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Kyanite, Meaning, Properties, and Facts
Al2SiO5Mohs 4.5 to 7Triclinic
Kyanite is an aluminum silicate that grows in long blue blades, and it has two hardnesses depending on which way you scratch it. Below: what it is, its properties, where it is found, how to spot a fake, care, value and the meaning people give it.
What is kyanite
Kyanite is aluminum silicate, the same chemistry as andalusite and sillimanite packed into a denser structure that forms under high pressure. That makes it a clue for geologists: kyanite in a schist or gneiss means the rock was squeezed deep in the crust. The name comes from the Greek kyanos, dark blue. Most mined kyanite never reaches a shelf. It goes into refractories, the heat-proof bricks and ceramics that line kilns and furnaces, because heating turns it into mullite, which holds up at furnace temperatures.
Kyanite properties
Kyanite properties are unusual for a crystal people keep: it is heavy for its size, it splits easily along its length into thin blades, and its hardness changes with direction. Full data is on Mindat's kyanite page.
| Mineral | Kyanite |
|---|---|
| Chemistry | Al2SiO5 (aluminum silicate) |
| Color cause | Iron and titanium, the same pair that colors blue sapphire |
| Hardness | 4.5 to 5 along the length, 6.5 to 7 across |
| Crystal system | Triclinic |
| Luster | Glassy to pearly |
| Specific gravity | About 3.6 |
| Main localities | Brazil, Nepal, Switzerland, India, Virginia |
| Water safe | Yes; dry it right away |
| Sun safe | Yes |
Kyanite hardness
Kyanite hardness depends on direction: about 4.5 to 5 along the length of a blade and 6.5 to 7 across it. A steel knife will scratch a blade lengthwise and slide off it crosswise. That split personality gave kyanite its old name, disthene, from the Greek for two strengths. See where that range sits on the Mohs hardness scale.
Where kyanite is found
Kyanite is found in metamorphic rocks, mainly schist and gneiss, and in quartz veins and pegmatites that cut through them. Brazil produces many of the blue blades on the market, Nepal is known for transparent gem crystals, and the Swiss Alps gave the classic specimens of blue kyanite in white mica schist. India and the United States mine it for industry, with a major operation at Willis Mountain in Buckingham County, Virginia (Virginia Energy on kyanite).
Kyanite colors and crystal forms
Kyanite colors are mostly blue, often streaky with darker centers, and the kyanite crystal habit is a long, flat blade. Blades grow alone, in sprays and in radiating clusters, often with quartz. Green, gray, white and black kyanite exist, and Tanzania produces a rare orange kyanite colored by manganese. Black fan-shaped sprays are sold as black kyanite or witch's broom.
How to tell if kyanite is real
To tell if kyanite is real, check the shape and the hardness. Natural kyanite forms flat blades with lengthwise striations and streaky, uneven blue, and it feels heavy for its size. Dyed quartz or glass shows even color, bubbles or color pooled in cracks. The two-direction scratch test is a strong clue, but try it on a hidden spot, if at all. Check clusters for glue where broken blades were reattached.
Kyanite care: water and sun
Kyanite care is simple with water and sun: rinse it, dry it right away and display it in daylight, because water does not dissolve it and light does not fade it. The real risk is breakage. Blades split along their length, so lift a cluster by its base, never by a blade, and store it where nothing will knock it. See water safe crystals.
Kyanite price and value
Kyanite price and value depend on color, clarity and condition. Raw blades and small clusters are inexpensive. Prices rise for deep, even blue, unbroken blades, large sprays and transparent material clean enough to facet.
Kyanite meaning and benefits
Kyanite meaning in crystal lore is alignment and clear communication, and the benefits people claim for it include calm and balance. Lore also says kyanite never needs cleansing. That is belief, not chemistry. The chemistry is a good story on its own: one formula, three minerals, and a crystal that is soft one way and hard the other.
Kyanite for sale
Kyanite for sale in the first drop is one piece: a raw kyanite cluster from Brazil, one of one and photographed in daylight.
Kyanite FAQ
Is kyanite water safe?
Kyanite is water safe: it does not dissolve or soften, so a rinse is fine as long as you dry it.
Why do kyanite crystals have two hardnesses?
Kyanite crystals have two hardnesses because the bonds in their structure are stronger across the length than along it.
Can kyanite go in the sun?
Kyanite can go in the sun: its blue does not fade in normal light.
Is kyanite rare?
Kyanite is not rare: it is mined by the ton for refractories, though transparent gem crystals are scarce.
Sources
- Kyanite, Wikipedia
- Kyanite, Mindat
- Kyanite, geology.com