A massive meteorite believed to be the largest piece of Mars ever discovered on Earth has been sold for $5.3 million, inclusive of taxes and fees, to an anonymous buyer during an auction at Sotheby’s in New York.

The rare specimen, named NWA 16788, weighs approximately 24.5 kilograms (54 pounds)—significantly larger than typical Martian meteorites, which are usually found as much smaller fragments. According to a statement from Sotheby’s, NWA 16788 is roughly 70% larger than the second-largest known Martian meteorite.

The rock was found in November 2023 in the remote Agadez region of Niger. Experts have hailed it as a “monumental specimen” and a “once-in-a-generation find,” due to its extraordinary size, distinctive red hue, and rarity—only about 400 Martian meteorites have ever been discovered on Earth.

“This is the largest Martian meteorite ever found, and the most valuable of its kind ever offered at auction,” said Cassandra Hatton, Sotheby’s Vice Chairman of Science and Natural History. “Its weathered surface and unmistakable red color offer a tangible connection to the red planet.”

Scientific analysis suggests the rock was blasted off the Martian surface by a powerful asteroid impact, which melted parts of the rock into glass. A glassy crust formed on its surface as it passed through Earth’s atmosphere before landing.

While the meteorite’s sale excited collectors and space enthusiasts, some scientists voiced concern over its privatization.

“It would be a shame if it disappeared into the vault of an oligarch,” said Steve Brusatte, a paleontology professor at the University of Edinburgh. “It belongs in a museum, where it can be studied and appreciated by the public.”

However, others pointed out the important role collectors play in advancing planetary science. Dr. Julia Cartwright, a planetary scientist at the University of Leicester, noted that the market for meteorites incentivizes their discovery, which ultimately benefits research.

“If samples weren’t being found and traded, we wouldn’t know as much as we do,” she said. “While it would be wonderful to see this incredible rock displayed publicly, I’m hopeful the new owner will still make it accessible for scientific study.”

A reference sample of NWA 16788 has been preserved at China’s Purple Mountain Observatory, ensuring that researchers retain access to part of the specimen.

This sale far surpasses previous records. In 2021, a smaller Martian meteorite containing atmospheric samples fetched $200,000 at Christie’s—well above its initial estimate of $30,000 to $50,000.

The final destination of NWA 16788 remains unknown, but experts say its scientific value is far from lost.