Emery

What emery actually is

The species behind emery is a naturally occurring abrasive rock - an intergrowth of corundum with magnetite, hercynite spinel and hematite, Corundum Al2O3 with Fe3O4, FeAl2O4 and Fe2O3; it forms in the aggregate system.

Black to dark grey from the iron oxides; the corundum itself is grey-blue 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 1.76-1.77 (corundum) and a specific gravity of about 3.70-4.30, with none; corundum shows parting cleavage.

Where emery comes from

Commercial material comes from Naxos (Apiranthos and Koronos), Cyclades, Greece - the classical source, mined since antiquity, Aydin and Milas districts, Turkiye, Peekskill and Westchester County, New York, USA and Chester, Massachusetts, USA (historic).

Different localities give different colour and different clarity, and the trade prices them differently. We state which one.

How emery is treated

Crushed and graded, nothing more. LEGAL AND HISTORICAL: Naxos emery is a Greek state monopoly, with extraction rights historically vested in the local community of emery workers and production now minimal - the material is close to a heritage commodity. Emery has been almost entirely displaced by manufactured aluminium oxide and silicon carbide, so 'emery cloth' and 'emery boards' in shops today generally contain no emery at all. That name persistence is worth flagging honestly.

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 emery is confused with

Watch for Manufactured aluminium oxide and silicon carbide (what modern 'emery' products actually contain), Magnetite and ilmenite sands and Garnet abrasive — these are what turn up sold under this name.

The separation is rarely a matter of opinion: refractive index 1.76-1.77 (corundum) and specific gravity 3.70-4.30 settle most of it in a minute, and magnification settles the rest.

What emery is used for

The trades that buy emery are abrasives, heavy industry 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 tonne or by the specimen.

Durability and care

Emery is 7-9 (the corundum controls the cutting) on the Mohs scale, with none; corundum shows parting cleavage.

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 emery costs

Expect roughly $200-700 per tonne for graded natural emery; the market is now very small, 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.

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