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Agate Rock Turns Out to be Dinosaur Egg

Agate? You mean eggate.

A pretty pink and white agate sitting in the Natural History Museum, London’s Mineralogy Collection since 1883 has turned out to be even more stunning than thought for a surprising reason. Around 15 centimeters (6 inches) across, almost completely spherical but otherwise unassuming, the specimen has remained in the collection for the last 175 years, until a chance finding earlier this year revealed it to be a dinosaur egg.

Dinosaur egg that resembles an agate rock
Credit: Trustees of the Natural History Museum, London

The specimen's attractive interior colors caught the eye of Robin Hansen, one of the Mineral Curators at the NHM who helped prepare the specimen when it was selected to go on display in 2018. Then a trip to a mineral show in France helped reveal the significance of the “rock”.

'While I was looking around the show, a dealer showed me an agatised dinosaur egg, which was spherical, had a thin rind, and dark agate in the middle. That was the lightbulb moment when I thought: 'Hang on a minute, that looks a lot like the one we've just put on display in the Museum!'"

The specimen was originally collected in India and the size, shape, and surface features are the same as those of other specimens of titanosaur eggs from China and Argentina. The egg is thought to date back to 60 million years ago when titanosaurs were the most common dinosaurs living in India.

"This specimen is a perfect example of why museum collections are so important," explained Hansen. "It was identified and cataloged correctly as an agate in 1883 using the scientific knowledge available at the time."

"It is only now that we have recognized that this specimen has something extra special – the agate has infilled this spherical structure, which turns out to be a dinosaur egg."

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