The facts
What calcite actually is
Mineralogically, calcite is calcite — CaCO₃, crystallising in the trigonal system.
The colour is caused by colourless when pure; Mn²⁺ (pink), Fe (yellow-brown), Co²⁺ (pink), organic matter and inclusions for other hues. 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 (birefringence 0.172), and the specific gravity sits near 2.69–2.71; cleavage is perfect rhombohedral in three directions.
Where calcite comes from
The recognised sources are Helgustaðir, Eskifjörður, Iceland, Elmwood Mine, Carthage, Tennessee, USA, Egremont, Cumbria, England and Dalnegorsk, Primorsky Krai, Russia.
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 calcite is treated
Usually untreated as specimens, but massive calcite is widely dyed, and cheap 'blue onyx' and green 'ocean jasper substitutes' on the market are dyed calcite. Doubling seen through a cleavage rhomb is the classic teaching demonstration of birefringence.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What calcite is confused with
The usual confusions are Aragonite, Dolomite, Fluorite and Quartz (much harder, does not effervesce).
The separation is rarely a matter of opinion: refractive index 1.486–1.658 (birefringence 0.172) and specific gravity 2.69–2.71 settle most of it in a minute, and magnification settles the rest.
What calcite is used for
Calcite is bought by mineral collecting, carving and sculpture, architecture and interiors, decorative objects, wellness and body care, technical and precision components and heavy industry — 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 specimen, by the block or by the square metre.
Durability and care
Hardness 3; cleavage perfect rhombohedral in three directions. That combination decides what it can safely be set into.
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 calcite costs
Indicative pricing for calcite is Iceland spar rhombs $5–$80; fine Elmwood or Chinese crystal groups $100–$10,000.
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 calcite treated, and how?
Usually untreated as specimens, but massive calcite is widely dyed, and cheap 'blue onyx' and green 'ocean jasper substitutes' on the market are dyed calcite. Doubling seen through a cleavage rhomb is the classic teaching demonstration of birefringence.
Where does calcite come from?
Helgustaðir, Eskifjörður, Iceland, Elmwood Mine, Carthage, Tennessee, USA, Egremont, Cumbria, England and Dalnegorsk, Primorsky Krai, Russia. Origin affects price, so we name the locality rather than the country on every quote.
Is calcite hard enough to wear every day?
Not really. At 3 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 calcite cost?
Indicatively Iceland spar rhombs $5–$80; fine Elmwood or Chinese crystal groups $100–$10,000. 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 calcite confused with?
Most often Aragonite, Dolomite, Fluorite and Quartz (much harder, does not effervesce). A refractive index of 1.486–1.658 (birefringence 0.172) and a specific gravity near 2.69–2.71 separate it quickly.
What is calcite used for besides jewellery?
mineral collecting, carving and sculpture, architecture and interiors, decorative objects, wellness and body care, technical and precision components and heavy industry. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for calcite?
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 calcite