California's rare benitoite: The only place on Earth to dig for this glowing gem

California's rare benitoite: The only place on Earth to dig for this glowing gem | Bartell's Backroads

In 1907, as oil was being pulled from the sandy soils of Coalinga, California, a prospector named James Marshal Couch made a discovery that would sparkle through history. While exploring the rugged San Benito Mountains, Couch stumbled upon a strange outcrop littered with tiny blue crystals.

“When they originally found it, they thought it was sapphire,” said John Schreiner, who now operates the Benitoite Mining Company with his father. “Later that year, they gave it to a professor at Berkeley — Doctor George Lauterbach — and he discovered it was a brand new species that had never been discovered before.”

That new species would later be named Benitoite, now one of the rarest gemstones on Earth and only found in one location: the very spot where Couch first unearthed it.

“This is the only place you can find it is right here,” Schreiner said. “You can only find Benitoite right here. That’s it.”

Today, the Benitoite Mining Company is a family-run operation owned by Schreiner and his father Dave, who purchased the historic mine in 2005 after a series of commercial ventures failed due to supply issues.

“Tiffany’s actually wanted to make an exclusive deal with them,” John Schreiner said, referencing a previous owner. “But I imagine Benitoite is so rare that they probably couldn’t mine enough for Tiffany’s bottom dollar.”

Rather than extracting and selling the gemstones commercially, the Schreiners decided to take a different route in opening the mine to the public and turning the experience into a hands-on dig, similar to a “you-pick” orchard.

“What we’re doing is we’re building lifelong memories for the kids that come here,” Dave Schreiner said. “They remember this the rest of their lives.”

Visitors receive all the tools they need: shovels, sifting boxes and water trays to help separate gems from gravel. Though the process is labor-intensive and often dirty, the payoff can be extraordinary.

“It’s a very dirty job,” said Schreiner, as guests sifted through gravel and rocks. “You can throw the big rocks out. I know nothing will be in those.”

What makes Benitoite particularly special is its glow. Under UV black lights, the blue crystals illuminate with a ghostly brilliance.

In 1985, Benitoite was named the official state gemstone of California. And while many visitors leave with a specimen, not every find is valuable. A flawless one-carat Benitoite gemstone can command between $8,000 and $10,000, nearly double the value of a similar-sized diamond.

“It has to be flawless,” Schreiner said.

If you’re lucky, you could strike big. In 2007, a 34.7-carat Benitoite crystal was unearthed at the mine. It was later cut into four gemstones worth thousands of dollars.

But for Dave Schreiner, it’s not about the money.

You may not retire on a Benitoite discovery, but you will take home a rare memory only found in the wild and rocky hills of California’s San Benito Mountains.

MORE GEMS FROM THE BACKROADS: This Northern California rock, gem, and mineral shop is just a stone's throw from Highway 101 and the Pacific coast.