The facts
What nuummite actually is
Mineralogically, nuummite is anthophyllite–gedrite rock (amphibole group) — □Mg₇Si₈O₂₂(OH)₂ with Mg₅Al₂Si₆Al₂O₂₂(OH)₂, crystallising in the orthorhombic (intergrown aggregate) system.
The colour is caused by dark grey-black body from Fe; the red, gold, green and blue iridescence is thin-film interference from exsolution lamellae between the two intergrown amphiboles. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.635–1.663, and the specific gravity sits near 3.18–3.37; cleavage is perfect amphibole cleavage in the component crystals.
Where nuummite comes from
The recognised sources are Nuuk (Nuummiut), Sermersooq, Greenland.
That is the whole list. A single source makes supply fragile and makes any claim of a second origin worth questioning.
How nuummite is treated
Untreated; the iridescence is structural. Some material is resin-stabilised. Anthophyllite is a regulated asbestiform amphibole, so only the massive non-fibrous rock is worked. Greenlandic export is controlled.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What nuummite is confused with
The usual confusions are Labradorite, Nuummite imitations in coated glass, Astrophyllite and Rainbow obsidian.
The separation is rarely a matter of opinion: refractive index 1.635–1.663 and specific gravity 3.18–3.37 settle most of it in a minute, and magnification settles the rest.
What nuummite is used for
Nuummite is bought by jewellery, carving and sculpture, decorative objects and 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 carat, by the block or by the piece.
Durability and care
Nuummite is 5.5–6 on the Mohs scale, with perfect amphibole cleavage in the component crystals cleavage.
Hardness is not the whole story. Perfect cleavage means the stone can split cleanly if struck along the wrong plane, whatever its Mohs number, so a protective setting matters more here than the hardness suggests.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What nuummite costs
Indicative pricing for nuummite is $2–40/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 nuummite treated, and how?
Untreated; the iridescence is structural. Some material is resin-stabilised. Anthophyllite is a regulated asbestiform amphibole, so only the massive non-fibrous rock is worked. Greenlandic export is controlled.
Where does nuummite come from?
Nuuk (Nuummiut), Sermersooq, Greenland. That is the only commercial source.
Is nuummite hard enough to wear every day?
With care. It is 5.5–6 on the Mohs scale, which is hard enough, but perfect amphibole cleavage in the component crystals cleavage means it can split if struck at the wrong angle. Use a protective setting and avoid ultrasonic cleaning.
How much does nuummite cost?
Indicatively $2–40/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 nuummite confused with?
Most often Labradorite, Nuummite imitations in coated glass, Astrophyllite and Rainbow obsidian. A refractive index of 1.635–1.663 and a specific gravity near 3.18–3.37 separate it quickly.
What is nuummite used for besides jewellery?
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 nuummite?
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 nuummite