The facts
What crinoidal Limestone actually is
The species behind crinoidal Limestone is limestone composed largely of crinoid ossicles, which polish to a distinctive spangled pattern, Calcite CaCO3, each crinoid ossicle a single calcite crystal; it forms in the aggregate (each ossicle a trigonal calcite single crystal) system.
Organic carbon darkens the matrix; the pale ossicles give the contrast, and each one flashes as a cleavage face catches the light 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 1.486-1.658 and a specific gravity of about 2.60-2.75, with rhombohedral cleavage through whole ossicles - visibly, which is the diagnostic cleavage.
Where crinoidal Limestone comes from
Commercial material comes from Ashford-in-the-Water and Derbyshire Peak District, England (Ashford Black Marble and grey fossil marble), Kilkenny, Ireland (Kilkenny black marble), Belgium (petit granit, Tournai) and Missouri and Iowa, USA (Burlington Limestone).
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How crinoidal Limestone is treated
Polished and waxed; Ashford Black Marble was historically inlaid with coloured stone as Derbyshire pietra dura. Acid-sensitive. Quarrying at the classic English sites has largely ceased, so architectural restoration relies on salvaged stock. Not CITES.
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 crinoidal Limestone is confused with
Watch for Ordinary dark limestone, Belgian bluestone and Black marble — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.486-1.658 and specific gravity 2.60-2.75 settle most of it in a minute, and magnification settles the rest.
What crinoidal Limestone is used for
The trades that buy crinoidal Limestone are architecture and interiors, carving and sculpture, decorative objects and mineral collecting. 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 square metre, by the block or by the piece.
Durability and care
Crinoidal Limestone is 3-4 on the Mohs scale, with rhombohedral cleavage through whole ossicles - visibly, which is the diagnostic cleavage.
Below about 5.5 a stone will be scratched by ordinary household dust, which is largely quartz. That does not make it unusable — it makes it a pendant, an earring or an object rather than a ring worn every day.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What crinoidal Limestone costs
Expect roughly $20-80 per square foot as dimension stone; antique Ashford inlay work prices as antiques, 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 crinoidal Limestone treated, and how?
Polished and waxed; Ashford Black Marble was historically inlaid with coloured stone as Derbyshire pietra dura. Acid-sensitive. Quarrying at the classic English sites has largely ceased, so architectural restoration relies on salvaged stock. Not CITES.
Where does crinoidal Limestone come from?
Ashford-in-the-Water and Derbyshire Peak District, England (Ashford Black Marble and grey fossil marble), Kilkenny, Ireland (Kilkenny black marble), Belgium (petit granit, Tournai) and Missouri and Iowa, USA (Burlington Limestone). Origin affects price, so we name the locality rather than the country on every quote.
Is crinoidal Limestone hard enough to wear every day?
Not really. At 3-4 on the Mohs scale it is softer than the quartz dust in ordinary household dirt, so it scratches with wear. It suits pendants, earrings and objects better than a daily ring.
How much does crinoidal Limestone cost?
Indicatively $20-80 per square foot as dimension stone; antique Ashford inlay work prices as antiques. 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 crinoidal Limestone confused with?
Most often Ordinary dark limestone, Belgian bluestone and Black marble. A refractive index of 1.486-1.658 and a specific gravity near 2.60-2.75 separate it quickly.
What is crinoidal Limestone used for besides jewellery?
architecture and interiors, carving and sculpture, decorative objects and mineral collecting. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for crinoidal limestone?
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 crinoidal limestone