Petrography of roofing slates

Abstract

Roofing slate is one of the world's most popular dimension rock products. This special type of slate can be split into regular and thin tiles forming an exceptional covering material. Many historical heritage buildings along Europe use slate covers. Although slate has been quarried worldwide for centuries, in the second half of the past century the production of roofing slate increased hugely, especially in Europe, where the largest outcrops known to date are located.Despite its importance as a construction material, roofing slate has not been the target of a proportional number of scientific publications, as compared to other materials such as granite, sandstone, marble or limestone. This could be due to the general perception that roofing slate is a rather simple rock with a relatively unvarying mineralogy consisting of quartz, chlorites and mica, and having a monotonous structure dominated by the slaty cleavage and various fracture planes.This paper deals with the main features of the roofing slate industry, i.e. petrological and mineralogical characterization, and their application on slate production, as well as additional phenomena and significant factors affecting quality which are rarely considered, such as weathering and durability.