Feldspar
Feldspar (silicate, chemical formula Na(AlSi3O8), where Na can also be replaced by K) is one of the main constituents of the Earth’s crust. Feldspar can be characterised by:
- Relatively high Mohs hardness of 6
- Low electrical conductivity
- Easy to wet
- High inertness in various media.
And, depending on the grade:
- Low content of lamellar mica
- Low fine crystalline silica fraction (no labelling)
- Whiteness
Note when using feldspar: depending on the particle size distribution of certain products, they can be labelled STOT RE 2. For more detailed information, visit www.safesilica.eu.
Sibelco feldspar quarry in Cine (Turkey)
Basic properties
| Property | Value | Unit |
| Moisture | < 0.5 | [%] |
| Hardness (Mohs) | 6 (6.5) | [-] |
| Refractive index | 1.53 | [-] |
| L.O.I. | 0.5 | [%] |
| Density | 2.6 | [kg/ dm3] |
Product overview
| Product | Grade | D50
[µm] |
D97
[µm] |
OA
[g/ 100 g] |
pH | L* |
| Feldspar | FF-20 | 6 | n.d. | 32 | 9.8 | |
| FF-30 | 8 | n.d. | 28 | 9.7 | ||
| FF-60 | 19 | n.d. | 27 | 9.5 | ||
| FF-150 | 23 | n.d. | 24 | 9.4 | ||
| PG4 | 4 | 17 | 26 | 9.5 | 94.5 | |
| PG W7 | 7 | 25 | 27 | 8.0 | 97.0 | |
| PG W13 | 13 | 60 | 22 | 8.1 | 96.4 | |
| PG W20 | 20 | 80 | 19 | 8.2 | 96.2 |
Production locations Feldspar
Application
Feldspar will provide:
- Chemical resistance: due to its inert nature, feldspar provides good chemical resistance compared to conventional fillers.
Advantage over quartz and cristobalite: several feldspar grades are free of labelling, and can therefore be used as an alternative when fine quartz or cristobalite grades are no longer allowed.
Durability
