Creative valorization of the peculiarities and choices of bluestone that are rejected for traditional applications


The Belgian subsoil consists mainly of sedimentary rocks, often of marine origin. This is also the case for blue stone, also known as "petit granit", which can be found in the region of Soignies. This limestone is dotted with small crystallized fossil remains that shine like granite crystals when broken. Because of its natural origin, the particularities vary in size, shape, etc. For technical and aesthetic reasons, and given the strict selection criteria of Carrières du Hainaut, certain stones are rejected for traditional applications.



What choices and particularities are rejected for the usual sales channels?


BBRI states that only Belgian blue stone is subject to the specific criteria relating to the physical characteristics and defects that result in scrap.


Not allowed in traditional applications :


  • geodes (cavities which are covered with crystals)

  • black veins or noirures (cracks filled with carbonaceous material)



Permitted defects - in different quantities admitted based on the aesthetic criteria prescribed per category:


  • sponges (asteractinella)


  • fossils



  • white spots

  • white veins, not retaining water


  • shells zones



If you would like to visit the quarry of Carrières du Hainaut to get a better idea of the different choices and applications, please contact Mr. Philippe Sequaris (+ 32 (0) 67 34 78 00) for an appointment.


If fossils would be allowed without restrictions, a large cluster of shells at a particular place of the slab could results in a lack of uniformity of color or appearance. Therefore, the stone can also be removed out of the cycle due to an aesthetic point of view.

A large part of the normal production can be valorized, but keep in mind that we cannot guarantee the constancy of the material and its peculiarities. Each boulder is natural and unique. Carrières du Hainaut wants to valorize a quantity of the rejected material.


Reasons for rejection :


1. Shape, size and quality of the material

- Blocks <1m³

- Sawn or coated slabs, rejected due to sales criteria

- Waste or residu of finished products (tiles, cobblestones, customization)


Tranches écartées car non conformes aux critères de vente ou de valorisation classique (de 1.5cm à 30cm)Rejected slabs that don’t meet the sales criteria or classic valorization (from 1.5 cm to 30 cm)

Some awesome textThe refuse heap: Rejected slabs that don’t meet the sales criteria or classic valorization (from 1.5 cm to 18 cm)













Some awesome textCutting waste of cobblestones (thickness: 5 to 10cm) sawn sides and cut or split edges

Some awesome textCutting waste of cobblestones (thickness: 5 to 10cm) sawn sides or with a mechanical finish (dimpled, bush hammered) or flamed with cut edges

















2. aesthetically

- Large veins

- White spots

- Large fossils

- Strong concentration of fossils


3. Technical quality

- Large size of noirures

- High-density of noirures on slabs


The peculiarities of the stone should be taken into account before the application is determined. For example, a stone with noirures has a certain porosity which cannot be accepted for outdoor use, in bathrooms or kitchens as worktop. If these carbon spots hold water, they can cause cracks after a frost or deterioration of the stone.

Architects and artists already use certain stones that are rejected. For example, there are blue stone slabs where the noirures have been excavated and these voids are then filled with a gold-colored liquid. The imperfection of the stone is not hidden, on the contrary, an emphasis is placed upon it in order to make an original wall. The irregular crust plates with pronounced relief are already exploited. The brutal aspect of the stone seduces nowadays more often.


Identification and labeling


Exceptional choice:

The stone is perfect. No noirures.


Superior choice:

Contains beautiful material, even though there are fine veins and a small quantity of noirures (<15% of the surface of the slab)

Current choice:

The ratio of noirures rises to more than 30% or the vein is more pronounced


“D” choice:

The ratio of the noirures is more than 30% and the vein is more present or there are multiple veins present

Note: for this competition, only projects, which use the 'D' choice and / or the cutting waste of the different choices will be considered.

Carrières du Hainaut traces their material - from block to finished product. If in the future a new use of the materials that are today rejected is found, a new category of slabs can be created. This category can be separately classified in order to meet specific requirements.



Carrières du Hainaut's finishes