the metal in an acetonitrile solution of triethylamine and benzenethiol. An X-ray crystal structure determination shows that the anion consists of a tetrahedron of metal atoms, each carrying a terminal -SC₆H₅ ligand, and connected to the three other metal atoms by bridging > SC₆H₅ groups. The results are compared with those for similar compounds reported in the literature.     

New classification in the spectra of highly ionized Cu and Zn in the region below 55 Å

The extreme ultraviolet spectra of Cu and Zn are analyzed. New classifications in the wavelength region below 55 Å are tabulated. The spectra were excited by focussing high power laser radiation on plane targets in a vacuum. The spectral lines reported here correspond mainly to the transitions between levels of principal quantum number 3 and 4 in Cu XVI to XIX and Zn XVII to XX. The identifications are based on extrapolations of published data for isoelectronic ions.     

Arylindoles. III. Mannich reaction of 1-arylindoles

1-Phenyl-, and 1-nitrophenylindoles when subjected to Mannich reaction conditions gave the corresponding 3-dialkylaminomethyl derivatives ( IIc-IIk ) in good yields.     

The reflection spectrum of cuprous chloride in the 4.5−30 eV range and the related band structure

The reflection spectrum of CuCl is measured on cleaved monocrystals, at low temperature, up to 30 eV. The main lines of different band schemes, proposed recently by theoretical approaches, are compared with characteristics features in the reflection spectra. All transitions at ?, between the three highest valence bands and the two lowest conduction bands are identified. The observation of transitions where the initial states are in 3sCl^- permits to determine critical points in the conduction bands. With the help of our experimental data we propose a band scheme for cuprous chloride.     

Three Wave Interactions in a Beam-Plasma-System in a Cylindrical Waveguide

Interaction of three waves in a beam-plasma system in a circular cylindrical waveguide is studied. The dispersion relation and the axial growth rate have been obtained.