The facts
What chiastolite actually is
The species behind chiastolite is andalusite, Al₂SiO₅ with carbonaceous inclusions; it forms in the orthorhombic system.
Grey-brown host with a black cross formed by carbonaceous material concentrated along the crystal's growth edges is responsible for the colour — and the chromophore, not the name, is what decides whether a colour is stable.
On the instruments it reads a refractive index of 1.629–1.650 (spot ~1.64) and a specific gravity of about 3.10–3.20, with distinct {110} cleavage.
Where chiastolite comes from
Commercial material comes from Lancaster and Sterling, Worcester County, Massachusetts, USA, Bimbowrie, South Australia, Galicia, Spain and Hunan, China.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How chiastolite is treated
Untreated; the cross is a natural growth pattern seen in cross-sections. Historically worn as amulets in Spain and Brittany. Carved and painted imitations exist.
We state the treatment on every stone, including when the honest answer is that it cannot be determined. A treatment disclosed is a fact; a treatment discovered later is a refund.
What chiastolite is confused with
Watch for Carved imitations, Staurolite 'fairy crosses', Andalusite and Painted stone — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.629–1.650 (spot ~1.64) and specific gravity 3.10–3.20 settle most of it in a minute, and magnification settles the rest.
What chiastolite is used for
The trades that buy chiastolite are mineral collecting, decorative objects, jewellery and wellness and body care. They do not want the same thing, and they do not pay in the same unit.
We quote each application in the unit that trade actually buys in, by the specimen, by the piece or by the carat.
Durability and care
Hardness 7–7.5; cleavage distinct {110}. That combination decides what it can safely be set into.
With no cleavage plane to worry about, the practical limit is abrasion rather than breakage, and it takes daily wear well.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What chiastolite costs
Expect roughly $1–20/ct, depending on quality.
That is a range, not a quote. Colour, size, clarity, cut and origin move the figure a long way inside it, and the only honest price is one given against a specific stone. Send us what you need and we will price it.
Questions
Is chiastolite treated, and how?
Untreated; the cross is a natural growth pattern seen in cross-sections. Historically worn as amulets in Spain and Brittany. Carved and painted imitations exist.
Where does chiastolite come from?
Lancaster and Sterling, Worcester County, Massachusetts, USA, Bimbowrie, South Australia, Galicia, Spain and Hunan, China. Origin affects price, so we name the locality rather than the country on every quote.
Is chiastolite hard enough to wear every day?
Yes. At 7–7.5 on the Mohs scale with no cleavage plane, it handles daily wear well. The practical limit is gradual abrasion rather than chipping.
How much does chiastolite cost?
Indicatively $1–20/ct. Colour, size, clarity and origin move the price a long way within that, so treat it as a range and ask for a quote against a specific stone.
What is chiastolite confused with?
Most often Carved imitations, Staurolite 'fairy crosses', Andalusite and Painted stone. A refractive index of 1.629–1.650 (spot ~1.64) and a specific gravity near 3.10–3.20 separate it quickly.
What is chiastolite used for besides jewellery?
mineral collecting, decorative objects and wellness and body care. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for chiastolite?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
Ask about chiastolite