Quick Facts
Formation & Origin
Kornerupine is a rare magnesium-aluminum borosilicate mineral that occasionally yields faceted gems in green, brown, and blue-green hues. Kornerupine forms during high-grade metamorphism of boron-bearing, magnesian sedimentary rocks. The combination of magnesium, aluminum, boron, and silicon under high temperatures and pressures is relatively unusual, making kornerupine a rare mineral.
Gem-quality kornerupine is found primarily in alluvial deposits in Sri Lanka and Madagascar, where weathering has freed crystals from their metamorphic host rocks. The green color comes from iron and vanadium, while brown tones are produced by different iron valence states.
Kornerupine was named in 1884 after Andreas Nikolaus Kornerup, a Danish geologist and artist who explored Greenland. Despite its attractive colors and good hardness for jewelry use, it remains virtually unknown outside serious gem collector circles due to its rarity.
Identification Guide
Kornerupine shows strong pleochroism: green, yellow-brown, and reddish-brown from different crystal directions. This strong trichroism is a key diagnostic feature. RI of 1.660-1.682 and SG of 3.28-3.35 help separate it from similar-looking gems.
Distinguish from tourmaline (trigonal vs orthorhombic, different RI), enstatite (different pleochroism), and green sapphire (higher RI, trigonal). Cat's-eye kornerupine from Madagascar is distinctive and quite attractive.
Spotting Fakes
Kornerupine is too rare and obscure to be commonly faked. The main risk is misidentification: it's sometimes confused with green tourmaline or enstatite. Proper gemological testing (RI, SG, pleochroism) confirms identity. Any claimed kornerupine over 5 carats should be lab-verified, as large stones are exceptionally rare.
Some links in this post go to Amazon. Crystal Almanac earns a commission from qualifying purchases at no extra cost to you. Tools recommended here are ones we would use ourselves to run the tests described - the recommendation comes first, the link is downstream of it.
Cultural & Metaphysical Traditions
Presented as cultural traditions, not scientific evidence
Kornerupine is a relatively recent discovery in crystal healing circles. Practitioners associate it with teaching and sharing knowledge, perhaps influenced by its namesake's role as an explorer and educator. Its rarity is seen as connecting to themes of uniqueness and the value of being true to one's own nature rather than following trends.
Metaphysical and “healing” associations are cultural traditions, not medical advice or scientific fact. Crystals are not a substitute for professional medical care.
Where It's Found
Primary gem source, green and brown stones
Cat's-eye kornerupine and faceting grade
Fine green gem material
Notable green specimens
Type locality, named after Danish geologist Andreas Kornerup
Price Guide
Good to Know
Scratch test: At hardness 6.5, Kornerupine resists scratching from a knife but can be scratched by quartz. Best for pendants and earrings rather than rings.
Global supply: Found in 5 notable locations worldwide, from Sri Lanka to Greenland.
Heft test: Kornerupine has average mineral density (3.28-3.35). It feels about as heavy as you'd expect from a stone its size.
Care & Safety
What kornerupine can and cannot tolerate, based on its hardness (Mohs 6.5) and chemistry (Mg₃Al₆(Si,Al,B)₅O₂₁(OH)).
Can Kornerupine go in water?
Yes. Kornerupine is not water-soluble and durable enough (Mohs 6.5), so plain water is fine for rinsing and cleaning with mild soap. Avoid prolonged soaking, which serves no purpose, and dry the stone afterward.
Can Kornerupine go in salt water?
Not recommended, even though kornerupine itself is hard and not water-soluble. Salt is corrosive and mildly abrasive: it can dull a polished surface, attack metal settings, and crystallize inside small fractures as the stone dries. A brief dip will not destroy kornerupine, but rinse it with fresh water afterward and dry it. For routine cleaning, plain water is the safer choice.
Sources & References
The mineralogical and gemological data on this page is drawn from and can be cross-checked against these external references.
- WikipediaKornerupine on Wikipedia
- WebmineralKornerupine mineral data (Webmineral)
- Handbook of MineralogyKornerupine (Handbook of Mineralogy, PDF)
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