Benitoite is a rare and highly prized collector's gemstone famous for its intense blue color and strong blue fluorescence under short-wave UV light. It typically occurs as sharp, triangular dipyramidal crystals embedded in white natrolite veins within serpentinite. It is the official state gem of California, and the Dallas Gem Mine remains its only significant commercial locality.
Is this benitoite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch benitoite with a known reference. Benitoite sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Benitoite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Benitoite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, colorless, white, pink.
- 5Look at form & habitCrystal system: trigonal. Typical habit: triangular dipyramidal crystals.
Often confused with
Benitoite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Sapphire is the harder of the two (Mohs 9 vs. 6-6.5); streak differs — Benitoite leaves white, Sapphire leaves none.
How to tell apart: Spinel is the harder of the two (Mohs 8 vs. 6-6.5).
Often found alongside benitoite
Minerals reported to co-occur with benitoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaTiSi₃O₉
- Mohs hardness
- 6-6.5
- Density
- 3.6-3.7 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Triangular Dipyramidal Crystals
- Cleavage
- Poor On {1011}
- Fluorescence
- Bright Blue Under SW UV
- Rarity
- Rare
- Uses
- Gemstone, Collector
- Host rock
- Serpentinite
- Typical price
- $500-2000 per carat for gem quality
Where rockhounds find benitoite
Classic worldwide localities
- San Benito County, California, USA
Field-hunting tip
Look in serpentinite country — that is the host setting where benitoite typically forms. If you start seeing neptunite, natrolite, serpentine in float, you are in the right ground. Field specimens usually show a triangular dipyramidal crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find benitoite on the map
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