H. C. Verma

Teerthanker Mahaveer University

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R. P. Tripathi

National Institute of Immunology

Chandan Upadhyay

Indian Institute of Technology BHU

N. Bhandari

Graphic Era University

Mamata Mohapatra

Institute of Minerals and Materials Technology

S. Anand

Bharathidasan University

Samar Layek

University of Petroleum and Energy Studies

A. D. Shukla

Physical Research Laboratory

Rudra Pratap Das

Tezpur University

Beena Bhatia

Jai Narain Vyas University

Peter Jenniskens

Search for Extraterrestrial Intelligence

Cooperative Institutions

Jodhpur National University

Jai Narain Vyas University

Indian Institute of Technology Kanpur

Council of Scientific and Industrial Research

Physical Research Laboratory

Institute of Minerals and Materials Technology

Banaras Hindu University

Institute of Materials, Minerals and Mining

University of Rajasthan

Lovely Professional University

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Hyperfine Interactions (2002)

H. C. Verma Chandan Upadhyay R. P. Tripathi A. D. Shukla N. Bhandari

Extinction (optical mineralogy)

10.1023/a:1021232220892

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Citations (6)

Mössbauer spectroscopic studies of the Piplia Kalan (eucrite) and Lohawat (howardite) meteorites

Meteoritics and Planetary Science (2000)

R. P. Tripathi Sanjeev Sharma Kavya Shrivastava H. C. Verma

Abstract— Two meteorites belonging to the howardite‐eucrite‐diogenite (HED) group fell recently in Rajasthan, India. One of these, Piplia Kalan, was classified as a eucrite and the other, Lohawat, as a howardite. In this study, we present the results of Mössbauer spectroscopic investigations of these two meteorites. We also compare the results with the Mössbauer experiments reported for the Kapoeta howardite and look for systematics in the Mössbauer spectra of HED meteorites.

10.1111/j.1945-5100.2000.tb01986.x

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Citations (12)

Ararki (L5) chondrite: The first meteorite find in Thar Desert of India

Meteoritics and Planetary Science (2008)

N. Bhandari S. V. S. Murty P. N. Shukla R. R. Mahajan A. D. Shukla

Abstract— We report here a chance find of a meteorite in the sand dunes of Ararki village of Hanumangarh district in the Rajasthan desert of northwest India. Chemical and petrological evidence in conjunction with isotopic composition of oxygen indicate that it is an L5 chondrite. The fayalite content of olivines is 26.3 mol%. The meteorite has some serpentinized olivines and 0.3% carbon having a terrestrial isotopic composition, indicating that it is moderately weathered. The absence of 22 Na indicate that the meteorite fell to Earth more than a decade ago. The cosmic‐ray exposure age based on cosmogenic 21 Ne is 7.2 Ma. Low density of cosmic‐ray heavy nuclei tracks, low 26 A1 activity, the shielding parameter [( 22 Ne/ 21 Ne) C = 1.094] and absence of neutron capture effects indicate cosmic‐ray shielding in a meteoroid having radius of about 16 cm, implying a meteoroid mass of about 60 kg and ablation of about 93%. The gas retention ages, based on U/Th‐ 4 He and K‐ 40 Ar are 1.1 and 0.58 Ga, respectively, suggesting a heating and degassing event late in the history of this meteorite.

Ordinary chondrite

Parent body

10.1111/j.1945-5100.2008.tb00683.x

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Citations (19)

Thermal decomposition pattern and particle size estimation of iron minerals associated with the Cretaceous‐Tertiary boundary at Gubbio

Meteoritics and Planetary Science (2002)

H. C. Verma Chandan Upadhyay Alok Kumar Tripathi R. P. Tripathi N. Bhandari

Abstract— Mössbauer studies of the samples from the Cretaceous‐Tertiary (K‐T) boundary layer at Gubbio, Italy show that iron appears mainly in two phases, magnetically ordered hematite and a paramagnetic silicate phase. The average particle size of hematite is estimated to be in the range of 16 to 27 nm from transmission electron micrographs and lack of a Morin transition. The hyperfine magnetic field at the iron nucleus is observed to be somewhat less than that of bulk hematite, which may be explained by collective magnetic excitation. Stepwise heating up to 1000°C shows a decomposition pattern of the paramagnetic phase, which suggests it to be a tri‐octahedral layer silicate. The iron‐bearing phases found in the bulk sedimentary K‐T boundary material are different from those found in the spherules separated from this material indicating that the redox conditions changed rapidly after the impact, becoming more oxidizing during the period these bulk phases were formed.

10.1111/j.1945-5100.2002.tb00866.x

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Citations (22)

Systematics of Mössbauer absorption areas in ordinary chondrites and applications to a newly fallen meteorite in Jodhpur, India

Meteoritics and Planetary Science (2003)

H. C. Verma Kavi JEE R. P. Tripathi

Abstract— Mössbauer absorption areas corresponding to 57 Fe in olivine, pyroxene, troilite, and the metallic phase in ordinary chondrites are shown to exhibit certain systematic behaviors. H chondrites occupy 2 distinct regions on the plot of metallic phase absorption area versus silicate absorption area, while L/LL chondrites fall in a separate region. Similar separation is also observed when pyroxene absorption area is plotted against olivine absorption area. The one‐dimensional plot for the ratio of olivine area to pyroxene area separates L and LL chondrites. Based on these systematics, a newly fallen meteorite at Jodhpur, India is suggested to be an LL chondrite.

Pyroxene

Troilite

Chondrule

10.1111/j.1945-5100.2003.tb00290.x

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Citations (55)

Anomalous Mössbauer parameters in the second generation regolith Ghubara meteorite

Meteoritics and Planetary Science (2004)

H. C. Verma R. P. Tripathi

Abstract— We conducted Mössbauer spectroscopic studies on the Ghubara meteorite which had been described as at least two‐generation regolith breccia on the macro scale. The isomer shift and quadrupole splitting of the Fe‐Ni part are quite different from those obtained in ordinary chondrites, reflecting shock effects. We observed a large amount of magnetite that may have come from weathering of, primarily, the silicate fraction. We found very similar iron mineralogy in the Densmore meteorite.

Regolith

Breccia

Ordinary chondrite

Iron meteorite

10.1111/j.1945-5100.2004.tb00071.x

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Citations (20)

Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique

Journal of Hazardous Materials (2010)

Mamata Mohapatra K. Rout Pritam Singh S. Anand Samar Layek

Ferrihydrite

Ammonium bromide

10.1016/j.jhazmat.2010.12.076

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Citations (63)

Implication of Mossbauer Spectra on the Mixing Model of Eucrites and Diogenites (Resulting in Howardites)

Current Science (2015)

Beena Bhatia Kamlesh Patel R. P. Tripathi Samar Layek H. C. Verma

In the present communication, we show that Mossbauer spectra of cumulate eucrites are characteristically different from those of non-cumulate eucrites. In cumulate eucrites, iron occupies only one site, i.e. the M2 site in pyroxene crystal lattice, while it is distributed in both M1 and M2 sites in non-cumulate eucrites. We discuss the importance of asymmetric doublet observed in the Mossbauer spectrum of cumulate body, especially in Vissannapeta cumulate eucrite (fallen in Andhra Pradesh, India), where an appreciable asymmetry was observed. The Mossbauer parameters of diogenite almost exactly replicate those of cumulate eucrites, suggesting that they originate from the same magma ocean. Howardites which are mixed eucrites and diogenites, show iron mineralogy which is different from what one would expect from a physical mixture model. The possible reasons for this difference are also discussed.

10.18520/cs/v109/i2/331-337

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Citations (4)

Lattice sum of electric field gradients in tetragonal crystals

Pramana (1983)

Deepak Verma Arun Kumar Yadav H. C. Verma

Tetragonal crystal system

Lattice (music)

10.1007/bf02846836

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Citations (5)

Classification of the Didwana‐Rajod meteorite: A Mössbauer spectroscopic study

Meteoritics and Planetary Science (2000)

B. S. Paliwal R. P. Tripathi H. C. Verma Sanjay Sharma

Abstract— Mössbauer spectroscopic studies of the Didwana‐Rajod chondrite, which fell on 1991 August 12 in western Rajasthan, India, are presented. The results are compared with the Mössbauer data of several enstatite and ordinary chondrites including the Dhajala chondrite for which Mössbauer data were acquired during the present study. The Didwana‐Rajod chondrite's iron phases and its oxidation states strongly suggest that it should be classified as an H‐type ordinary chondrite instead of the earlier suggestion (based on petrographic studies) that it could be an enstatite chondrite. The present study demonstrates that Mössbauer spectroscopy is a very powerful technique for aiding in the classification of meteorites.

Enstatite

Ordinary chondrite

Chondrule

10.1111/j.1945-5100.2000.tb01444.x

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Citations (28)