Danburite is a calcium borosilicate mineral typically found as transparent to translucent prismatic crystals that often resemble topaz or quartz. Collectors prize it for its high clarity and excellent dispersion, especially in specimens from Mexico which can display distinct chisel-like terminations.
Is this danburite?
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 danburite with a known reference. Danburite sits at Mohs 7-7.25, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to greasy.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, brownish white, straw yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: disseminated, euhedral crystals, prismatic.
Often confused with
Danburite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside danburite
Minerals reported to co-occur with danburite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaB₂(SiO₄)₂
- Mohs hardness
- 7-7.25
- Density
- 2.93-3.02 g/cm³
- Streak
- White
- Luster
- Vitreous to greasy
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Disseminated, euhedral crystals, prismatic
- Cleavage
- Indistinct on {001}
- Fluorescence
- Violet blue under SW UV; blue to blue-green under LW UV
- Rarity
- Uncommon
- Uses
- Collector, Gemstone
- Host rock
- In granite and metamorphosed carbonate rocks associated with hydrothermal activity; in evaporites
Where rockhounds find danburite
Classic worldwide localities
- Danbury, Fairfield Co., Connecticut, USA
- Russell, St. Lawrence Co., New York, USA
- Alto Chapare, Cochabamba, Bolivia
- Piz Valatscha, Mt. Scopi, south of Disentis, Graubünden, Switzerland
- Anjanabonoina, Madagascar
- Maharitra, Mt. Bity, Madagascar
Field-hunting tip
Where it forms: In granite and metamorphosed carbonate rocks associated with hydrothermal activity; in evaporites. If you start seeing titanite, axinite, tourmaline in float, you are in the right ground. Typical habit: disseminated, euhedral crystals, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
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Find danburite on the map
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