Serendibite is an exceptionally rare borosilicate mineral prized by collectors for its deep blue to green-blue color. It typically forms in contact metamorphic zones where boron-rich fluids interact with carbonate rocks. Due to its scarcity and refractive indices, it is one of the most expensive and sought-after gems in the mineral world.
Is this serendibite?
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 serendibite with a known reference. Serendibite sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Serendibite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Serendibite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, blue-green, black, gray.
- 5Look at form & habitCrystal system: triclinic. Typical habit: anhedral to subhedral grains or tabular crystals.
Often confused with
Serendibite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside serendibite
Minerals reported to co-occur with serendibite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Mg₃Al₄Si₃B₄O₂₀
- Mohs hardness
- 6.5-7
- Density
- 3.4-3.5 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Anhedral to Subhedral Grains or Tabular Crystals
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector, Gemstone
- Host rock
- Metamorphosed Limestone or Dolomitic Skarns
- Typical price
- $500-5000+ per carat for facet-grade material
Where rockhounds find serendibite
Classic worldwide localities
- Sri Lanka
- Myanmar
- USA
- Canada
- Tanzania
Field-hunting tip
Look in metamorphosed limestone or dolomitic skarns country — that is the host setting where serendibite typically forms. If you start seeing diopside, spinel, phlogopite in float, you are in the right ground. Field specimens usually show a anhedral to subhedral grains or tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify serendibite?+
Where is serendibite found?+
How much is serendibite worth?+
What rocks look like serendibite?+
What minerals are found with serendibite?+
What kind of rock does serendibite form in?+
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Find serendibite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
