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Nero Marquina

The close-up view of each stone type shows a relatively true image of the crystalline structure and the colouring. This is suitable for grained slabs to a limited extend only. In regard to the colour matching, please take an original sample of the stone from your furniture store as a basis.

Petrography

Dense, black limestone not in layers is crossed irregularly by numerous white calcite veins. Different wide cracks were generated by tectonic faults, filled by circulating solutions in the form of calcite. As the pigments (Organic carbon) did not dissolve, the veins remained white and formed an extreme colour contrast. Fossils fractures are no longer visible. Nero Marquina belongs to the bituminous lime as it contains black minerals like carbon or bitumen (Generated from sludge). 

Petrogenesis

Black limestone was generated in estuaries of the sea near the coast (brackish water area) with bad ventilation but with a large growth of plants and plankton. Dead plants and animals did not decompose due to the low oxygen content but were covered by clay and lime sediments. Bituminous materials were generated under pressure and high temperatures causing the black colouring of the rock. In the case of extreme enrichment of such organic material this geo-chemical process can lead to oil forming.

Hardness Soft Stone
Structure Type Slab with Irregular Pattern
Synonyms Black Marquina, Negro Bilbao, Spanisch Schwarz
Group Sediment rocks
Petrographic Assignment Limestone
Age 330 million years (Carbonic)
Colouring Minerals White calcite coloured black by bitumen
Average Hardness Approximately 3-4 (According to Mohs's hardness scale 1-10)
Deposit Spain, north of Bilbao/Marquina