Popigai
The impact that turned graphite into a field of diamonds.
Key facts
- When
- about 35.7 million years ago
- Where
- Northern Siberia, Russia
- What hit
- an asteroid perhaps 5 to 8 km across
- Era
- Deep time
- Location
- 71.65° N, 111.20° E
Probably around 10 million megatons of TNT, possibly more.
About a tenth of the Chicxulub impact.
What happened
Popigai in northern Siberia is one of the largest impact craters on Earth, about 90 to 100 km across. It formed in the late Eocene, when the world was warmer than today but slowly cooling.
The asteroid struck rock that contained graphite, a soft form of carbon. The shock pressure, far higher than anything in Earth's crust, turned the graphite instantly into diamond. The crater holds a vast quantity of these impact diamonds, mostly tiny and mixed with a related mineral called lonsdaleite. They are too small and impure for jewellery but very hard, and they were long kept secret in the Soviet Union.
Chemical traces in the melt rock suggest the impactor was an ordinary chondrite.
Effects
Popigai struck within about a few hundred thousand years of the Chesapeake Bay impact. Together they mark a time of more frequent large impacts, but they did not cause a major extinction, although the climate cooled over the following few million years.
The evidence
Shocked minerals, impact melt rocks, the diamonds themselves and the crater's ring-shaped structure.
Did you know?
Impact diamonds form in a fraction of a second, while ordinary diamonds take millions of years deep in the Earth.
The crater was found in 1946, but it was only recognised as an impact structure in the 1970s, when its shocked rocks and diamonds were studied.
Related pages
How is impact energy measured? See energy explained, or try the impact calculator.