Industrial Minerals
What it is
Feldspar is an alkali aluminium silicate and the most abundant mineral group in the earth's crust. In industry it is a flux: the alkalis lower the melting point of a glass batch or a ceramic body, which saves energy and brings the whole mix to vitrification together.
Why buyers specify it
- Potash grades for ceramics, soda grades for glass — we supply both rather than one as a compromise.
- Low iron, so it does not tint flint glass or a white ceramic body.
- Tight alkali consistency, which is what keeps a glass furnace stable.
- Supplied as lump, granule or powder to match how the plant feeds it.
Grades we supply
Grade names are ours; the fineness and the duty are what you match against your current material.
| Grade | Type | Form | Usually bought for |
|---|---|---|---|
| XP-200 | Potash (K₂O 10–12 %) | 200 mesh powder | Sanitaryware, tableware |
| XP-Lump | Potash | Lump / 20–60 mm | Ceramic plants that grind on site |
| XS-Glass | Soda (Na₂O 7–10 %) | 30–80 mesh granule | Container and flat glass |
| XS-325 | Soda | 325 mesh powder | Glaze, frit, abrasives |
Other finenesses and surface treatments are available against a firm enquiry. If you are switching from another supplier, send their data sheet and we will match the curve rather than the mesh number.
Typical analysis
Chemistry
| Component | Potash grade | Soda grade |
|---|---|---|
| SiO2 | 64 – 68 % | 67 – 71 % |
| Al2O3 | 17 – 19 % | 16 – 19 % |
| K2O | 10 – 12 % | 0.5 – 3.0 % |
| Na2O | 2 – 4 % | 7 – 10 % |
| Fe2O3 | 0.05 – 0.3 % | 0.05 – 0.2 % |
| CaO | 0.3 – 1.5 % | 0.5 – 2.0 % |
Physical properties
| Property | Typical range | Method basis |
|---|---|---|
| Specific gravity | 2.55 – 2.65 | — |
| Moisture as packed | ≤ 0.5 % | Powder grades |
| Residue on 200 mesh | ≤ 2 % | Powder grades, wet sieve |
| Mohs hardness | 6 – 6.5 | — |
These are typical ranges for feldspar, not a specification. The values that govern your order are the ones measured on your lot and printed on its mill test certificate. Ask for a sample and the certificate that goes with it before you commit a production trial.
Where it is used
Feldspar is not one product sold 3 ways — it is 3 different conversations about the same mineral. We supply it into glass, ceramics & sanitaryware and paint & coatings, and in each of those the grade that works is chosen for a different reason: fineness in one, brightness in another, oil absorption or purity in the next.
Each industry below has its own page on this site, written for the people who formulate in it rather than for a general reader. If you work in one of them, start there — it will tell you which feldspar grade we would quote for your application and what we need to know before quoting it.
- Glass — Alumina and alkali source; improves durability and working range.
- Ceramics & Sanitaryware — The principal flux in vitreous bodies and glazes.
- Paint & Coatings — Functional extender where hardness and chemical resistance matter.
Iron is the figure to watch. For flint glass and white bodies the Fe₂O₃ limit, not the alkali content, is usually what rejects a cargo. We quote against your iron ceiling and certify it per lot.
Packing
| Pack | Detail | Suits |
|---|---|---|
| 25 kg paper or PP bag | Palletised 40 bags per pallet, stretch-wrapped | Powders |
| 50 lb bag | US-standard weight where the plant prefers it | Powders |
| 1,000 kg / 1 MT jumbo bag | Four-loop FIBC with discharge spout | Powders, sand, granules |
| Bulk | Pneumatic tanker or loose in container, where volume justifies it | Sand, granules, lump |
Private-label bags with your own artwork are available from one container. How private label works.
Documents with every shipment
- Mill test certificate for the lot, with the measured values, not the range
- Certificate of analysis signed by the processing plant
- Safety data sheet in the US 16-section GHS format
- Certificate of origin and the commercial invoice and packing list
- Asbestos test report where the mineral and the application call for one
Related minerals
Need a price on feldspar?
Send the grade, the tonnage and the delivery ZIP code. Quote and free sample back within one business day.