It's always great to go back home to Texas. I get to visit with my parents and eat chicken-fried steak. And in recent years, I've been able to show the kids the family moon rock.

Yeah, a moon rock. I was in college when my father got it at a NASA dinner 20 years ago. Dad, who served his coastal Texas district as a state senator from 1960 to 1981 and answers to the nickname "Babe," never made a big deal of the rock. He placed it in a cluttered display cabinet, alongside the reproduction of a doodle by JFK (No. 184 of 500), near a block of wood salvaged from a platform on which LBJ spoke in Pasadena, Tex., in November 1964, and not far from the desk set given to him by John Connally in 1966 to commemorate Dad's ceremonial stint as Texas's "Governor for a Day."

As you can imagine, even a moon rock can get lost in that kind of hodgepodge. I hadn't paid much attention to it for years. Then, on one of the recent big family get-togethers, I heard my kid brother tell his daughter to "put the damned moon rock down"--as if she were about to damage something valuable. That's when I gave it a serious once-over.

It looked, basically, like a rock. Shiny, a little pitted, it stood on a post that was stuck into a pedestal bearing the following inscription:

Apollo 11 Volcanic Basalt Fragment

On July 20th, 1969, for the first time, man stepped forth on the moon. The crew of the "Eagle" collected lunar rock samples and brought them to Earth for scientific research. This black volcanic basalt fragment (no. 10022) weighed 96 Earth grams. Its bubbly texture is a result of red hot volcanic magma cooling to a solid and entrapping lunar gases. It is symbolic of the scientific results of Apollo which displaced speculation with tangible knowledge. The technological and scientific achievement of the Apollo program stands as one of man's greatest accomplishments.

The front of the pedestal sported a small bronze plaque that read:

AIAA Banquet

10th Anniversary

First Manned Lunar Landing

Houston, 20 July 1979

The acronym stands for American Institute of Aeronautics and Astronautics, the professional society for the aerospace field.

The idea that we actually owned a moon rock suddenly filled me with a sense of awe--and a sense that Dad might have a plentiful retirement fund sitting in the cabinet. So I started checking it out. But the more research I did, the stranger things seemed.

Occasionally, moon bits from Soviet missions come to earthly markets; Sotheby's got more than $400,000 for three at a 1993 auction.

But American moon rocks are kept under tighter control by NASA, and the occasional offers of them generally turn out to be scams. In 1995, brothers Brian and Ronald Trochelmann of Atlanta persuaded the New York auction house Phillips Son & Neale to put a fist-sized rock collected by the Apollo 12 crew up for auction. They said John Glenn gave it to their late father in recognition of food-processing technologies that he developed for NASA. None of it proved to be true. The brothers sought millions; instead, they earned themselves an indictment. The two men pleaded guilty to fraud charges last year and are awaiting sentencing.

Then there's the case of Peggy Davis, who recently tried to put fragments of what she said was moon dust residue up for sale. Her sales agent has estimated that the tiny bits of "lunar detritus" could fetch $1 million. Davis's father had been a NASA electrician, and according to their family story, the specks were molded into a gob of plastic and put into a plastic desk set--a retirement gift from his colleagues when he left the Lunar Receiving Laboratory in Houston in 1970. Davis, an Oregon child-welfare worker, said the agency threatened to sue her if she tried to sell it. NASA denied that, but seized the set. Earlier this month the agency, which took a PR beating after newspaper and television reporters told Davis's story, announced that it was giving the desk set back to Davis. The agency's scientists said they doubt that the thing contains any actual moon dust, anyway.

News stories like those put a damper on my idea that my folks might strike it rich with our rock. The stories noted that federal law and NASA policies prohibit the third-party distribution of moon stuff. Only a limited number of rocks ever left the space agency, officials said, and then only little "diplomatic samples" given to foreign heads of state and dignitaries. The reports even made me wonder whether what Dad had really was from the moon: Again and again in the stories, NASA spokespersons claimed to know where each lunar fragment in the world could be found.

But I still held out hope that maybe, just maybe, we had the real thing. Dad's district had included the environs of NASA's Johnson Space Center outside of Houston, and he had wrestled a lot of funding into the area. If all politics is local, why not a "diplomatic sample" for a local politician? Why not Babe Schwartz?

And if you can't trust NASA and the AIAA, whom can you trust?

I didn't know how to penetrate the bureaucracy of NASA to find out the truth. But I had a potent ally in my quest: My buddy Kathy Sawyer, who covers the space agency for The Post. Kathy, who is kind to small children and patient with fools, agreed to find out about our little No. 10022.

It took months of phone calls, official requests and Freedom of Information Act submissions. Aptly named NASA publicist Stella Luna said flat out that the rock could not possibly be real. But Kathy kept digging--and finally got on the phone with Gary Lofgren, the chief curator of all of America's lunar loot. Lofgren patiently explained to her that he gets a few inquiries like ours every year, but that there was no way the rock could be the genuine 10022.

The rock known as 10022 was one of about 90 samples retrieved from the lunar surface by the crew of Apollo 11--for some reason, NASA started the numbering system at 10000, and collected 2,200 samples over all six moon missions. Each of those rocks has been cut and cut and cut again, so that there are some 110,000 moon chunks out there. As the rocks were sliced up for study, each fragment was given a sub-number: There was 10022,1, 10022,2 and so on. And Lofgren said he knows where each one is.

He checked the records for 10022 and, sure enough: "We have that sample." It had been cut up long ago. Lofgren had done it himself.

Oh.

What we had, he suggested, is one of a smallish number of casts made from the real rocks. "Not many people have those models," Lofgren explained to Kathy. "They should treasure it on those grounds." Thank you, Mr. Pollyanna.

When I called to tell my father what I'd learned, he was angry--he had believed that the rock was real, and felt that he'd been conned. There was certainly nothing in either inscription that gave it away, though a closer look with new knowledge reveals a bit of fudging in the language used on the plaque.

I reread the words over the Christmas break, on our latest family visit to Texas. I looked at the supposedly precious object again. Its base was cheap plastic. The "rock" now seemed more like resin than basalt. And, even though I've never been very good with the metric system (hey--neither is NASA, har har) I got a feeling that the thing is a quite a bit lighter than 100 grams (about three-and-a-half ounces).

You might be reading this and thinking that we were a bunch of dopes. But it was hope that blinded us. What is hope, anyway, if not a willing suspension of disbelief--a willingness to be tricked? We saw what we wanted to see--and therefore, we owned a moon rock. People have been taken in by a lot less.

I asked my older kids how they felt about the disappointing truth. My son Sam, a worldly 9, took the news in stride.

"Sammy, do you remember this moon rock?"

"Yeah."

"We found out it isn't really real. Did you think it was real?"

"Not really."

My daughter, 12-year-old Elizabeth, was a little more generous--and her comments were eerily like Lofgren's.

"Is it, like, a mold of one?"

"That's right."

"Well, that's pretty good."

So Dad and I gently placed our moon rock back in the cabinet. He pointed out his campaign handouts: the matchbooks, rulers and bumper stickers with slogans like "Be for Babe--Your State Senator and Mine." Close by was the cottonwood twig cut crosswise to display the image of a perfect, five-pointed Lone Star. And there was the little brass plaque we boys gave him when we were kids:

"THE BEST DAD WE EVER HAD"

BOBBY

DICKY

JOHNNY

TOMMY

No longer a wandering piece of the universe, the moon rock was still part of the collective family memory. And it looked perfectly at home among our true treasures.

John Schwartz, who covers technology for The Post, swears he is not as gullible as he might seem.