The facts
What limestone actually is
Mineralogically, limestone is sedimentary carbonate rock, chiefly of biogenic or chemically precipitated calcite — Calcite CaCO3, with dolomite, clay, silica and organic matter, crystallising in the aggregate (trigonal calcite) system.
The colour is caused by organic carbon for grey and black, iron oxides for buff and cream, glauconite for green. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.486-1.658, and the specific gravity sits near 2.30-2.75; cleavage is rhombohedral cleavage in the calcite grains.
Where limestone comes from
The recognised sources are Isle of Portland, Dorset, England (Portland stone - St Paul's Cathedral), Salem and Bedford, Indiana, USA (Indiana limestone), Lecce, Puglia, Italy (pietra leccese), Jerusalem and Hebron, Levant (Jerusalem stone) and Solnhofen, Bavaria, Germany (lithographic limestone, and a world-class fossil Lagerstatte).
Origin affects price in this material, so we name the locality on every quote rather than the country. "African" or "Asian" tells a buyer nothing.
How limestone is treated
Sawn, honed and sealed; acid-sensitive and dissolves slowly in rain, which is the central conservation issue for historic buildings. Industrially it dwarfs its ornamental use: cement, steel flux, agricultural lime, glass, and flue-gas desulphurisation. Solnhofen limestone fossils (Archaeopteryx and others) are protected under German heritage rules. Not CITES.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What limestone is confused with
The usual confusions are Marble (recrystallised), Travertine, Dolostone and Cast stone.
The separation is rarely a matter of opinion: refractive index 1.486-1.658 and specific gravity 2.30-2.75 settle most of it in a minute, and magnification settles the rest.
What limestone is used for
Limestone is bought by architecture and interiors, heavy industry, carving and sculpture and decorative objects — and each of those trades wants a different form of the same material.
We quote each application in the unit that trade actually buys in, by the square metre, by the tonne or by the block.
Durability and care
Limestone is 3-4 on the Mohs scale, with rhombohedral cleavage in the calcite grains 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 limestone costs
Indicative pricing for limestone is $3-25 per square foot as dimension stone; crushed aggregate $10-20 per tonne.
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 limestone treated, and how?
Sawn, honed and sealed; acid-sensitive and dissolves slowly in rain, which is the central conservation issue for historic buildings. Industrially it dwarfs its ornamental use: cement, steel flux, agricultural lime, glass, and flue-gas desulphurisation. Solnhofen limestone fossils (Archaeopteryx and others) are protected under German heritage rules. Not CITES.
Where does limestone come from?
Isle of Portland, Dorset, England (Portland stone - St Paul's Cathedral), Salem and Bedford, Indiana, USA (Indiana limestone), Lecce, Puglia, Italy (pietra leccese), Jerusalem and Hebron, Levant (Jerusalem stone) and Solnhofen, Bavaria, Germany (lithographic limestone, and a world-class fossil Lagerstatte). Origin affects price, so we name the locality rather than the country on every quote.
Is 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 limestone cost?
Indicatively $3-25 per square foot as dimension stone; crushed aggregate $10-20 per tonne. 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 limestone confused with?
Most often Marble (recrystallised), Travertine, Dolostone and Cast stone. A refractive index of 1.486-1.658 and a specific gravity near 2.30-2.75 separate it quickly.
What is limestone used for besides jewellery?
architecture and interiors, heavy industry, carving and sculpture and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for 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 limestone