Benitoite is a rare blue silicate mineral, found in hydro thermally altered serpentinite. Hydro thermally altered serpentinite is science speak for a type of rock that formed by cold submarine volcanoes that rose from the ocean floor. This layer of rock is full of faults and is weak and easily eroded. When mineral laden water fill the cavities the minerals dissolved in the water sometimes crystallizes and is left behind when the water leaves.

Benitoite was named after the county where it was first found, San Benito County, in 1907 and to this day San Benito County is the only place in the world that you can find this gemstone, making it among the rarest gems on the planet. Benitoite became California's official state gemstone in 1985. The price of this gemstone is between $500 and $3,000 per carat depending the quality of the stone and most of the gems found are less than one carat in size.

This crystal is often confused with a sapphire and if the jeweler that is cutting your stone does not know the difference, he can damage the stone with the heat from their torch. The gemstone will turn orange or in the worst case break. Always use a jeweler that is familiar with this type of gemstone.

Another unique characteristic of this rare gemstone is its has a very unusual crystalline shape called ditrigonal-dipyramidal (pyramidal). It is the only known crystal to take this shape naturally. Benitoite fluoresces very strongly under short wave ultraviolet light (UV), appearing light blue in color. Treasure hunters search at night for this glowing gem with UV lights but beware, scorpions also glow at night under UV lights and some hunters have been stung by them.

Benitoite have a very high dispersion which makes them very bright. They have a refractive index of 1.757 to 1.804. This characteristic makes sparkle brighter than diamonds. They have a hardness rating of about 6.5 on the Mohs scale which is not nearly as hard as a diamonds that has a rating of 10.

The Benitoite Gem Mine has field trips open to the public. You will need to make reservation in advance and in the winter or rainy season, because of the bad roads; you will need to reconfirm your reservations 1 or 2 days prior to your trip. No services other than a porta-potty are on site and the nearest food and water is at least three hours away.

The mine opens at 8:00 AM and closes at 4:00 PM. For about $100 per day per person you are allowed to take home a five-gallon bucket of material. Night field trips are also available where you can hunt for benitoite with black lights. A mine guide there to help and explain what to look for, how to operate the screens, how to night hunt using a black light and other information.

The roads to Benitoite Gem Mine area are very rough and suitable for 2WD vehicle with a high clearance during the dry season. A 4WD is always the preferred automobile and never try to make the trip in the family sedan. Campsites are available on the surrounding BLM land except in the summer months when camping is prohibited on BLM land. If possible drive in one day and camp overnight and then take the full day treasure hunting.

Happy Treasure Hunting.