R10
0.1 weight %
3.02 CO₂-EQ
47.6 MPa
A brushed, completely smooth surface in a grey tone with distinct natural variation and three-dimensional depth.
The slate is quarried from a large deposit in the bedrock between Rönnöfors and Finnsäter, near the border between Norway and Sweden. The deeply brushed surface highlights the stone’s minerals and gives it a lighter grey tone with a sense of richness and depth. The even surface makes the slate easy to clean. Brushing, as well as final processing of dimensions and thickness, is done locally at the quarry to ensure consistent quality and a minimal climate footprint.
| min – max (mm) | min – max (mm) | min – max (mm) | |
| Length | Width | Thickness | |
| Rectangular, random lengths | 300 – 2500 | 100 – 600 | 10 – 50 |
| Rectangular, fixed lengths | 300 – 2500 | 100 – 600 | 10 – 50 |
| Square | 100 – 600 | 100 – 600 | 10 – 50 |
| Sawn | |
| Brushed | |
| Honed |
| Tiles for walls and floors (indoors) | |
| Tiles for walls and floors (indoors) | |
| Outdoor tiles | |
| Pedestal tiles for raised flooring | |
| Stair treads | |
| Benchtops and hearths | |
| Façade panels | |
| Window sills |
| mm | |
| Thickness/depth | |
| Indoor floor/wall | 8 – 20 |
| Raised floor (indoor/outdoor) | 20 – 25 |
| Outdoor glued paving | |
| Pedestrian traffic | 10 – 20 |
| Façade panels | 8 – 35 |
| Glued to steel/aluminium profiles | 8 – 15 |
| Slate overlap with screws or hooks on steel/aluminium/timber battens | 8 – 15 |
| Mechanically fixed on back side to profiles | 15 – 25 |
| Mechanically fixed with dowels in slate edge to profiles | 32 – 35 |
| Thickness [mm] | Weight per m² [kg] |
| 10 | 27 |
| 12 | 33 |
| 15 | 40,5 |
| 20 | 55 |
| 25 | 67,5 |
| 30 | 81 |
| 40 | 108 |
| 50 | 135 |
| 60 | 162 |
| Density | 2740 g/m3 |
| Water absorption [weight %] | 0,1 |
| Flexural strength [MPa] | 47,6 |
| Slip resistance | R10 |
| CO₂ emissions [kg eq. per m², t: 12 mm] | 3,02 |
| The mineral composition explains the technical performance and uniform appearance of Offerdal slate. This is a fine-grained quartzite slate with high mica content and low porosity, resulting in excellent dimensional stability and durability. | |
| Quartz | 39% |
| Provides high abrasion resistance and low water absorption. | |
| Mica | 42% |
| Influences cleavage and surface; gives a homogeneous, fine-grained appearance. | |
| Feldspar | 8% |
| Contributes to colour tones and increases chemical stability. | |
| Epidote | 2,5% |
| No visible or technical impact at this content level. | |
| Plagioclase | 2,2% |
| Part of the grain structure, with no significant effect on performance. | |
| Ilmenite | 1,2% |
| Present in small quantities. No practical relevance for appearance or properties. | |
| Zircon | 0,2% |
| Trace element with no functional or aesthetic impact. | |
| Calcite | 0,1% |
| Negligible for technical performance; content low enough to prevent acid sensitivity. |
| Petrography | |
| Quartzite slate | |
| Origin | |
| Offerdal, Krokom Municipality, Sweden | |
| Material descriptions for façades and flooring, indoor and outdoor: | |
| Medium-grey quartzite slate in natural layers with a matte finish. The appearance is achieved using planed and brushed surface treatment in multiple steps with various tool grades. | |
| Cleavable natural stone with visible layering or zones showing different colour nuances | |
| A certain variation in grey tones from tile to tile is desirable for a natural, vibrant expression | |
| Flexural strength above 45 MPa | |
| Water absorption max 0.1% | |
| Slip resistance minimum R9 | |
| Durable and long-lasting | |
| Long-term supply and documentation assurance: | |
| EPD for life cycle analysis and carbon calculations | |
| Proven performance over time, including under patina development | |
| Reuse potential (provided functional criteria otherwise allow it) | |
| Long-term operational plans | |
| Future availability of same visual expression and technical quality | |
| Established routines for testing and control | |
| CE marked | |
| Reference projects | |
| Access to technical support and project advisors | |
| Other material requirements: | |
| Must be a natural material | |
| Should reflect the project’s history and/or location | |
| See also reference projects for intended visual expression |
Place of origin Offerdal, Krokom Municipality, Sweden Petrography Quartzite slate
Offerdal silkebrushed surface: Medium-grey quartzite slate in natural stratifications with a matte surface. The expression is achieved with a surface planed and brushed in multiple steps using tools with varying abrasiveness.
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