Gwrhyd Blue Pennant Sandstone from Rhiwfawr Quarry in the Upper Swansea Valley is one of the strongest available in the UK. The quarry is roughly 12 miles north of Swansea and not far from the small hamlet of Rhiwfawr and the outskirts Neath.
Its technical properties are far superior to other sources of pennant and allow it to be either used in thinner thicknesses compared to other stones or to carry higher loads. For instance a 400x900mm flag stone at 50mm in Gwrhyd Pennant will carry a class 5 loading as shown in the table below where normal pennant will only carry class 2.
| Class | Min Breaking Load kN | Typical Use |
| 0 | 0 | Decoration |
| 1 | 0.75 | Slabs bedded on mortar, pedestrian only. |
| 2 | 3.5 | Pedestrian and cycle areas. Garden Balconies. |
| 3 | 6 | Occasional car, light vehicle and motorcycle access. Garage entrances |
| 4 | 9 | Walking areas, market places occasionally used by delivery vehicles. |
| 5 | 14 | Pedestrian areas often used by heavy vehicles. |
| 6 | 25 | Roads and streets, petrol stations. |
All Gwrhyd blue pennant stone is tested to British Standards. This includes durability tests such as freeze thaw and flexural tests after freeze action. Beyond this our products are also tested for other durability indicators not covered in the British Standards such as polished paver test vales. This gives security that the product will be sound during service.
What you will see an abundance of marks made by animals that burrowed into the wet sand when it was the bed of a shallow sea or river. You can also clearly see the ripple marks caused by the action of the water. There are superb examples of this in the Gwrhyd Pennant Quarry sandstone paving at the entrance of National Waterfront Museum in Swansea.
This is a recent build completed in the Swansea Valley. The main build material was locally quarried 
Gwrhyd Specialist Stone Quarry was established in January 2000 when a magnitude of Blue Pennant sandstone was unearthed by the Davies’ on their family farm in the Swansea Valley.