The facts
What nosean actually is
Mineralogically, nosean is sodalite group (feldspathoid) — Na₈Al₆Si₆O₂₄(SO₄)·H₂O, crystallising in the isometric system.
The colour is caused by grey-blue to near-black; colour largely from fine inclusions and sulphur species, not a simple chromophore. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.470–1.495, and the specific gravity sits near 2.30–2.40; cleavage is poor dodecahedral.
Where nosean comes from
The recognised sources are Laacher See, Eifel, Germany, Mount Vesuvius, Campania, Italy and Cabo de Gata, Almería, Spain.
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 nosean is treated
Untreated. Almost always opaque to translucent and collected rather than cut; rare transparent grains from the Eifel are faceted at under a carat.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What nosean is confused with
The usual confusions are Haüyne, Sodalite and Lazurite.
The separation is rarely a matter of opinion: refractive index 1.470–1.495 and specific gravity 2.30–2.40 settle most of it in a minute, and magnification settles the rest.
What nosean is used for
Nosean is bought by mineral collecting — 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.
Durability and care
Nosean is 5.5 on the Mohs scale, with poor dodecahedral 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 nosean costs
Indicative pricing for nosean is Micromount specimens 10–80 USD; faceted grains 100–400 USD/ct.
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 nosean treated, and how?
Untreated. Almost always opaque to translucent and collected rather than cut; rare transparent grains from the Eifel are faceted at under a carat.
Where does nosean come from?
Laacher See, Eifel, Germany, Mount Vesuvius, Campania, Italy and Cabo de Gata, Almería, Spain. Origin affects price, so we name the locality rather than the country on every quote.
Is nosean hard enough to wear every day?
Yes. At 5.5 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 nosean cost?
Indicatively Micromount specimens 10–80 USD; faceted grains 100–400 USD/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 nosean confused with?
Most often Haüyne, Sodalite and Lazurite. A refractive index of 1.470–1.495 and a specific gravity near 2.30–2.40 separate it quickly.
Related stones
Looking for nosean?
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 nosean