1 Geography / Geology

 N.V. Calcaire de Vinalmont quarries a blue stone called “MAASKALKSTEEN – STEEN VAN VINALMONT” in Vinalmont. The quarry is located in Vinalmont, in the Fonds du Roua valley, west of downtown Vinalmont, on the northern flank of the Namur Synclinorium. Lambert coordinates: N 50° 34’ 6’’ E 5° 12’ 10’’.

The material is used as a building stone and masonry stone. The quarry yields a compact, fine-grained, non-porous limestone, ranging in color from pale gray to gray-beige on a sawn surface to dark gray on a fresh fracture surface. The stone develops a light gray patina that is characteristic of this material. The quarried layers are located on the northern side of the Namur Basin, east of the Mehaigne River, and form the Neffe Formation, dating from the Upper Moliniacian to the Visean (V2a) series—Mississippian, Lower Carboniferous.

The massive rock is cut through by three sets of joints, running nearly perpendicular to the bedding planes. Mining takes place in open-pit operations; the seams strike approximately N72°-81°E and dip 5°-10°S.

The total exploitable thickness in a single section is approximately 38 m. The approval applies to those parts of the quarry that are of comparable quality, i.e., the homogeneous, light-gray massive bank 30 m thick with few stylolites, which is pale gray in color and clearly indicated on the cross-section (see p. 5, Appendix 1, geological cross-section). These strongly serrated stylolites (electrocardiogram shape) are characteristic of Vinalmont stone. When they are intergrown and closed, they allow for quarrying both perpendicular to the bedding (cross-cut) and parallel to the bedding (longitudinal cut).

Veins that are poorly joined and very fine (less than 0.1 mm) should be rejected, as they form preferred fracture planes in the rock. These fractures typically occur during the processing of the rock.

2 Petrography / Lithology

 Macroscopic description: “MAASKALKSTEEN – STEEN VAN VINALMONT” is a chemically very pure, oolitic, compact limestone of sedimentary origin, with a homogeneous texture exhibiting cross-bedding, which is revealed by the patina. The color of the stone ranges from pale gray to gray-beige on a sawn surface and dark gray on a fresh fracture surface. The stone develops a light gray patina that is typical of this material. This patina, which results from aging and is inherent to the rock’s composition, must be taken into account during restoration work. The limestone contains fragments of corals (some beds are rich in Siphonodendron-type corals) and shells of brachiopods and gastropods.

According to PTV 819-4, ‘Classification of Rocks for the Purpose of Type Approval with Reference to EN 12670,” this is a sedimentary carbonate rock—oolitic limestone: 2.2.1.3.

Microscopic description: “MAAS LIMESTONE – VINALMONT STONE” is an oolitic bioclastic limestone rich in pellets. The rock consists primarily of a fauna rich in microfossils, of which the foraminifera are diagnostic for its age, and with a packstone to grainstone texture (DUNHAM classification) or a biosparite to biomicrite (FOLK classification); see EN 12670. Other lithological features may be present.

Composition (for informational purposes): The average composition is 99% calcium carbonate (CaCO3), 0.5% to 1% silicon (SiO2), and iron, manganese, and magnesium oxides.