Chiastolite cabochon with a visible natural black cross, in teardrop (36×25×6 mm) and rectangular (27×21×5 mm) formats. Mirror polish on the convex face, flat back. The cruciform pattern—organic carbon trapped in the crystal's symmetry planes—makes each piece a unique mineralogical signature.
Piece Information
| Mineral |
Chiastolite (variety of Andalusite, Al₂SiO₅) |
| Dimensions |
Teardrop: 36×25×6 mm / Rectangular: 27×21×5 mm (±0.5 mm) |
| Shape and Back |
Teardrop or rectangular, flat back |
| Finish |
Mirror polish |
| Hardness |
7–7.5 Mohs — we recommend a closed bezel setting |
| Origin |
Material acquired in the lapidary wholesale market |
| Treatment |
No treatment |
| Piece Type |
Available in 2 formats |
This Specific Piece
Chiastolite shows a black cross in cross-section due to concentrations of organic carbon—completely natural, without any intervention. No two crosses are identical in distribution or intensity. The teardrop shape is common for pendants with an asymmetrical bezel; the rectangular shape provides uniformity for coordinated sets or pairs.
How the Cross Forms
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. Cutting the cabochon perpendicularly to the main crystal axis is what reveals the pattern. Each specimen shows a unique distribution according to the temperature and pressure conditions during crystallization.
For Which Setting It Works
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Pendants with 925 silver bezel — the teardrop format works well in settings that allow the entire cross to be seen; the bezel can be simple or textured.
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Statement rings (closed bezel) — a hardness of 7–7.5 Mohs makes chiastolite suitable for frequent use with an appropriate setting.
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Wire wrap — the cross is a motif with strong symbolic meaning; it works well in character pendants.
Chiastolite in History
In Spain, it has been known since the Middle Ages as "Saint James's stone": pilgrims on the Camino carried cabochons with the natural cross as an amulet. They have been found in the burial goods of medieval pilgrims interred along the route. The name "chiastolite" derives from the Greek χιαστός ("cross-shaped"). In crystal tradition, it is associated with guidance and protection in uncertainty.
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 must be inside the mineral, not painted or inlaid. Under magnification, the edges of the arms are slightly diffuse (gradual growth), not perfect lines. With 7–7.5 Mohs, it cannot be scratched with a stainless steel knife.
Frequently Asked Questions
Is the cross natural or artificial?
Completely natural. It is the result of organic carbon distributed during crystal growth. No detectable treatment; statement based on lapidary observation.
What is the difference between the teardrop and the rectangular?
They are two separate pieces. The teardrop (36×25×6 mm) is larger and ideal as a main pendant; the rectangular (27×21×5 mm) is more compact for rings or series.
What setting is it designed for?
We recommend a closed bezel in 925 silver or copper. With 7–7.5 Mohs, it is one of the most resistant cabochons in artisanal jewelry making.
Are the dimensions exact?
Tolerance ±0.5 mm, as they are individual free-form pieces, not calibrated production.
Can it be distinguished from other grey stones?
Yes: the black cross is unequivocal. No other mineral spontaneously produces this natural cruciform pattern.
How is it cared for?
Warm water and neutral soap, dry with a soft cloth. Avoid ultrasonics. More on jewelry care.
View collection: cabochons for jewelry. See also lapidary selection.
