Bluestone is a dense, dark-grey to blue-black limestone that is very hard and wear-resistant. The best-known type is Belgian bluestone (petit granit), quarried in Wallonia. Despite the name it is not granite but a limestone; in cross-section, fossil remains (crinoids) are often visible as light flecks.
Properties
- Hard and wear-resistant — suitable for heavily used areas
- Dense — absorbs little water and is therefore reasonably frost-resistant
- Limestone — sensitive to acids; vinegar and limescale removers attack the surface
- Workable surface — honed, sawn, bush-hammered, or polished for different looks
Application
- Thresholds and window sills — the classic use at doors and windows
- Stair treads and landings — wear-resistant and representative
- Floors — in halls, kitchens and monumental buildings
- Facade cladding and plinths — as a natural-stone finish
Points to watch
- Cleaning — use pH-neutral cleaners; never vinegar, descaler or aggressive cleaning agents
- Impregnating — an oil- and water-repellent treatment limits stains from grease, oil and moisture
- Efflorescence — freshly sawn bluestone may ‘bloom’ at first (white haze); this usually fades
Related terms
- Natural stone
- Limestone
- Threshold
- Granite
- Mohs hardness scale
Want to learn more about construction terms? Visit our knowledge base at fredsdiyplans.com.