The couple found a surprise historic treasure on their Sierra Nevada property, and it could be worth around $10 million.

Ten paces north of the angular rock on a hill, a rusty can hangs from a tree that marks the spot. More than 100 years ago, someone chose the space below to stash away their fortune — $28,000 in U.S. gold coins. They stayed concealed there, buried in eight tin cans, until John and Mary came upon them last year on their daily walk.

They had struck gold. And when they realized it, the Northern California couple dug a hole in their wood pile, placed the 1,400 coins in bags and boxes in an old ice chest and buried them again.

The pair had walked the path on their gold country property for years before they spotted the edge of a rusty can peeking out of the moss last February. When the lid cracked off, they found dirt-encrusted coins, some in better condition than those on display in museums.

"I looked around over my shoulder to see if someone was looking at me — I had the idea of someone on horseback in my head. It's impossible to describe really, the strange reality of that moment," John said in an interview transcript. The couple, identified by numismatic firm Kagin's Inc., has chosen to remain anonymous — perhaps until they turn 80, in four decades, Mary joked.

The "Saddle Ridge Hoard," named for the space on their property, may be the most valuable cache ever found in North America, with an estimated value of more than $10 million. If you melted the coins, the gold alone would be worth $2 million, said David Hall, co-founder of Professional Coin Grading Services in Newport Beach, who recently authenticated them.

All dated between 1847 and 1894, 13 of the coins are the finest of their kind. One "miraculous coin," an 1866 $20 piece made in San Francisco and missing "In God We Trust," could bring $1 million on its own, Hall said. When the motto was added to the coin in 1866, some were still minted without the phrase, he said.

Had the couple attempted to clean the delicate surface of the piece, they could have reduced the value to $7,000 or $8,000 in under a minute, said David McCarthy, senior numismatist for Kagin's, who evaluated the hoard.

Buried treasure is something everyone can relate to, and the discovery has generated buzz among regular folks as well as coin collectors. The last big find was uncovered in 1985 in Jackson, Tenn. It had a face value of $4,500 and was eventually sold for around $1 million.

"It's sort of a dream I didn't even know I had coming true. It's the sort of thing, I wouldn't have the audacity to think I would ever be able to handle a deal like this," said McCarthy, who spent 31/2 months conserving one coin at a time.

Most of the hoard will be sold on Amazon.com to allow a broader swath of the public to access them, McCarthy said. The couple, who will donate some of the profit to charity, said the find will allow them to keep their property.

"A lot of people see stuff like this and all they see are dollar signs," McCarthy said. "If I got to bestow these treasures on people, I would do that on this family without even blinking an eye."

Though they attempted to track down who could have buried the treasure, the family was stymied. The area is secluded; anyone could have stashed it there, McCarthy said.

The coins are a time capsule. People in San Francisco were concerned with staying alive and feeding themselves back then, not preserving these coins for posterity, Hall said. Someone who somehow had a lot of money needed to keep it safe at a time when banks weren't always a sure thing, he said.

"It was the Wild West, so the coins weren't saved," he said. "Who knows why he did it? Maybe he did it and died before telling someone or maybe he moved or maybe he was just trying to hide money from his wife."

John and Mary said they hope to honor the history of the coins by selling them together, rather than bit-by-bit, even though it's more risky for them personally. They'll keep a small cross section of the treasure to leave for relatives when they pass on.

samantha.schaefer@latimes.com