Overview

Kyanite is an aluminum silicate polymorph (Al2SiO5) best known for its striking sapphire-blue blades and strong pleochroism. It forms alongside its polymorphs andalusite and sillimanite in medium- to high-grade metamorphic rocks, typically schists and gneisses. Collectors prize kyanite for its color, texture, and dramatic bladed crystals—ranging from glassy, gemmy prisms to broad, lustrous “book-like” blades. Most specimens show deep royal to cornflower blue, but green, teal, gray, black, and even orange crystals occur from select localities. Kyanite is unusual in having direction-dependent hardness: approximately 4.5–5 parallel to the length of the blades and 6.5–7 across the blade, making it both fascinating and somewhat delicate. Classic displays show bold blue fans rising from silvery muscovite schist or contrasting against white quartz, with occasional associations such as garnet (almandine), staurolite, rutile, and lazulite adding visual interest.

Popularity

Kyanite has long been an educational staple for demonstrating polymorphism and anisotropic hardness, but in recent decades it has also earned respect as an aesthetic species. Major gemmy finds from Nepal brought superb transparent crystals to the market, elevating kyanite from a “teaching sample” to a cabinet-worthy showpiece. Equally, historic sites like Graves Mountain (Georgia, USA) gave generations of collectors bold, deep-blue blades intergrown with rutile and lazulite—signature pieces of American mineralogy. Tanzanian pockets from Merelani—more famous for tanzanite—have yielded elegant, sharply terminated kyanites, while Brazil and Madagascar continue to provide attractive matrix pieces and large, sculptural clusters. Prices vary widely: common rough blades are affordable, but large, clean, lustrous crystals with fine color—especially on pretty matrix—command strong premiums. As a species, kyanite offers both accessibility and the thrill of the exceptional.

Top Collecting Localities

While kyanite is widespread, a handful of regions are renowned for producing high-quality or distinctive specimens. Below are notable sources with a track record of producing collector-grade material.

Collector’s Guide

Evaluating Specimen Quality

• Color and Pleochroism: Deep, even royal to cornflower blue is most sought after, though teal and greenish-blue can be desirable. Rotate the crystal and view in different lights; strong pleochroism can pleasantly shift intensity from pale to saturated. Avoid muddy or gray tones unless compensated by exceptional size or composition.

• Clarity and Luster: Gemmy tips and translucent zones greatly enhance appeal, especially in Nepalese crystals. On more opaque blades (e.g., Graves Mountain), favor bright luster and clean surfaces. Natural striations are normal; the best faces look glassy and reflective rather than dull.

• Crystal Form and Terminations: Sharp, complete terminations significantly increase value. Look for symmetric, well-developed prisms or elegant blade clusters. Fans and sprays can be highly aesthetic. On matrix, evaluate how the crystal sits—contrasting white quartz or silvery muscovite often elevates the piece.

• Size and Proportions: Kyanite can reach impressive lengths. Large, thick blades with good color are desirable, but thin, straight, undamaged prisms can be equally fine, especially when gemmy. Ideally, the main crystal dominates but doesn’t overwhelm the composition.

• Condition: Kyanite has perfect cleavage; edges and tips are easily nicked. Inspect terminations and blade margins under good light for chips. Preference goes to undamaged tips; small backside contacts are acceptable. Because hardness is directional, even minor knocks can create clean cleavage lines—choose the crispest piece you can.

• Associations and Matrix: Staurolite, almandine garnet, rutile, quartz, and lazulite are classic pairings and often boost desirability. Matrix that supports the blade and frames it (rather than burying it) is ideal. In multi-species pieces (e.g., Graves Mountain), balance and contrast are key.

Detecting Repairs or Treatments

• Repairs: Reattached blades or terminations are not uncommon. Check for perfectly straight seams, slight misalignment along striations, or glossy glue lines under magnification. Some epoxies fluoresce under longwave UV. Repaired specimens can be acceptable if disclosed and well executed, but unrepaired pieces carry a premium.

• Polishing: Occasionally, broken ends are lightly polished to mimic terminations. Polished surfaces may look too mirror-like and lack subtle growth features. Compare the luster and micro-texture of the “termination” to natural prism faces.

• Treatments: Kyanite is seldom treated as a specimen. Dyeing is rare but possible in low-grade material; look for color concentrations in cracks or uneven saturation. Heat treatment is generally avoided—excessive heat risks structural change—so it’s not a typical concern for natural specimens.

Care and Storage

Kyanite’s perfect cleavage and directional hardness demand gentle handling despite its relatively high cross-blade hardness.

• Handling: Support specimens from the base or matrix, not by the tips. Avoid pressure along the blade’s length. For transport, wrap in soft tissue or foam with rigid outer support so blades can’t flex.

• Display: Keep out of accidental traffic zones. A small dot of museum putty can secure bases to shelves. Avoid strong vibrations that could propagate cleavage.

• Light and Temperature: Normal display lighting is fine; color is generally stable. Avoid high heat or sudden temperature swings that could induce stress cracks or affect associated minerals.

• Cleaning: Use soft brushing or compressed air for dust. If needed, wash gently with lukewarm water and a drop of mild soap; rinse and air-dry thoroughly. Avoid ultrasonic or steam cleaners—vibration and heat can cause cleavage. Be cautious with acids and chemical rust removers; while kyanite is relatively resistant, matrix minerals (mica, calcite) may not be.

• Storage: Provide individual padding in drawers or boxes. Don’t let heavier/harder specimens rest against kyanite blades. Monitor repaired specimens after cleaning to ensure adhesives haven’t been compromised. Label provenance—locality adds significant value, especially for Nepal, Graves Mountain, or Merelani material.

By focusing on color, luster, sharp terminations, and careful handling, collectors can acquire kyanite specimens that are both scientifically intriguing and aesthetically striking—true blue standouts in any cabinet.