Mystery bidder pays $8 million for this rock

The largest piece of Mars ever found on Earth was sold for just over $US5 million ($7.66 million) at an auction of rare geological and archaeological objects in New York, while a juvenile dinosaur skeleton went for more than $US30 million ($45.95 million).

The 25kg rock named NWA 16788 was discovered in the Sahara Desert in Niger by a meteorite hunter in November 2023, after having been blown off the surface of Mars by a massive asteroid strike and traveling 225 million kilometres to Earth, according to Sotheby's.

The estimated sale price before the auction was $US2 million to $US4 million.

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The identity of the buyer was not immediately disclosed. The final bid was $US4.3 million. Adding various fees and costs, the official bid price was about $US5.3 million.

Two advance bids of $US1.9 million and $US2 million were submitted. The live bidding went slower than for many other objects that were sold, with the auctioneer trying to coax more offers and decreasing the $US200,000 to $US300,000 bid intervals to $US100,000 after the proposals hit $US4 million.

The red, brown and grey meteorite is about 70 per cent larger than the next largest piece of Mars found on Earth and represents nearly 7 per cent of all the Martian material currently on this planet, Sotheby's says. It measures nearly 375mm by 279mm by 152mm.

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It was also a rare find. There are only 400 Martian meteorites out of the more than 77,000 officially recognised meteorites found on Earth, the auction house says.

"This Martian meteorite is the largest piece of Mars we have ever found by a long shot," Cassandra Hatton, vice chairman for science and natural history at Sotheby's, said in an interview before the auction. "So it's more than double the size of what we previously thought was the largest piece of Mars."

It's not clear exactly when the meteorite was blasted off the surface of Mars, but testing showed it probably happened in recent years, Sotheby's says.

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Hatton said a specialised lab examined a small piece of the red planet remnant and confirmed it was from Mars. It was compared with the distinct chemical composition of Martian meteorites discovered during the Viking space probe that landed on Mars in 1976, she said.

The examination found that it is an "olivine-microgabbroic shergottite," a type of Martian rock formed from the slow cooling of Martian magma. It has a course-grained texture and contains the minerals pyroxene and olivine, Sotheby's says.

It also has a glassy surface, likely due to the high heat that burned it when it fell through Earth's atmosphere, Hatton said. "So that was their first clue that this wasn't just some big rock on the ground," she said.

The meteorite previously was on exhibit at the Italian Space Agency in Rome. Sotheby's did not disclose the owner.

Bidding for the juvenile Ceratosaurus nasicornis dinosaur skeleton started with a high advance bid of $US6 million, then escalated with offers $US500,000 higher than the last and later $US1 million higher than the last before ending at $US26 million. The official sale price was $US30.5 million with fees and costs. The original estimate was $US4 million to $US6 million.

Parts of the skeleton were found in 1996 near Laramie, Wyoming, at Bone Cabin Quarry, a gold mine for dinosaur bones. It's more than two metres tall and nearly three metres long.

Specialists assembled nearly 140 fossil bones with some sculpted materials to recreate the skeleton and mounted it so it's ready to exhibit, Sotheby's says.

The skeleton is believed to be from the late Jurassic period, about 150 million years ago, Sotheby's says.

Ceratosaurus dinosaurs were bipeds with short arms that appear similar to the Tyrannosaurus rex, but smaller. Ceratosaurus dinosaurs could grow up to 7.6m long, while the Tyrannosaurus rex could be 12m long.

The skeleton was acquired last year by Fossilogic, a Utah-based fossil preparation and mounting company.

Wednesday's auction was part of Sotheby's Geek Week 2025 and featured 122 items, including other meteorites, fossils and gem-quality minerals.

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