Sinhalite is a rare magnesium aluminum borate mineral that was historically mistaken for olivine or chrysoberyl due to its similar appearance. It typically occurs as transparent, brownish-yellow crystals and is primarily sought after by gem collectors for its high refractive index and distinct physical properties.
Is this sinhalite?
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 sinhalite with a known reference. Sinhalite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow, brown, brown pink, colorless, light pink.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, rounded grains.
Often confused with
Sinhalite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside sinhalite
Minerals reported to co-occur with sinhalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgAlBO₄
- Mohs hardness
- 6.5-7
- Density
- 3.47-3.50 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic crystals, rounded grains
- Cleavage
- Distinct in one direction
- Rarity
- Rare
- Uses
- Gemstone, Collector
- Host rock
- A rare accessory mineral formed in boron-rich skarns at the contact of limestones with granite or gneiss
Where rockhounds find sinhalite
Classic worldwide localities
- Johnsburg, Warren Co., New York, and in the Bodnar quarry, near Hamburg, Sussex Co., New Jersey, USA
- Gem gravels, in the Ratnapura district, at Nivitigala, Balangoda, Nirialla, Sri Lanka
- Elahera and Eheliyagoda, Sri Lanka
- Mogok, Myanmar, in gem gravels
- Found near Bancroft, Ontario, Canada
- Kwakonje area, Handeni district, Tanzania
Field-hunting tip
Where it forms: A rare accessory mineral formed in boron-rich skarns at the contact of limestones with granite or gneiss. If you start seeing spinel, serendibite, ludwigite in float, you are in the right ground. Typical habit: prismatic crystals, rounded grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sinhalite?+
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What rocks look like sinhalite?+
What minerals are found with sinhalite?+
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Find sinhalite on the map
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