Nero Marquina Marble is one of the most important Spanish rocks, known all over the world.
The quarries of this marble are located in the Basque country in the Markina area from where its name comes from. There are currently three different quarries there. Similar-looking stones are mined in Mexico and Morocco, but according to the opinion of experts in the field of acquiring knowledge about this stone – taking into account the strength of the material, the size of the blocks, and the gloss obtained during machining – the original Nero Marquina remains only one, the one in Spain.
Similar-looking limestone is also found in China, where local companies sell their material under the same name. The stones actually look similar, but the whole secret of the differences between these stones is hidden in the structure of the stone. The Spanish Nero Marquina is a more plastic material, more resistant to cracks and the gloss structure, after processing, is better visible on its surface. On the other hand, stone of Chinese origin is harder, but definitely more prone to cracks. Many stonemasons from around the world say that black marble from China is an incredibly problematic stone when working, starting with the first stage of cutting on machines, where the marble simply cracks.
The real Nero Marquina, which was originally known as Negro Bilbao or Negro Espanol, is an ornamental limestone with a very fine and dense and crystalline grain, a black background and abundant white calcite veins that contain fossil remains of gray color in various shades.
The uniqueness of this material also lies in the fact that no two blocks are alike, which means that every single slab is unique. It is this feature that gives it originality.
While different companies may use different names to try and differentiate their material, Nero Marquina can be broken down into three different varieties:
with a few white veins
with an average number of veins
with lots of veins
Quarrying is done in blocks of large dimensions and the sizes are not uniform, but blocks 2.4 to 3 m long, 1.4 to 2 m high, 1.5 m thick are more common. to the size of the blocks, it therefore tends to these dimensions and has no problem in obtaining the thickness size. The total production of this exclusive material is approximately 10,000 m2 per month.
Negro Marquina is mainly used indoors and sometimes outdoors as well. Polished and honed finishes are mainly used as interior walkways, floors, walls, steps, countertops and sinks. On floors it is usually combined with Bianco Carrara or Bianco Macael or other white limestone to create a very attractive contrast. However, the most common use is for walls. The grained finish is common in the Basque Country and is used for exterior paving and for wall cladding of building facades. A flame finish was not used. In the Basque Country, the material was used in the form of large blocks such as reefs and breakwaters.
Negro Marquina enjoys wide recognition around the world, it is exported to various countries in Europe, the United States, Canada and Arab countries.
This material, when used on floors with high humidity, loses its shine as a result of carbon decomposition. To avoid this problem, the material must be treated against moisture. In case of loss of shine, it can be re-polished.
Technical characteristics of Negro Marquina marble
– Density: 2.69 gr / cm3
– Absorption rate: 0.17%
– Porosity: 0.2% to 0.47%
– Compressive strength: 629 kg / cm2
– Bending strength: from 14.4 Mpa to 13.33 Mpa
– Abrasion resistance: 2.90 mm
– Impact resistance: 30 cm
– Micro-hardness on impact: 1333.33 Mpa
– Abrasion resistance: 19.8 to 21.5 mm
– Change in the modulus of elasticity after frost: 8.2%