Portoro Marble (black and precious)

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Portoro Black Marble

Portoro Marble (black and precious). Portoro was originally called “yellow and black mixture”, subsequently taking its name from the place where it was extracted, i.e., “Portovenere marble” (as you will see later in the article).

From a commercial point of view, Portoro is considered a marble even though it is actually a limestone with a microcrystalline structure. Portoro is a pure fine black limestone, characterized by yellow-reddish dolomitization veins.

The black color is due to the carbon particles, while the color of the veins is due to the small quantity of ochraceous-limonitic iron and small pyrite crystals.

Author’s note: extract from Sara Odino’s degree thesis (see final notes).

Portoro is a very valuable Italian black marble, that comes from the province of La Spezia (in Liguria) and, in particular, from the famous Gulf of Poets.

The Gulf is composed of towns such as Lerici, Portovenere, Manarola, Tellaro, the famous Island of Palmaria (just to name a few).

Due to its regal and elegant appearance, Portoro is certainly one of the most loved and requested black marbles in contemporary interior design projects. Particularly suitable for the creation of decorative elements, objects (like the vase below), sculptures, floors and, of course, coverings.

Click on the photo to see in detail this beautiful vase in black Portoro with yellow ochre veins.

The main characteristic of Portoro is the black background on which elegant and decorative yellow, orange or white golden veins emerge.

The difference in the color of the veins naturally depends on the quality of the Portoro marble taken into consideration: the more golden and coloured yellow or orange they are, the more valuable they are.

Portoro is a marble extracted mainly in the Portovenere area (in Liguria). So precious as black marble that it is called the black gold of Portovenere. Click on the photo above to enlarge it and see the particularity of the golden veins.

Portoro Polychrome marble

Portoro is considered the most expensive black marble in the world, as well as one of the most beautiful polychrome marbles among those in existence.

Polychrome marbles are those with multiple colors. Below is the definition taken from the Treccani online encyclopedia:

“A very valuable polychrome veined marble, which is obtained in the Portovenere area; it is a Rhaetian limestone with a black background and yellow veins, which takes the best variety of golden hues”.

I suggest you read some in-depth information on polychrome marbles, such as:

The colors of the ancient -at the Capitoline museums in Rome (link in italian).
Polychrome marbles (link in italian).
Finally, the beautiful study- The colors of marble: polychrome stones in Liguria between the 16th and 18th centuries by Roberto Santamaria (also downloadable in PDF format) taken from the Ministry for Cultural Heritage and Activities, State Archives of Genoa (PDF in italian).

In the photo above, you can admire a beautiful flower fountain with a torchon column and square base in Portoro black marble. Click on the photo to see the details of the fountain.

Returning to our story, it seems that black Portoro marble is almost 200 million years old (as reported on the Marmomac website) and since its availability is limited, it is very valuable (in fact it is placed in third place in the marble category) .

The black color is given by a large amount of organic substance. The golden streaks, however, are due to a partial dolomitization process which destroyed the organic substance by oxidizing it.

Author’s note: to better understand the dolomitization process, read the interesting article by geologist Mauro Carta that you will find at the link above.

Portoro: characteristics of black marble

One of the fundamental characteristics of Portoro marble – in addition to the golden veins that range from pure yellow to the color of honey – is the background color which must be as dark as possible until it reaches the so-called “sepia black”.

Author’s note: Squid ink is the dark liquid, also called ink, that cuttlefish and other cephalopods secrete.

Upon fracture, Portoro is hard and compact and allows a good degree of polishing given its compactness.

A black color so intense and brilliant that anyone who sees a slab of polished black Portoro marble will be left speechless and literally fascinated (it does not have that intense and brilliant characteristic when freshly extracted, on the contrary, it seems grey).

This characteristic is typical of all the Portoro black marble that Bemarmi has in stock (a Carrara company) and significantly changes the optical effect of the material itself at the time of polishing and installation.

There is the broad spot Portoro (the most famous and prized) and the fine spot Portoro.

Both varieties of Portoro (fine spot and broad spot) increase in value where the yellow veins prevail over the white, although the varieties with yellow and white spots are, at times, much more resistant.

Author’s note: extract from Sara Odino’s degree thesis (see final notes).

The port in ancient times

Portoro had great success in the 20th century but it has always been a marble used since ancient times. As already specified several times in this same article, the particularity of its appearance makes it a unique marble, irreplaceable as an ornamental material.

There is no similar stone in the world, equally characteristic and so luxurious and sophisticated.

Portoro is a true work of art of nature, before which it is impossible not to be enchanted. The first time you see this marble, one is left speechless by its beauty.

“This marble, probably already used by the Etruscans, was used in the Roman city of Luni (link in italian) in the paving of the Roman road of Cardo-Maximum and in the Amphitheatre (Pandolfi, 1971). The Romans initially used portoro only as a building material but then also used it in more demanding works and in private construction in natural or polished slabs for coverings or floors”.

Author’s note: extract from Sara Odino’s degree thesis (see final notes).

We find Portoro marble in the imperial villas of ancient Rome and we also find it in the most luxurious buildings of the Renaissance, in Roman churches and in the most luxurious European palaces of the 19th century.

During this period, it was used mainly in Switzerland, Belgium and France, where in particular, it was used in Versailles.

“In the Renaissance era there was a return to the use of marble following the rediscovery of classical taste. During the reign of Cosimo I de’ Medici there was a great impulse towards the research and extraction of polychrome marbles such as Giallo Siena, Brecce Medici and Portoro. Various examples can be found in Italy and Europe, including in the Baroque period.”

Author’s note: Wikipedia source (see final notes).

“In Rome it was used for the interiors (floors and altars) of various churches such as San Pietro in Vincoli, San Silvestro in Capite, San Paolo Outside the Walls, San Giovanni in Laterano, San Lorenzo Outside the Walls, Santa Maria Maddalena in Campo Marzio, Santi Giovanni e Paolo, San Luigi dei Francesi”.

Author’s note: Wikipedia source (see final notes).

At the next link you will find an interesting article which talks about the “treasure of Portovenere“, aka the black Portoro marble. You will also find some brief historical notes.

Portoro: Beautiful and elegant black marble

Portoro marble has been used for centuries in all high-level workmanship and in ultra-luxury coverings. In fact, we find it in the most beautiful historic Italian buildings.

Portoro is a stone of great beauty suitable for interior furnishings.

Its originality and elegance make it one of the best stones suitable for fine coverings, including floors, vertical coverings, false ceilings, walls and decorative accents. As well as for many modern furnishing accessories: fireplaces, columns, sculptures, tops, and more.

Portoro black marble amazes in interiors, bathrooms, kitchens, worktops, showers and water areas. Widely used in inlays, for the contrast created by the combination of light marbles such as: white Carrara marble, Carrara arabesque, Norwegian pink, Siena yellow, Sicilian pearl and many others.

Portoro black marble table inside the Capitular Tower of Portovenere. Click on the photo to see the details of the Portoro table.

Due to its extraordinary beauty, Portoro black marble is particularly loved and used by the most important architects and interior designers around the world. Nero Portoro marble has been used in projects of large buildings, towers, shopping centers, hotels and luxury villas in every part of the planet.

Portoro: The true Made in Italy

Made in Italy stands out in many typically Italian products: Ferrari, pasta, pizza, the Renaissance, Leonardo da Vinci, and more.

We can certainly say that Portoro black marble is something unique.

A true jewel of Made in Italy. Something that only Italy can boast of having. Indeed, to be honest, a jewel of nature that only the Portovenere area (in the province of La Spezia) can boast about.