The facts
What gneiss actually is
The species behind gneiss is high-grade metamorphic rock with a banded segregation of light feldspar-quartz and dark mica-amphibole layers, Quartz, feldspar, biotite, hornblende, garnet and sillimanite; it forms in the aggregate system.
Compositional banding; the aesthetic value is entirely in the fold patterns 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 specific gravity of about 2.65-2.85, with foliation, not cleavage cleavage.
Where gneiss comes from
Commercial material comes from Verzasca and Maggia valleys, Ticino, Switzerland, Karnataka and Tamil Nadu, India (sold as 'Kashmir White' and similar granites), Espirito Santo and Bahia, Brazil (many exotic 'granites' are migmatitic gneiss), Lewisian complex, Outer Hebrides, Scotland and Adirondacks, New York, USA.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How gneiss is treated
Resin-impregnated and mesh-backed as slabs; many of the dramatically patterned 'exotic granites' in the countertop trade are Brazilian migmatitic gneiss. Anisotropic strength along the foliation means slabs can be weaker in one direction, which matters for large unsupported spans. Not CITES.
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 gneiss is confused with
Watch for Granite (unbanded), Migmatite and schist and Porcelain slabs printed with gneiss patterns — these are what turn up sold under this name.
Because the material is opaque, refractive index is no help. Specific gravity around 2.65-2.85, hardness of 6-7, streak and magnification do the work instead.
What gneiss is used for
The trades that buy gneiss are architecture and interiors, heavy industry and decorative objects. 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 square metre, by the tonne or by the piece.
Durability and care
Hardness 6-7; cleavage foliation, not cleavage. That combination decides what it can safely be set into.
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 gneiss costs
Expect roughly $40-250 per square foot installed; exotic Brazilian gneiss at the top end, 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.
Questions
Is gneiss treated, and how?
Resin-impregnated and mesh-backed as slabs; many of the dramatically patterned 'exotic granites' in the countertop trade are Brazilian migmatitic gneiss. Anisotropic strength along the foliation means slabs can be weaker in one direction, which matters for large unsupported spans. Not CITES.
Where does gneiss come from?
Verzasca and Maggia valleys, Ticino, Switzerland, Karnataka and Tamil Nadu, India (sold as 'Kashmir White' and similar granites), Espirito Santo and Bahia, Brazil (many exotic 'granites' are migmatitic gneiss), Lewisian complex, Outer Hebrides, Scotland and Adirondacks, New York, USA. Origin affects price, so we name the locality rather than the country on every quote.
Is gneiss hard enough to wear every day?
Yes. At 6-7 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 gneiss cost?
Indicatively $40-250 per square foot installed; exotic Brazilian gneiss at the top end. 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 gneiss confused with?
Most often Granite (unbanded), Migmatite and schist and Porcelain slabs printed with gneiss patterns. Since the material is opaque, separation relies on specific gravity near 2.65-2.85, hardness and magnification.
What is gneiss used for besides jewellery?
architecture and interiors, heavy industry and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for gneiss?
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 gneiss