The facts
What slate actually is
The species behind slate is metamorphosed shale, Quartz, muscovite, chlorite; it forms in the aggregate system.
Carbon, iron and chlorite 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 2.7–2.9, with perfect slaty cleavage — it splits into sheets cleavage.
Where slate comes from
Commercial material comes from Wales, UK, Rajasthan and Andhra Pradesh, India, Brazil and Spain.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
Is slate treated?
None.
That makes disclosure simple: there is nothing to declare. It also means a seller offering a "treated" version of this material is offering something else.
What slate is confused with
Watch for Phyllite and Schist — these are what turn up sold under this name.
Because the material is opaque, refractive index is no help. Specific gravity around 2.7–2.9, hardness of 3–4, streak and magnification do the work instead.
What slate is used for
The trades that buy slate are architecture and interiors, automotive interiors, kitchen and table, audio isolation, engraved signage, aquascaping and games and gaming. 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 piece or by the kilo.
Durability and care
Hardness 3–4; cleavage perfect slaty cleavage — it splits into sheets. 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 slate costs
Expect roughly $15–90/m², 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 slate treated?
None.
Where does slate come from?
Wales, UK, Rajasthan and Andhra Pradesh, India, Brazil and Spain. Origin affects price, so we name the locality rather than the country on every quote.
Is slate hard enough to wear every day?
Not really. At 3–4 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 slate cost?
Indicatively $15–90/m². 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 slate confused with?
Most often Phyllite and Schist. Since the material is opaque, separation relies on specific gravity near 2.7–2.9, hardness and magnification.
What is slate used for besides jewellery?
architecture and interiors, automotive interiors, kitchen and table, audio isolation, engraved signage, aquascaping and games and gaming. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for slate?
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 slate