What should you know about Spanish slates?

When choosing natural slate you are opting for the best roofing material: long service life, quality, ecology and beauty. But are all the slates the same? Where can you find the best ones?

What is Spanish slate?

Spanish slate is a foliated, metamorphic rock created from fine-grained sediments over the course of millions of years. Is mainly composed of quartz, sericite and minerals of the chlorite group. Unlike UK slate where we find a greater variety of colors, Spanish slate is usually black or gray.

The lithotype for spanish roofing slates is B1, which according to the International Classification of Slate for Roofs (IRSC) corresponds to an authentic black-gray slate, fine grain, homogeneous and with a high fissibility, which allows it to be exfoliated in fine and regular tiles.

Slate has a long tradition as a construction product. Its strength and outstanding resilience make it one of the most durable and versatile materials mainly used for roofing and cladding.

Today, most slate used in the UK has a Spanish origin and are used for high end projects, historical buildings, traditional pitched-roof housing and sustainable architecture.

Why Spanish slate?

Not all slates are all alike nor do they offer the same guarantees. Slate produced in Spain, unlike slate from other parts of the world like China or Brazil, is of tectonic origin. Recognized worldwide for its performance, Spanish slates stand out by their high quality and superb aesthetic finish.

Spain is the world’s first slate producer. The biggest and best reserves of tectonic natural slate in the world are found in the north of the country, an area with a strong mining tradition from time immemorial.

Natural slate is already one of the most renowned roofing materials, and more and more architects and housebuilders are using it for their projects. In this respect, Spain plays the world leading role. In fact, 90% of the slate sold in the world is Spanish!

Where are the quarries located?

In the north of the country, in the Galicia and Castile and León provinces is where the largest number of mining operations are found.

Spanish slate from the Orense area was formed from muds laid down over 450 million years ago and was metamorphosed 300 – 350 million years ago. These deposits are found on slate formations of the middle and upper Ordovician. The most important are the geological structures of the Truchas synclinorium (Orense and León) and the Caurel syncline (Lugo and León).

Natural slate is extracted from both quarries and mines, being surface quarries the most common and traditional way of producing natural slate. Once the overburden is removed, slate is sawn in large flat slabs that are then carefully cut into smaller natural slate blocks, and transported to a transformation factory.

Blocks are then hand split by skilled craftsmen called “labradores” into roofing slates of the desired thickness. All slates then undergo final inspection, with each producer having its own selection and quality criteria. Spanish slates are packed vertically in wooden pallets for distribution.

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What should you know about Spanish slates?

What is Spanish slate?

Why Spanish slate?