Nero Black Marquina Marble

Detailed Specifications

Nero Marquina is a black stone from the Basque Country of northern Spain, quarried at Markina-Xemein in the province of Bizkaia. Geologically it is not a metamorphic marble but a fine-grained bituminous limestone, classified petrographically as a dark, compact biomicrite with irregular white veins. The black comes from bitumen and carbonaceous matter dispersed through a calcitic matrix that was laid down in a low-oxygen marine basin; the white markings are later recrystallised calcite that filled tectonic fissures, which is why they form a criss-crossing network rather than the parallel bands of a wood-grain marble, and why fossil traces occasionally appear in the face. Most trade and academic sources place the deposit in the Cretaceous; some supplier pages say Jurassic or Carboniferous, so treat the exact age as unsettled.

That composition sets the rules for using it. It is a carbonate stone, so it etches on contact with acid, and its calcite-dominated mineralogy makes it etch faster than a dolomitic marble. Its flexural strength — the figure that governs how it behaves as a thin tile or a long span — is modest, so thickness and support matter. In exchange it is dense, takes a very high polish, and is one of the few black stones whose veining is genuinely white rather than grey.

Specifications

A Limestone Sold as Marble — and Where Your Blocks Come From

Nero Marquina is not a metamorphic marble. Its own quarry operator calls it la caliza ornamental conocida como Mármol Negro Marquina — the ornamental limestone known as Black Marquina marble — and petrographic work to UNE EN 12407 classifies it as a dark, compact, fine-grained biomicrite with irregular white veins. The black comes from bitumen and carbonaceous matter dispersed through a calcitic matrix laid down in a low-oxygen marine basin; the white markings are calcite that later filled tectonic fissures, which is why they criss-cross rather than running in the parallel bands of a wood-grain marble. Most academic and trade sources place the deposit in the Cretaceous; some supplier pages say Jurassic or Carboniferous, so treat the age as unsettled and "bituminous limestone" as the reliable description. The distinction is commercial: a specification calling for a metamorphic marble can fail on a laboratory report, and no supplier can claim metamorphic hardness for this stone.

The quarry is at Markina-Xemein in Bizkaia, in the Basque Country of northern Spain, on the ridge it shares with Aulesti. Production is concentrated in a handful of operations dominated by two names, Marnemar and Canteras Olaspe, whose Monte Zapola concession dates from 1988 — and the deposit is small enough for supply to be genuinely exposed: Canteras Olaspe's working face collapsed in September 2017 and took about three years to return to normal production. One operator states that its quarries produce 80% of the Negro Marquina sold worldwide, with reserves of roughly 80 years; that is the operator's own marketing figure, and one 2016 trade estimate put output of the genuine Spanish stone near 10,000 m² of slabs a month. Few faces, one dominant producer, limited tonnage — book the lot early on large projects.

Similar-looking black marble with white veining is also quarried in Morocco, Mexico and Iran under the same name, and the name travels further than the stone: Black Marquina, Black Marquinia, Negro Bilbao, Nero Markina, Noir Marquina — and in Chinese, 黑白根, "black-white root". Mislabelling is endemic, with public listings showing Markina, Spain in the description and China in the origin field. Make origin a written term, name the country and province (and quarry where known), require photographs or video of the actual lot rather than catalogue images, and obtain an origin certificate for Spanish material.

Reading the Veins: How This Stone Is Really Graded

The white veining is also the grading axis. The Spanish material is traded in three varieties defined by calcite vein density — low, medium and high, the heaviest sold separately as Negro Marquina Florido — and on top of that sits a two-tier quality split that buyers meet constantly. First Selection is deep, uniform black with sparse, clean veins and few fossils, in limited supply at a premium. Commercial Selection has a less deep and less uniform background, shade variation across the slab, more fossil content, and veining that trade sources describe as often covering more than half the slab face. Same stone, same deposit, very different appearance and price. Ask which one is being quoted, in writing, and approve the actual lot rather than a catalogue image of the top grade.

Because the veins are calcite-filled fractures, they are planes of weakness rather than decoration: cutting and profiling chip or open along them, so the trade works this stone in several light passes and hones wet rather than dry, since dry honing gouges the softer vein material and leaves veins sitting below the polished face. The same geology explains mesh backing — factories vacuum-epoxy resin and apply fibreglass mesh to the back to stabilise micro-fissures so the stone survives sawing and shipping. Check background tone in daylight, where charcoal grey reads as black under factory lighting. No universal grading standard exists, so require the grade designation in writing; China's GB/T 19766-2016 does set measurable limits and is worth quoting in a Chinese supply contract, as set out on our Black Zebra marble page.

Fabrication, Finish and Where Black Marquina Fails in Service

Finish decides how much maintenance the stone will demand. A polished black face is a mirror, and mirrors show everything — dust, fingerprints, water spots, grout haze and fine scratches all read more strongly on polished dark stone than on any other finish. Trade guidance converges: honed, typically 400 grit, for floors and vanities; polished for wall cladding where the deepest black is wanted and nothing walks on it. Honed hides the dull patches left by etching far better than gloss, and leathered better still.

Etching deserves a plain statement, because it is the most common complaint about black marble in service. This is a calcite-dominant stone, and calcite marble reacts with 1 M hydrochloric acid roughly 650 times faster than dolomite marble at 25 °C, so acidic cleaners, wine, vinegar, citrus and tomato leave dull marks, and no penetrating sealer prevents it — a sealer slows staining, not the reaction that removes the polish. On black stone an etch appears as a pale, milky patch, more visible than on white marble, and honing does not camouflage it the way it does on light stone, though it is far less glaring than on a polished face. Reseal roughly every 12 months in humid or coastal environments, every 18–24 months inland, clean with pH-neutral products only, and avoid hydrogen-peroxide poultices on dark marble because they lighten it. See Stone Finishes Compared and the Stone Sealing Guide.

The number that governs how this stone behaves as a tile or a span is flexural strength, not compressive strength. Published flexural results run from 12.0 ± 3.0 MPa by UNI EN 12372 to 13.3–14.4 MPa by UNE-EN 12372, falling to about 9.8 ± 2.3 MPa after 48 freeze-thaw cycles — low for a dimension stone, and the reason edges chip and strips snap in transit. Specify 18–20 mm for worktops and vanities rather than 10 mm, and keep unsupported overhangs short. Compressive strength is published in two irreconcilable families, 61.7–62.9 MPa by UNE-EN 1926 against roughly 107–121 MPa elsewhere; sources vary, so test the batch rather than trusting a datasheet.

On kitchens the trade consensus is blunt: Nero Marquina is generally discouraged for countertops, because acidic food, knives and cookware produce rapid etching and scratching. If a client insists, use honed and record their acceptance of ageing and wear; Absolute Black or Zimbabwe Black granite, or an engineered quartz replica, are the honest alternatives where the surface must survive daily cooking. Exteriors are genuinely contested — the stone passes EN 12371 and has real historical use in Spain, but one major tile manufacturer rates it for covered exterior walls in non-freezing climates only and warns that its iron minerals can bleed with moisture, while other trade sources rule it out for freeze-thaw-exposed facades. Interior work, plus covered and drained mild-climate exteriors, is the defensible line. Flamed finishes are not used on this stone; bush-hammered is the traditional textured answer.

Specifying and Inspecting a Nero Marquina Order

Name what the trade leaves vague. In the purchase order: origin (country, province, quarry where known, plus an origin certificate for Spanish material); grade and vein-density class, matched to a physically approved sample; finish and thickness with tolerance stated as ±1 mm commercial or ±0.5 mm for tiles; a target gloss of 85° or better on polished material; block-lot reservation with sequential slab numbers, and consecutive A/B cuts from one block if the design is bookmatched; a maximum acceptable crack length and chip size; and a batch test report for absorption and flexural strength on the material actually loaded. Approve the dry-lay or bookmatch before packing, and inspect before the container is sealed — the last point at which replacement is still cheap.

Mesh backing is standard here, not a defect, but it raises two questions: whether the resin was applied for structural or purely cosmetic reasons, and whether the backing is cement-compatible for your fixing method. The resin's waxy surface means adhesive bonds to the backing rather than the stone, and there is a documented failure mode of mesh-backed tiles debonding at the mesh-to-tile interface, with wet-set work sometimes requiring the mesh to be removed. For external cladding, BS 5385: Part 2 rules resin mesh-backed stone out entirely. Our Stone Defects and Inspection Guide shows how to record mesh encapsulation and delamination in an inspection report.

On price, be sceptical of anything published. There is no reliable public FOB number for genuine Spanish material; the solid European datapoints are finished tiles at roughly €150–170 per m² ex-works in Italy and UK retail slabs near £282 per m² — both retail-side, finished figures, not quarry-gate prices. Marketplace listings for Chinese-origin Nero Marquina-type slabs cluster around US$15–30 per m² FOB Xiamen, with premium book-matched lots far higher, and listings at US$16–18 per m² claiming Spanish origin should be read as mislabelled; genuine Spanish stone does not trade at lookalike prices. Shipping to the United States, price the 25% Section 301 duty on Chinese stone products into the landed cost. The Marble Price Guide explains how to read a quote structured this way and Negotiating with Stone Suppliers covers the commercial levers.