Two obsessions gripped Edgar T. Ingalls until the day he died. One was that riches could be found beneath the soil near his Potomac home. The other was that people should be made aware of the fight to pull those riches from the ground.

His grandsons, brothers Byron and Darrel Ricketts, share the second obsession.

That’s why we’re in a massive warehouse just inside the Beltway in Prince George’s County. It’s a repository for National Park Service artifacts. Arranged on a table are items the brothers haven’t seen for 40 years. They’re relics from the Maryland Mine, a long-shuttered gold mine near Great Falls where their grandfather was the foreman.

There are ore samples. There’s a set of brass weights to weigh precious metals. There’s a large round bell that was used to signal shift changes — unless it signaled when the elevator was emerging from the mine shaft. (The brothers can’t remember.)

Gold was discovered near Great Falls in the mid-19th century. It was deep, and it was petulant. To get it out, miners went as far as 300 feet down and blasted, picked and chiseled away at rock. Tons of stone were sent to the surface to be crushed in powerful mills. The crushed ore was mixed with mercury to draw the gold from the powdered stone.

How much gold was there? Just enough. But when FDR froze the price of gold at less than $40 an ounce during the Depression, the mine was no longer profitable. It closed in 1940.

“He always dreamed that they would reopen the mine someday,” Byron said of his grandfather.

They didn’t, so Ingalls directed his gold fever in a different direction. He opened a little museum to the mine in his Potomac home, eventually building an addition to his house and opening it to the public on weekends. His wife, Marie, painted scenes of mine life. There was mine equipment on display, gold-flecked ore samples (locked in a safe each night) as well as artifacts from previous inhabitants: Civil War buttons and swordblades, Indian arrowheads.

In 1960, Ingalls published a pamphlet on the mine, its history, its operations. His family had owned a farm not far away, and he’d started at the mine as a teenager. His pamphlet is laced with the optimism of the gold-obsessed. “As far as real mining goes, the surface of this tremendous ore deposit has just been scratched,” he wrote. “The horizontal drift on the 200-foot level has been extended only 175 feet south and 200 feet north on the vein.”

With the right investors, the right men, the right equipment. . . .

Ingalls never had the chance. Although he and son Huntley would do occasional prospecting — they shipped 20 ounces of gold to the U.S. Mint — Edgar went to work at the Dalecarlia water treatment plant.

In 1971, Ingalls prepared to move to North Carolina. He didn’t want to break up his museum and was happy when the Park Service stepped in and bought the collection for $6,000. His dream was that the Park Service — the mine is in the C&O Canal National Historical Park — would put the collection on display.

It didn’t, and that left his family a little teed off. For awhile, the collection sat in boxes in the basement of Great Falls Tavern. It was moved to Sharpsburg, Md., then Springfield. Today, it’s at the Park Service’s Museum Resource Center in Landover. Ahna Wilson, a Park Service C&O Canal historian, arranged for some items to be pulled for the brothers to see.

“Our family’s always wondered what happened to it,” Darrel said of the collection.

Some bits — miner’s helmets, prospecting pans, crucibles — are at a gold mining museum at Monroe Park in Fauquier County. The rest is here. There isn’t money to put it on display, and Great Falls Tavern is the last place it should go: It’s in a flood plain.

The brothers worry that some artifacts might have disappeared over the years — they remember an old rifle and a large chunk of ore shot through with gold (“If there’s anything that might walk, it’s gold,” Byron said) — but it could just be that they haven’t been catalogued yet.

If anyone got rich working the Maryland Mine, it wasn’t Edgar T. Ingalls, who died in 1974. “Our mother said they were never poorer than when he was working at the mine,” Byron said.

Said Darrel: “He died poor, basically. He always contended there was much more down there.”