Gemstones entice with their brilliance, various hues, and light reflecting off their sparkling facets. Walk past any jewelry store window and you’ll most likely see baubles made with diamonds, rubies, sapphires, emeralds and amethysts. These common gems are valued for their color and clarity, but not for their rarity, which is determined by accessibility, availability and abundance. There are few extremely rare gems in the world—and one of them, bentonite, comes from San Benito County.
The story of benitoite captures the spirit of the 49er gold-seekers who first coined our state motto, Eureka (Ancient Greek for “I have found it.”) As so often happens in prospecting, benitoite was discovered while looking for something else—in this case, it was cinnabar, an ore found in mercury, and not gold.
It was 1907, and Coalinga resident James Couch was prospecting for cinnabar in a remote section of the Diablo Range. He set up camp near the headwaters of the San Benito River, at the southern end of the county, in the New Idria mining district, where the New Idria Mercury Mine was then operating. Couch climbed a hill near his camp when he stumbled across an area covered in snow white silica embedded with small, dark blue crystals. He thought they were sapphires and collected as many as he could carry before heading back to Coalinga to announce his discovery.
The Couch samples were sent off to Dr. George Louderback at the University of California, Berkeley for analysis. Louderback confirmed that the blue crystals were indeed a new mineral and named it after the area in which it was found. Benitoite is one of the top 12 rarest and most expensive—at $4,000 per carat—gemstones in the world, according to a 2015 article in Forbes magazine.
“In the world of crystals, benitoite is unique,” says John Veevaert, a geologist in Reno, Nevada, who currently owns the largest personal collection in the world of this rare blue mineral. Today we know the same area where Couch was prospecting as Benitoite Gem Mine, which was referred to up until the 1960s as the Dallas Gem Mine, named after its financial backer R.W. Dallas.
But the discovery provided mineralogists with more than just a new mineral: “There are six basic shapes [of crystal formations]—cubic, tetragonal, orthorhombic, hexagonal, triclinic and monoclinic,” Veevaert explains. “Early in the theoretical development of crystallography, it was hypothesized that there was a class of the hexagonal system that would produce trigonally [triangular] shaped crystals. The discovery of benitoite proved this hypothesis.”
Crystals in this triangular shaped class are now referred to as Benitoite Type.
Benitoite is stunning in both its natural and polished state. It’s polychroic, or multicolored, and the most common color is a deep sapphire or indigo blue with hints of violet. It’s also found in clear, white, pink and greenish-gray. Considered a double refracting crystal, benitoite comes alive when light hits it, radiating a whole rainbow of colors.
The California Federation of Mineralogical Societies proposed in 1984 that it be adopted as the state’s gemstone, and in 1985, it was made official.
At only 6.5 on the Mohs scale of mineral hardness—a one through 10 scale that places Talc at one and diamonds at 10—benitoite isn’t the strongest of stones.
“As a gemstone, benitoite is not well-suited for rings, due to its softness,” says Veevaert. “But it’s spectacular in pendants and bracelets. The vast majority of finished gems are under 0.5 carat in weight. Gems over 1 carat are rare, and gems over 2 carats are considered very rare. If you took all of the [2 carat] gems in the world, it might fill a 3x3x3 [foot] box.”
While benitoite is found in other parts of California and the country, as well as in Japan and Australia, none of it matches the quality or quantity once found in San Benito County.
Benitoite Prospects
Although rare to find any large specimens, TOPS A Rock Shop in San Juan Bautista, sells benitoite they’ve been purchasing from vendors for the last 30 years.
“The types of specimens that we have here are rough pieces that have been worked. It’s a long process. You have to dip it out of acids to expose the rock,” says Kammie Osborn, owner of TOPS, whose benitoite specimens range from $4 to $1500, with faceted pieces, or an actual gemstone that has been cut, ranging from $50 to $4000.
“The mine is not so much empty,” says Osborn of the Benitoite Gem Mine. “They still do day trips up there.”
John Shriner co-owner at California State Gem Mine, who purchased the mine in 2005, says they are not currently offering tours up to the actual mine itself, but it’s open on weekends via reservation for a fee dig at $70 per person, less for seniors and children under 12.
In 2004, the Bureau of Land Management and the Environmental Protection Agency closed the area around the New Idria Mercury Mine to all vehicular traffic because of the presence of naturally occurring asbestos, erosion problems caused by all-terrain and motorcycle operators, and to protect natural plant species, says Veevaert. “I was fortunate to have been able to visit the [benitoite] mine prior to its closure and personally collect specimens,” says Veevaert.
In 2008, Veevaert purchased the 9-plus ton of inventory that was still on-site and made it available to collectors.
Considering that much of the larger stones have been mined prior to the initial 2004 closure, Shriner says that, at an average of .5 carat to 1 carat, weight of the stones available at the fee digs don’t disappoint.
“I would say one out of every two people walk away with a .5 carat,” says Shriner. “Benitoite is a very small gemstone, I always equate it to diamonds.”
Mystical Enthusiasts
More than a pricey stone, benitoite is believed by some to have special healing properties. Sela Weidemann, author of Rock Medicine: Earth’s Healing Stones from A to Z: A Guide to the Practical Use of Rocks, Crystals & Gemstones also worked at TOPS Rock Shop in the 1990s. Weidemann, who says she’s the medicine woman for the Kiowa tribe, takes a different approach than most healers.
“I was impressed with the knowledge that benitoite is for greed,” says Weidemann. “We have three bodies; physical, mental and spiritual, and we have stones that treat each of these areas.”
Wiedemann posits the chemical properties of stones correspond to the same chemicals in the body. In the case of benitoite, which has a chemical composition of barium, titanium, and silicate and corresponds to the brain’s cerebellum—which, according to Weidemann “is the portion of our entire body that holds the highest quantity of nitric oxide. And barium is the chemical that triggers the balance nitric oxide,” she says.
“Benitoite, because of it’s barium content balances the cerebellum because that’s where greed comes from,” says Weidemann.
No matter what attracts you to benitoite—it’s mystical allure, beauty, rarity, or the thrill of hunting for it—there is no question that it’s a sight to behold.
“When I dream at night, I dream about blue triangles,” Veevaert says, and it’s not hard to believe. “The magnificent crystals of this new gem caused quite a sensation in the world of mineralogy.”
By Susan Hart and Debra Eskinazi
