NEW YORK (AP) — Up for sale is a 54-pound (25-kilogram) rock with an estimated auction price of $2 million to $4 million. What makes it so valuable? It’s actually the largest piece of Mars ever discovered on Earth. Sotheby’s in New York is set to auction off this rock, known as NWA 16788, on Wednesday, as part of a natural history-themed sale that also includes a juvenile Ceratosaurus dinosaur skeleton, standing over 6 feet (2 meters) tall and almost 11 feet (3 meters) long.
According to Sotheby’s, this meteorite is believed to have been ejected from Mars by a massive asteroid impact, then traveled 140 million miles (225 million kilometers) to Earth, where it crashed into the Sahara Desert. Discovered by a meteorite hunter in Niger in November 2023, the red, brown, and gray rock is approximately 70% larger than the next biggest piece of Mars found on Earth, making up nearly 7% of all Martian material on our planet. Measuring nearly 15 inches by 11 inches by 6 inches (375 millimeters by 279 millimeters by 152 millimeters), it’s a significant find.
Cassandra Hatton, vice chairman for science and natural history at Sotheby’s, described the Martian meteorite as an extraordinary discovery, doubling the size of the previously largest known piece of Mars. Only 400 Martian meteorites have been found out of over 77,000 officially recognized meteorites on Earth, making this rock even more unique.
After a piece of the meteorite was sent to a specialized lab and confirmed to be from Mars based on its chemical composition, experts identified it as an “olivine-microgabbroic shergottite,” a type of Martian rock formed from magma cooling slowly. With a glassy surface likely caused by the intense heat during its entry into Earth’s atmosphere, the meteorite is a remarkable piece of interplanetary history.
Also featured in the auction is a juvenile Ceratosaurus dinosaur skeleton discovered near Laramie, Wyoming, in 1996. Believed to be from the late Jurassic period, approximately 150 million years ago, this skeleton is estimated to fetch $4 million to $6 million. Standing out for its resemblance to the Tyrannosaurus rex but smaller in size, the Ceratosaurus dinosaurs could grow up to 25 feet (7.6 meters) long.
The auction, part of Sotheby’s Geek Week 2025, will include 122 items ranging from meteorites and fossils to gem-quality minerals.
