A piece of the planet Mars could be yours for the bargain price of several thousand dollars.

The extraterrestrial artifact and some 350 other offerings will be put up for sale in a simultaneous New York City/Beverly Hills auction this weekend by I.M. Chait, the California auctioneer that is selling the host of natural history specimens. The artifact, which the owners of the auction house said is from Mars, could be either a rock or meteorite from the planet that entered the Earth’s orbit, the owners said.

According to a Web site of the Jet Propulsion Laboratory of the California Institute of Technology, of the 24,000 or so meteorites that have been discovered on earth, only 34 have been identified as originating from the planet Mars. According to the Web site, those rare meteorites created a stir when the National Aeronautics and Space Administration announced in August 1996 that evidence of microfossils may be present in one of the Mars meteorites.

Among the sale’s most unusual lots: the hand of an Egyptian mummy from the Ptolemaic period, a fossilized penguin, several rare meteorites, and a juvenile aquatic reptile dating back 200 million years. That piece of Mars? Auctioneers estimated its value at between $6,500 and $7,500.

This weekend, I.M. Chait also is selling a Tyrannosaurus skull estimated to be 67 million years old, valued between $140,000 and $180,000. “I’m looking at it right now,” auctioneer Josh Chait said yesterday as he unpacked his wares in a rented space on Fifth Avenue. “It’s just a big, scary-looking skull. You can only imagine what the rest of the body looked like.”

The public can preview the items Thursday in advance of Sunday’s sale in New York, which will be telecast to Beverly Hills.

Mr. Chait said the items are expected to generate $2 million or more in sales.

One of the most expensive items, with an estimated price of $250,000 to $300,000, is the largest existing slice of a meteorite with gemstones. “These pieces are quite rare,” he said. “It’s not like they’re making any more of these. You find one, you may not find another one again.”

Industry experts described the market for natural history artifacts as a multimillion-dollar enterprise. “That was not the case 10 years ago. It was just in the domain of science club members, science buffs, amateur astronomer types,” the curator for the Macovich Collection of Meteorites, Darryl Pitt, said. “Now it’s penetrated the art world,” he said. “When you consider the provenance, an outer-space collectible, it’s other-worldly, in terms of its value.”

According to Mr. Chait, whose father launched the auction house about 40 years ago, his company also has seen growing interest from collectors since it entered the market.

Several years ago, I.M. Chait sold a saber-tooth tiger skull from the La Brea tar pits in California for $250,000, the second-highest price for a fossil bought at auction, Mr. Chait said. The highest-priced item, also sold around that time, was a Tyrannosaurus Rex fossil purchased for several million dollars during a Sotheby’s sale.

Still, some scientists argue that historical artifacts belong in museums and research labs, not in private collections.

According to Mr. Chait, “The flip side to that is if there wasn’t a market established and there weren’t collectors, most of these pieces wouldn’t be appreciated. I think eventually most of them will end up in museums anyway.”

Mr. Chait said most of his buyers are doctors, lawyers, and celebrities. “We have new buyers who come in because they happened to see an ad,” he said.

Mr. Chait described a bidding war at an auction last year between two men vying for a dinosaur skull estimated at $50,000. In that case, the winning buyer — a man prompted by his young grandson — outbid a serious collector and paid $150,000 for the skull.

“The grandson told his grandpa that he wanted the dinosaur,” Mr. Chait said. “He’d look at his grandson, and his grandson would nod his head,” Mr. Chait said. “He was a good grandpa.”