An ordinary rock, in the dark.
An L6 chondrite drifting in the asteroid belt. Olivine, pyroxene, feldspar, metal. Nothing unusual, and nothing that records anything deeper than where it sits.
Shock metamorphism, IIT Kharagpur
Every impact leaves a record. I read it.
I am Dr. Kishan Tiwari. Inside ordinary chondrites there are veins a hundred microns wide that were molten for a few milliseconds, at pressures found 660 kilometres beneath your feet. They are the only samples of the deep Earth anyone will ever hold.
- Position
- Institute Postdoctoral Fellow
- Lab
- Experimental Petrology, IIT Kharagpur
- Samples
- Katol, Kamargaon, Bori, Lonar
Scroll to descend
The person under the microscope
A geologist, a poet, a photographer,
and a serious person who admires
the comedy of life.
I grew up in Mughalsarai, Uttar Pradesh, and finished school there. Delhi came next, a B.Sc. (Hons) in Geology at Hansraj College, then an M.Sc. at the University of Delhi. The Ph.D. followed at IIT Kharagpur, in Earth and Planetary Science, where I am now an Institute Postdoctoral Fellow in the Experimental Petrology Lab.
My work is question-driven, not technique-driven. The instruments, FIB-TEM, FEG-SEM, FE-EPMA, Raman, are how I get an answer, never the reason I ask. What I want to know is what happens to a mineral in the few hundred milliseconds when an asteroid hits another asteroid, and what that tells us about the deep Earth we cannot reach.
Meteorites are leftovers from the formation of the solar system. They kept the original chemistry that Earth spent four and a half billion years destroying.
Longer term I want to build an independent shock-metamorphism and high-pressure planetary mineralogy group in India, wired directly into ISRO's planetary mission roadmap. Indian falls like Katol, Kamargaon and Bori are world-class samples. They should be studied here.
Why the gold bar
The monogram is KT twice over: my initials, and the K to Pg boundary. The golden bar is that iridium-rich clay layer, 66 million years of ordinary rock interrupted by one afternoon. The asteroid at the top is the cause, and the reason I have a job.
What I actually study
A shock wave crosses it in microseconds.
Two bodies meet at kilometres per second. The wave sweeps through the rock far faster than the rock can respond, and pressure climbs into the tens of gigapascals.
Friction along fractures melts it in place.
Where the rock slips, it heats. Thin dark veins of melt open along those surfaces, carrying fragments of the host rock with them.
Minerals collapse into denser forms.
Olivine becomes wadsleyite, then ringwoodite. Pyroxene and feldspar follow. These are the minerals of Earth's transition zone, growing inside a rock you can hold.
It cools before it can forget.
The vein quenches in milliseconds and freezes the whole sequence in place. That frozen moment is my entire subject.
The evidence
A mineral from the lower mantle,
found in a rock that fell on Maharashtra.
In 2021 we reported natural Fe-bearing aluminous bridgmanite in the Katol L6 chondrite, in PNAS. Bridgmanite is the most abundant mineral in the Earth by volume and it is stable only below about 660 kilometres. Nobody has ever sampled it in place.
Everything I do follows from that. Identify the phase, measure its composition, model how fast it could have grown, and the vein gives up the pressure, the temperature and the duration of an impact that happened before the Earth had oceans.
The transformation sequence I look for
Olivine
(Mg,Fe)2SiO4 · below 410 km
The starting material. Ordinary chondrite bulk mineralogy, unshocked and orthorhombic.
Wadsleyite
β-phase · 410 to 520 km
First collapse. Same formula, denser packing. Marks the top of the transition zone.
Ringwoodite
γ-spinel · 520 to 660 km
Deep blue, spinel-structured. In Katol it grew from a superheated chondritic melt, my 2025 paper.
Bridgmanite
(Mg,Fe,Al)SiO3 · below 660 km
Earth's most abundant mineral. We found natural Fe-bearing aluminous bridgmanite in Katol, PNAS 2021.
Publications
Five peer-reviewed papers.
Scroll sideways. Each card opens its DOI.
Evidence for shock-induced transformation and incipient melting of pyroxene in impact-melt bomb from Lonar Impact Crater, India
Tiwari, K., Ray, D., Misra, S., & Arora, G.
Journal of Asian Earth Sciences · 301, 106997
Open DOI →
2025
Olivine to ringwoodite transformation in Katol meteorite: implications for localized superheating of chondritic melt and seismic attenuation
Tiwari, K., Ghosh, S., Miyahara, M., & Ray, D.
Progress in Earth and Planetary Science · 12, 81
Open DOI →
2022
Vesicular olivines and pyroxenes in shocked Kamargaon L6 chondrite: implications for primary volatiles and its multiple impact history
Tiwari, K., Ghosh, S., Miyahara, M., & Ray, D.
Journal of Geophysical Research: Planets · 127, e2022JE007420
Open DOI →
2021
Natural Fe-bearing aluminous bridgmanite in the Katol L6 chondritePNAS
Ghosh, S., Tiwari, K., Miyahara, M., Rohrbach, A., Vollmer, C., Stagno, V., Ohtani, E., & Ray, D.
Proceedings of the National Academy of Sciences · 118(40)
Open DOI →
2021
Shock-induced incongruent melting of olivine in Kamargaon L6 chondrite
Tiwari, K., Ghosh, S., Miyahara, M., & Ray, D.
Geophysical Research Letters · e2021GL093592
Open DOI →
Full list
Citations and preprints live on Google Scholar and ResearchGate.
Selected conference abstracts
- Tiwari, K., Ghosh, S., Miyahara, M., & Ray, D. (2019). High-pressure polymorphs in Katol L6 chondrite: deciphering thermal history and shock conditions. Geophysical Research Abstracts, 18592.
- Ghosh, S., Tiwari, K., Miyahara, M., Rohrbach, A., Vollmer, C., Ohtani, E., & Ray, D. (2019). Natural occurrence of aluminous bridgmanite and its formation in a Katol meteorite. AGU Fall Meeting, DI31B-0015.
- Ghosh, S., Miyahara, M., Tiwari, K., Ray, D., & Ohtani, E. (2018). Formation of Al-bearing bridgmanite in a Katol meteorite. AGU Fall Meeting, P53G-3068.
Collaborators
Nobody images a hundred-micron
melt vein alone.
INDr. Sujoy GhoshAssistant Professor, Geology and GeophysicsIIT Kharagpur
INDr. Dwijesh RayAssociate Professor, Planetary Science DivisionPRL Ahmedabad
JPProf. Masaaki MiyaharaAssociate Professor, Advanced Science and EngineeringHiroshima University
JPProf. Eiji OhtaniProfessor Emeritus, Earth and Planetary Materials ScienceTohoku University
INGarima AroraScientific Officer C, Planetary Science DivisionPRL Ahmedabad
DEDr. Arno RohrbachSenior Researcher, Institut für MineralogieUniversität Münster
DEDr. Christian VollmerResearcher, Institut für MineralogieUniversität Münster
ITProf. Vincenzo StagnoAssociate Professor, Earth SciencesSapienza University of Rome
The record
Read it the way you would read
a stratigraphic section.
Education
- 2023Ph.D., Earth and Planetary ScienceIIT Kharagpur, advisor Prof. Sujoy Ghosh
- 2012 to 2014M.Sc. GeologyJubilee Hall, University of Delhi
- 2009 to 2012B.Sc. (Hons.) GeologyHansraj College, University of Delhi
- 2007 to 2009High School and Intermediate, CBSEKendriya Vidyalaya, Mughalsarai
Fellowships, grants and qualifications
- 2023PRL Ahmedabad Postdoctoral Fellowship
- 2021AGU Student Travel Grant, USD 1,000
- 2021International Travel Grant, IIT Kharagpur
- 2021-22Teaching Assistantship, Geology and Geophysics, IIT Kharagpur
- 2018-21UGC Senior Research Fellow, IIT Kharagpur
- 2016-18UGC Junior Research Fellow, IIT Kharagpur
- 2016CSIR JRF, All India Rank 35
- 2015UGC JRF, All India Rank 33
- 2014-17GATE qualified four times, best score 585
On the road
Conferences, posters, engines.
AGU Fall Meeting in New Orleans, seminars at home, and the one afternoon at NASA Stennis where the hardware is bigger than the science.
In the press
When a mineral from 660 km turns up
in a rock that fell on a field.
The Indian ExpressHow an Indian meteorite helped study Earth's formationGhosh et al., PNAS 2021 →
The HinduScientists find a mineral seen in the depths of the Earth in a meteoriteGhosh et al., PNAS 2021 →
The HinduStudy on meteorite provides clues to Earth's mantleTiwari et al., GRL 2021 →
India TodayAssam meteorite offers clues to how the Earth formedTiwari et al., GRL 2021 →
Off the microscope
The same habit as petrography:
get very close, and wait.
Species names below are my reading of the frames. Corrections welcome.
Birds
Macro
Contact
Samples, collaborations, students,
or an argument about shock stage.
- Phone
- +91 74790 24014
- Post
- Experimental Petrology Lab, Department of Geology and Geophysics, IIT Kharagpur, West Midnapore 721302, India
- Profiles
- Google Scholar