Oval chiastolite cabochon with visible black cross in cross-section, 33×25×7 mm. Mirror polish on convex face, flat back. The intersection of organic carbon along the symmetry axes makes this piece a unique and unrepeatable mineralogical signature.
Piece Information
| Mineral |
Chiastolite (andalusite variety, Al₂SiO₅) |
| Dimensions |
33 × 25 × 7 mm (±0.5 mm) |
| Shape and Back |
Oval freeform, flat back |
| Finish |
Mirror polish |
| Hardness |
7–7.5 Mohs — we recommend closed bezel setting |
| Origin |
Material acquired from wholesale lapidary market |
| Treatment |
Untreated |
| Piece Type |
Unique oval piece |
This Specific Piece
The 33×25 mm size falls within what jewelers call "statement ring" range: wide enough for the cross to occupy the visual field of the setting. With a 7 mm dome, the bezel grips loosely without the need for a counter-bezel, and there is enough material for wire-wrap weaving around the side.
How the Cross is Formed
Chiastolite is a variety of andalusite (Al₂SiO₅) that grows in metamorphic rocks under moderate pressure. The crystal lattice expels organic carbon towards the {110} symmetry planes, where it precipitates, forming the cross. The distribution —perfect, asymmetrical, or with arms of different thickness— is unique in each specimen according to the exact crystallization conditions.
What Setting It Works For
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Statement rings with 925 silver bezel — 33×25 mm is a classic full-stone ring size; with 7–7.5 Mohs, it withstands daily wear with an appropriate setting.
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Pendants with open bezel — the oval shape allows for a continuous bezel that shows the cross in its full development.
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Wire wrap — the 7 mm dome offers good lateral grip for securing spirals.
Chiastolite in History
Chiastolite from the Salamanca deposits was the medieval "stone of Santiago": pilgrims on the Camino carried it for protection. Scientifically described in the 19th century from these same Iberian specimens, its name derives from the Greek χιαστός ("X-shaped"). In crystal tradition, it is associated with guidance and resilience on journeys.
The symbolic properties attributed to minerals belong to cultural and historical traditions. They are shared for educational purposes, not as medical advice.
How to Recognize Genuine Chiastolite
The cross is inside the mineral: under magnification, the edges of the arms are slightly diffuse (gradual growth), not perfect engraved or pigmented lines. With 7–7.5 Mohs, it is difficult to scratch with a stainless steel knife.
Frequently Asked Questions
Is the cross natural or painted?
Natural. Organic carbon distributed during crystal growth, without any subsequent intervention. No detectable treatment; statement based on lapidary observation.
What setting is it intended for?
We recommend a closed bezel in 925 silver. With 7–7.5 Mohs, it is one of the hardest cabochons in artisanal jewelry making, which facilitates bezel finishing without risk of scratching the face.
Are the dimensions exact?
33×25×7 mm with ±0.5 mm tolerance. Freeform piece, not industrially calibrated production.
Is it suitable for daily wear rings?
With a well-executed closed bezel in 925 silver, yes. The 7–7.5 Mohs hardness makes it resistant to daily scratching.
What is andalusite and how is it related to chiastolite?
Chiastolite is a variety of andalusite with carbon inclusions. Andalusite is a polymorph of aluminum silicate (Al₂SiO₅), along with kyanite and sillimanite, differing in their formation conditions.
How to care for it?
Lukewarm water and neutral soap, dry with a soft cloth. Avoid ultrasonics. More at jewelry care.
View collection: cabochons for jewelry. See also lapidary selection.
