Slate is a naturally quarried or mined product, so the process of extracting the stone is somewhat resource intensive.
That said, the production of slate doesn’t involve the use of furnaces or harmful chemicals, unlike some other landscaping materials.
Slate chippings are also recyclable, and are often produced from roofing or flooring tiles removed from buildings. Rather than just discard the slate, the tiles are broken down into chippings and sold as high-quality landscaping aggregate.