Material
One mineral species
Kyanite is Al₂SiO₅. A single blade, a group in quartz and grains in gneiss show different occurrences of the same mineral.
Stone Explorer → Kyanite comparison tool
Kyanite records, side by side.
Compare 5 natural kyanite specimens: a zoned blade, a group in quartz and grains in gneiss. Follow one path through metamorphic rock.
Kyanite file · 5 natural specimen records
Two ways in · pick one
Each specimen opens its own file.
Evidence
What the image can show.
Use the images to compare stones. Check the record for identity and treatment.
Appearance
Blades and blue zones
Compare the long flat shapes, colour bands and surrounding minerals. Hardness and chemical composition require testing.
Records
Locality and treatment
The photograph records name Brazilian localities. Treatment and growth ages are unrecorded for these specimens.
Sources
Sources + specimen credits
Mineral properties, geological context and photograph records.
One species, several occurrencesMaterial and evidence
Kyanite, andalusite and sillimanite share Al₂SiO₅ and have different structures. The 5 photographs show kyanite specimen records. Blue, green or orange colour labels do not create extra mineral species.
Handbook of Mineralogy · Kyanite · USGS · Al₂SiO₅ phase equilibria
Hardness has a directionMaterial and evidence
Kyanite measures about 5.5 along the blade and about 7 across it on the Mohs scale. Cleavage makes it vulnerable to knocks. Keep scratch tests off finished stones.
Handbook of Mineralogy · Kyanite · GIA · How coloured stones are analysed
Blue colour and zoningMaterial and evidence
Iron is central to blue kyanite colour. Research on Coronel Murta samples also examined titanium and chromium. A blue stripe alone establishes neither treatment nor locality.
Chen, Guo & Gao (2025) · Blue kyanite · GIA · How coloured stones are analysed
Formation and the photographed specimensMaterial and evidence
The diagram follows a regional-metamorphic pathway. Large kyanite blades also occur in hydrothermal quartz pockets at Barra do Salinas. Each photograph retains its own catalogue locality; the drawing gives no age or pressure for those specimens.
Handbook of Mineralogy · Kyanite · Chaves et al. (2025) · Barra do Salinas
Treatment and identityMaterial and evidence
Treatment status belongs to the individual specimen record. The 5 photograph entries give no treatment information. Gemmological identification combines observations and tests suited to the material.
Zoned blade on quartzCC BY-SA 3.0
Rob Lavinsky, iRocks.com, via Wikimedia Commons · CC BY-SA 3.0
Resized and compressed; colour unchanged. Cards crop the frame; the specimen file shows the full photograph. Image adaptations retain the source licence.
Blades in quartzCC BY-SA 3.0
Rob Lavinsky, iRocks.com, via Wikimedia Commons · CC BY-SA 3.0
Resized and compressed; colour unchanged. Cards crop the frame; the specimen file shows the full photograph. Image adaptations retain the source licence.
Kyanite in gneissCC BY-SA 2.0 BR
Eurico Zimbres, via Wikimedia Commons · CC BY-SA 2.0 BR
Resized and compressed; colour unchanged. Cards crop the frame; the specimen file shows the full photograph. Image adaptations retain the source licence.
Formation drawingRegional metamorphism
A conceptual cutaway through aluminium-rich metamorphic rock. Blades are enlarged for clarity. The section represents no particular deposit.
Blue, green, orange and blackMaterial reference
Kyanite occurs in blue, green, orange and black, as well as white, grey and less usual yellow or pink. A GIA study confirmed yellowish-green Tanzanian kyanite by Raman spectroscopy and related its colour to iron. The orange and black photographs add a colour reference and a radiating aggregate to the blue records; the green material is described by the linked laboratory study.
Open sourceBlades, cleavage and directionMaterial reference
Kyanite forms single blades, radiating aggregates and crystals within rock. Scratch resistance varies by direction, about Mohs 5.5 along and 7 across the crystal in the reference values used here. Cleavage remains a separate breakage risk. Avoid scratch tests on finished pieces.
Open sourceRock setting and related namesMaterial reference
Kyanite commonly occurs in metamorphic rocks; particular hydrothermal occurrences need locality-specific evidence. Andalusite and sillimanite share its formula but have different crystal structures. Quartz containing kyanite is a quartz host with inclusions. Sapphire is corundum. None of these names is a colour variety of kyanite.
Open source
