Kornerupine is a rare borosilicate mineral that forms elongated, prismatic crystals in high-grade metamorphic rocks. Collectors prize it for its unique color range, especially the rare blue-green hues, and its strong pleochroism which can shift from yellow-brown to green.
Is this kornerupine?
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 kornerupine with a known reference. Kornerupine 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. Kornerupine leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kornerupine typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellowish-green, brown, blue, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, fibrous, massive.
Often confused with
Kornerupine vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside kornerupine
Minerals reported to co-occur with kornerupine. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Fe²⁺)₄(Al,Fe³⁺)₆(SiO₄,BO₄)₅(OH,O)₂
- Mohs hardness
- 6.5-7
- Density
- 3.27-3.48 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Fibrous, Massive
- Cleavage
- Distinct in One Direction
- Rarity
- Rare
- Uses
- Gemstone, Collector
- Host rock
- Metamorphic Rocks Rich in Aluminum and Magnesium, Such as Granulites
- Typical price
- $50-500 per carat for gem quality, $20-150 for specimens
Where rockhounds find kornerupine
Classic worldwide localities
- Sri Lanka
- Madagascar
- Tanzania
- Canada
- Myanmar
Field-hunting tip
Look in metamorphic rocks rich in aluminum and magnesium, such as granulites country — that is the host setting where kornerupine typically forms. If you start seeing sapphire, spinel, garnet in float, you are in the right ground. Field specimens usually show a prismatic crystals, fibrous, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kornerupine?+
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How much is kornerupine worth?+
What rocks look like kornerupine?+
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Find kornerupine on the map
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