AZUL – Blue-gray ornamental limestone varieties from Portugal

Blu & Bug Lime 09a
Beautiful block of Vidraço Ataíja Azul limestone (under the Portuguese unique blue sky).
There are several current varieties of grayish/blue limestone, all from the same general region of Portugal: the Mira de Aire and Candeeiros Range in the West of Portugal (the Azul Cascais limestone reserves nearby Lisbon are virtually depleted or inaccessible due to urban sprawl). Those varieties are:
  • Vidraço Ataíja Azul: Very hard compact limestone, finely calciclastic, occasionally with some stylolites and calcite veins. The Vidraço de Ataíja Azul limestone occurs associated with the Vidraço de Ataíja Creme (note bellow). It is not easy to find big blocks of this variety but it is an ornamental stone of  very good quality.
  • Moleanos Azul: Hard limestone with a slight greyish tonality, bioclastic, with oölitic tendency, abundantly spathized and showing disperse brownish nodules or fine spots occasionally with some thin calcite veins. The blocks extracted are of large size and the cutting of slabs is usually performed according to the bedding plane. This limestone occurs associated with the Moleanos Beije (again, note bellow). It´s normal to find invisible small cracks (popped). Very consistent ornamental stone.
  • Moca Creme Azul: Greyish/Beige limestone, coarsely calciclastic and abundantly bioclastic. The blocks extracted are of large size and the cutting of slabs is usually performed perpendicular to the bedding plane. Very consistent ornamental stone.
  • Azul Valverde: Bluish-grey limestone with disperse small stains of lighter tonality and coarse elements, calciclastic and little bioclastic. The extracted blocks are, usually, of large dimensions. Their sawing is performed according to the bedding plane. Some variation in color and texture is expected.

There is also a notable grey marble variety – Trigaches  – used at least since Roman times in the Iberian Peninsula, found in the South of Portugal (Alentejo, the land of famous marble, red wines, wide plains and friendly people – but that’s for another article). In the north and center of the country, there are also interesting grey ornamental granites (ye, you guesses, yet another post).

Blue-gray limestones are usually associated with crème (beige) varieties of the same stone with mixed color (malhado) blocks in the transition zone (crème limestone on top of the blue, the former due to water leaching of the latter).

A few days ago we went scouting for blue-gray limestone for a potential client. We have created a photo gallery with some of the quarries and blue (Azul) limestone varieties we found – if you are curious check it here or drop us a mail through our contacts.

Luís Chambel and Luís Caeatno

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Luís Chambel

Exploration & Research Mining Engineer, MSc Engineering Geology, MBA, PhD European Engineer -EUR ING; Euro Geologist - EURO GEOL

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