The facts
What refractory-Grade Bauxite actually is
Refractory-Grade Bauxite is classified as bauxite - an aluminium-hydroxide rock - selected for low iron and silica and calcined to a dense, hard, high-alumina refractory aggregate, with the composition Calcined to 85-90% Al2O3, chiefly as corundum and mullite, from gibbsite, boehmite and diaspore precursors. It crystallises in the aggregate system.
Colour comes from buff to dark brown from residual iron; irrelevant to function, which is also what a laboratory looks at when it is asked whether a colour is natural.
Specific gravity around 3.10-3.30 after calcination. Cleavage: none. Those three numbers separate it from most of what imitates it.
Where refractory-Grade Bauxite comes from
Refractory-Grade Bauxite is produced at Bonasika and Linden, Guyana - the historic refractory-grade standard, Shanxi, Guizhou and Henan Provinces, China - now the dominant supply, Para and Minas Gerais, Brazil and Australia and Guinea (mostly metallurgical rather than refractory grade).
The locality is part of the description, not a footnote — two stones of the same weight from two of these places are not the same stone.
How refractory-Grade Bauxite is treated
Calcined in rotary or shaft kilns at 1,500-1,600 C to convert hydroxides to corundum and mullite and shrink the grain to near-zero porosity. Uses: monolithic refractory castables, refractory brick, high-friction anti-skid road surfacing (a large and less obvious market), abrasive grain, and proppant. Chinese export policy and energy costs drive pricing for the whole sector, which is a real supply-security concern for European and North American refractory makers. The overwhelming majority of world bauxite goes to alumina and aluminium, not to refractories.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What refractory-Grade Bauxite is confused with
In the trade refractory-Grade Bauxite is most often mistaken for, or substituted by, Andalusite, kyanite and sillimanite refractories, Fused and sintered alumina, Chamotte / fireclay grog or Mullite.
Because the material is opaque, refractive index is no help. Specific gravity around 3.10-3.30 after calcination, hardness of 7-9 after calcination, streak and magnification do the work instead.
What refractory-Grade Bauxite is used for
Demand for refractory-Grade Bauxite comes from heavy industry and abrasives, which is why one price per carat never covers it.
We quote each application in the unit that trade actually buys in, by the tonne.
Durability and care
Refractory-Grade Bauxite is 7-9 after calcination on the Mohs scale, with none 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 refractory-Grade Bauxite costs
As a guide, refractory-Grade Bauxite trades around $350-650 per tonne for calcined refractory grade; high-alumina and low-iron specifications at the top.
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 refractory-Grade Bauxite treated, and how?
Calcined in rotary or shaft kilns at 1,500-1,600 C to convert hydroxides to corundum and mullite and shrink the grain to near-zero porosity. Uses: monolithic refractory castables, refractory brick, high-friction anti-skid road surfacing (a large and less obvious market), abrasive grain, and proppant. Chinese export policy and energy costs drive pricing for the whole sector, which is a real supply-security concern for European and North American refractory makers. The overwhelming majority of world bauxite goes to alumina and aluminium, not to refractories.
Where does refractory-Grade Bauxite come from?
Bonasika and Linden, Guyana - the historic refractory-grade standard, Shanxi, Guizhou and Henan Provinces, China - now the dominant supply, Para and Minas Gerais, Brazil and Australia and Guinea (mostly metallurgical rather than refractory grade). Origin affects price, so we name the locality rather than the country on every quote.
Is refractory-Grade Bauxite hard enough to wear every day?
Yes. At 7-9 after calcination 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 refractory-Grade Bauxite cost?
Indicatively $350-650 per tonne for calcined refractory grade; high-alumina and low-iron specifications at the top. 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 refractory-Grade Bauxite confused with?
Most often Andalusite, kyanite and sillimanite refractories, Fused and sintered alumina, Chamotte / fireclay grog and Mullite. Since the material is opaque, separation relies on specific gravity near 3.10-3.30 after calcination, hardness and magnification.
Related stones
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