Slate industry in Spain keep cutting machinery cool. After quarrying regional authorities often dictate that the landscape is returned as much as possible to its original state, and waste rock left as part of the extraction process is returned adjacent to the quarry Slate industry in Spain 90% of Europes's natural slate used for roofing originates from the slate industry in Spain, with the region of Galicia being the primary source of production. Slate is a fine-grained metamorphic rock that splits into thin, smooth-surfaced layers. Metamorphic rock is rock which was once igneous or sedimentary and has been subsequently subjected to heat and pressure
Slate the 20th century. For example, "roof slate" referred to shale above a coal seam, and "draw slate" referred to shale that fell from the mine roof as the coal was removed. Slate is mainly composed of the minerals quartz and muscovite or illite, often along with biotite, chlorite, hematite, and pyrite and, less frequently apatite, graphite, kaolinite, magnetite, tourmaline, or zircon as well as feldspar. Occasionally, as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. These spheres are sometimes deformed by a subsequent applied stress field to ovoids,