Slate
Slate is a natural resource quarried with a low impact on the environment. Typical slate quarrying production does not involve any chemical processes. In most cases only locally sourced water is used to keep the cutting machinery cool.
During excavation, unusable rock is excavated. The regional authorities have strict guidelines about how this material is treated. Often slate waste is returned adjacent to the quarry and the original landscape re-created with landscaping including reinstatement of soil, grasses and other native vegetation.
Sustainability
In terms of sustainability, slate wins over other forms of roofing. Recent independent research has concluded that when compared to concrete or clay tiles, or to copper or lead, slate’s minimal processing gives it the lowest embodied energy of all roofing materials. In addition, the same research states that its long life expectancy, low maintenance and recyclability give slate credibility in terms of environmental impact.
Domestically quarried natural slate is in short supply in the UK. In search of a suitable alternative, Spain is the best choice due to the volume of supply available and the distance to transport. Slate sourced from Spain as opposed to further destinations such as China or South America results in significantly lower CO2 emissions.
How slate is extracted
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Geological surveys locate areas of potential slate extraction
Samples are taken to allow the purity and quality of the slate to be verified. The quarry area is established and unusable material (overburden) is removed. Diamond beaded steel cutting cables are used to saw large blocks from the quarry. These blocks are transferred to the production centre to be sawn into regular smaller blocks, using their natural cleavage planes. Skilled craftsmen grade the blocks according to quality and thickness, after having split them into a pre-determined size.
After final quality control measures, slates are packed into crates, often with batch information so that future matches will be possible for longer term ongoing projects
